SE sport 300 hydrofoil

[BigE]

Looking for an SE Sport 300 Hydrofoil

Anyone got one they want to part with ?


BigE

[shakey55]

I have the 400. Very happy with performance and NO DRILLING


Sent from my iPhone using Ausfish forums

[gazza2006au]

I have the Ozplate that came on my engine i took it off to fix in a test drum and found my boat doesn't even need a hydrofoil

BigE how come your fitting one?

[BigE]

Gazza
borrowed one from a mate and it a good amount of improvement ( and i didn't think the yalta's performance was poor to start with)

had a 160km run in about 15's with some chop (scarby to 12mile to wide of the cape to tanga and back to scarby) fuel burn went from 2km to litre to 2.2 km to the litre engine had a bit more useable trim at cruise and the boat just felt "higher " in the water seemed to add more lift all all planing speeds.

in short I liked it on this hull, I know they dont work on all hulls and there not some sort of black magic but 10% better fuel burn at 40kph is worthwhile improvement , thought someone might have a used one they didnt want ($$$ for Xmas)

BigE

[gazza2006au]

Big do u think the sifference could have been the conditions on the day?

[Andy56]

Gazza
borrowed one from a mate and it a good amount of improvement ( and i didn't think the yalta's performance was poor to start with)

had a 160km run in about 15's with some chop (scarby to 12mile to wide of the cape to tanga and back to scarby) fuel burn went from 2km to litre to 2.2 km to the litre engine had a bit more useable trim at cruise and the boat just felt "higher " in the water seemed to add more lift all all planing speeds.

in short I liked it on this hull, I know they dont work on all hulls and there not some sort of black magic but 10% better fuel burn at 40kph is worthwhile improvement , thought someone might have a used one they didnt want ($$$ for Xmas)

BigE

Its an interesting topic on its own. I always suspect statements where the foil seems to "fix" underlying issues. Keeping the boat on the plane will improve your consumption figures. So working backwards, why is your boat not keeping on the plane without a foil? What are the factors at play?

Weight balance of boat hull, power available, depth of motor ( is the anitventilation plate too high or too low), prop selection, is the center of balance too far back with the weight of the outboard, is the mptor trimmed in or out properly?

I am not totally dismissing the foil, but it does seem odd that a foil can overcome all the other issues without any draw backs.
It is logical to me that on a flat sea, it would work great in a straight line.
Its also logical that it can get the hull on "plane" at a lower speed. But at higher speeds, 40km/hr, it should be out of the water, so no effect. So whats going on here? If its still in the water, it would signal other issues.

However, what happens to boat behavior when its rough? To me its also logical that if your weight balance is wrong or the motor is set too low and the bow is flighty, it could become hard to handle with a foil in rough seas, you would end up traveling slower to remain on plane compared to a well sorted boat. It will feel like a rear steer car. If the logic is wrong , please correct me. I havent read anywhere a logical description about how a foil affects a boat ( apart from more lift at low speeds.) or which issues are fixed or exaggerated. Advertising hyperbole doesnt count. I can only use logic to try and understand the fundamental forces involved.

I am sure others will say it just works, get over it or stop trying to intellectualise it. Can't help the engineer in me . I need to know why before i accept something that appears to cut across logic.

I found this snipet on THT, "Of course they give lift, my point was that the hull should provide the lift rather than the engine--They work, but they address a problem that doesn't belong to the engine..."

[scottar]

Its an interesting topic on its own. I always suspect statements where the foil seems to "fix" underlying issues. Keeping the boat on the plane will improve your consumption figures. So working backwards, why is your boat not keeping on the plane without a foil? What are the factors at play?

Weight balance of boat hull, power available, depth of motor ( is the anitventilation plate too high or too low), prop selection, is the center of balance too far back with the weight of the outboard, is the mptor trimmed in or out properly?

I am not totally dismissing the foil, but it does seem odd that a foil can overcome all the other issues without any draw backs.
It is logical to me that on a flat sea, it would work great in a straight line.
Its also logical that it can get the hull on "plane" at a lower speed. But at higher speeds, 40km/hr, it should be out of the water, so no effect. So whats going on here? If its still in the water, it would signal other issues.

However, what happens to boat behavior when its rough? To me its also logical that if your weight balance is wrong or the motor is set too low and the bow is flighty, it could become hard to handle with a foil in rough seas, you would end up traveling slower to remain on plane compared to a well sorted boat. It will feel like a rear steer car. If the logic is wrong , please correct me. I havent read anywhere a logical description about how a foil affects a boat or why it fixes issues or which issues are fixed or exaggerated. Advertising hyperbole doesnt count. I can only use logic to try and understand the fundamental forces involved.

I am sure others will say it just works, get over it or stop trying to intellectualise it. Can't help the engineer in me . I need to know why before i accept something that appears to cut across logic.

I found this snipet on THT, "Of course they give life, my point was that the hull should provide the lift rather than the engine--They work, but they address a problem that doesn't belong to the engine..."



It all depends on your situation Andy. For the record - all of my boats have run foils for the last 25 years - and they were run without too.

Sure on some boats, a foil can "fix" a problem caused by an underlying issue that could have been otherwise rectified. Sometimes they do it at a fraction of the cost of a "real" fix. Do they do everything they say - yes but what they don't elaborate on is "under certain circumstances". They will pretty much make every boat plane quicker - hard to debate that and at some point in the rev range, they will save fuel (it's the "at some point in the rev range they neglect to mention) purely because due to the extra stern lift the hull is now planing and not pushing water - again - basic physics and pretty much impossible to refute.

On some boats, mine included, they get fitted simply because it allows the hull to simply do things it is physically incapable of doing without the foil - main one for me is plane at slower speeds for a smoother ride in rough conditions. This comes down to what sort of skipper you are and what you want your boat to be capable of doing. I have spent a fair bit of time offshore in some bloody horrible conditions in my younger days - going fast enough to allow the hull to generate sufficient lift when it's like this is simply not an option. A foil however is the cheapest and easiest way to make it possible. My 15'er would plane at 8 knots - not bow in the air pushing water - a clean flat plane. The results with the Victory are similar but at a higher speed. The fuel saving at minimum boat speed was significant in the Victory - it went from 0.6km/l @ 3000rpm with it's bow in the air to 1.2km/l (sometimes better) with a better ride as the hull was flat and using the bow as designed. Not fixing a "fault" - simply allowing the hull to do something it would under normal circumstances be unable to do.

My 11 foot tinnie is the same. If you can find an 11 footer that will plane at a slow speed without it's nose in the air with a 100kg plus in the rear corner - let me know. Fit a foil and set the trim - happy days.

The negative - in my personal experience - nothing that hasn't been caused by me and the way I have driven the boat. They generate a huge amount of lift - if you don't use your trim button, you can cause yourself grief for sure - heavy steering, ploughing and the subsequent broach are certainly all possibilities but if you learn to use it properly - just like any other "tool", the benefits far outweigh the negatives IMO. Small tinnies especially, do require some thought - I regularly adjust my trim pin depending on load and sea conditions - something I will bet that not a lot of the people who have experienced hairy moments have done. On a rig with power T&T it is obviously a lot easier.

Brands - I've run a few. Stingrays in the early days - even have a mate that ripped a mould and cast me one from alloy at one stage. I tried the SE Sport on the Victory but it created a huge amount of drag. I ended up with a Permatrim which still created some drag but a heap less. Took it off for a grand total of one trip when I fitted trim tabs - it went straight back on.

[blacklab]

That is well said Scottar.
Perhaps some do use them to correct bad set ups, or rigs they have bought under powered or set up badly,
Think of it as an aid, an improvement aid, look how trim tabs can be used, nothing wrong with the boats set up when wind and tide or weight distribution needs a tweek on trim tabs, Just adapting to the situation.
Scottar, a friend of mine a while back fitted one of those Tailfin hydrofoils, haven't had the opportunity to go out with him to feel the difference yet, but he claims it has completely transformed the performance of his boat, which I didn't think he had an issue in the first place. Cost him a couple of hundy and the way he's talking, he stated it's like a new boat, hole shot, steering, leveling up of the boat over the rough chop etc etc, I don't know whether or not you've seen one, but Geeez, there dead set UGLY ! I dont know whether I would subject an out board I own to bolting something that visually unappealing, BUT, My mate is raving about it. they have a facebook page etc, after looking at there sire, my opinion hasn't change, there still damn ugly.
An interesting read But........

[scottar]

That is well said Scottar.
Perhaps some do use them to correct bad set ups, or rigs they have bought under powered or set up badly,
Think of it as an aid, an improvement aid, look how trim tabs can be used, nothing wrong with the boats set up when wind and tide or weight distribution needs a tweek on trim tabs, Just adapting to the situation.
Scottar, a friend of mine a while back fitted one of those Tailfin hydrofoils, haven't had the opportunity to go out with him to feel the difference yet, but he claims it has completely transformed the performance of his boat, which I didn't think he had an issue in the first place. Cost him a couple of hundy and the way he's talking, he stated it's like a new boat, hole shot, steering, leveling up of the boat over the rough chop etc etc, I don't know whether or not you've seen one, but Geeez, there dead set UGLY ! I dont know whether I would subject an out board I own to bolting something that visually unappealing, BUT, My mate is raving about it. they have a facebook page etc, after looking at there sire, my opinion hasn't change, there still damn ugly.
An interesting read But........

Agree blacklab - ugly as a hatful of aholes. Best trialled on someone else's motor. Perhaps if old mates website didn't read like a dodgy copy of a Danoz Direct add

[Lovey80]

For me it fixed a problem that I created myself. After I got rid of the 25l tote tank in the little Webster and replaced it with a 65l built in tank in the ass of the boat it made it really ass heavy. The boat simply wouldn’t plane or ride like it did before and I was struggling to get any top end performance. After the foil however it was chalk and cheese. It launches onto the plane and I actually now have some prop testing to do because the current one spins out far too easily.

The one downside though is I have lost some trim up in the bow when it gets snotty. The boat wants to sit level in all trim settings. Being a creek boat that doesn’t happen very often.

[Paul071978]

I’ve had some average experiences with these things especially with beam and following seas. And yes I do know how to trim correctly. It made the boat very unpredictable. I wasn’t happy at all and removed it promptly and placed into the recycle bin

[scottar]

Just to elaborate a bit further on a couple of points you raised - yes, ideally over 40kph the foil will be out of the water - hull dependant. All hulls will have a minimum speed at which they generate sufficient lift to get their weight out of the water and planing. This speed will vary though based on weight given similar hull design. On a light alloy rig, it will obviously be less than on a heavy lay up glass rig . Weight distribution will play a part too but it doesn't matter how you distribute weight if your hull weighs substantially more - you will need more speed - unless you can somehow generate more lift.

"Travelling slower to remain on plane". Not at all - unless you want to. The trim control will control just how much lift the stern is generating on a good installation. If you want more boat speed, trim it up and give it the beans. Of course if it has gotten to the point that you want to slow down, remain in control instead of hanging on for dear life, not to mention avoid bashing the shit out of your boat and yourself, then the rig with the foil has got it all over the one without. I've pulled the foils off at various times for whatever reason - they have never been off long.


"I found this snipet on THT, "Of course they give lift, my point was that the hull should provide the lift rather than the engine--They work, but they address a problem that doesn't belong to the engine..." - One way of looking at it. The other is that the amount of lift generated by a hull is fixed to a point (short of fitting trim tabs) - it has a minimum hull speed below which it just won't work efficiently. Sea conditions are certainly not. Most hull designs are a compromise for a comfortable balance of stability, performance and seakeeping. They aren't designed to go fast in rough conditions despite what the manufacturers and fanboys tell you. The foil is, short of latitudinal correction, a "poor mans" version of trim tabs when installed correctly courtesy of the trim button which creates the variable lift the hull can not. Sure, if you are a diehard or a masochist that doesn't mind a kicking, no foil required but for me at least, that simply isn't the case.

[scottar]

I’ve had some average experiences with these things especially with beam and following seas. And yes I do know how to trim correctly. It made the boat very unpredictable. I wasn’t happy at all and removed it promptly and placed into the recycle bin

Like any bolt on bits - there are always going to be some combinations that simply do not work. What hull, engine, foil package was it Paul?

[TREVELLY]

I have a deep V 6m boat with 175 Suzuki and the boat is a lot more stable (it rolls more side to side without foil - acts like a sway-bar) with hydrofoil and has better hole-shot and cavitates less.

I tried without and got same maximum speed but the performance was definitely inferior without the foil.

So nup - you can't have mine.

$140 from https://www.whitworths.com.au/sport-marine-technologies-se-sport-300-hydrofoil-black

[NAGG]

Foils clearly have their place & just sometimes a motor / hull combinations needs some help . My very first boat a 5.35 Quintrex CC with a 75 Mariner would porpoise badly on flat water when running at speed ……. because the boat was light & the pivot point was basically under the driver . There wasn't much you could do - trim all you like you still couldn't stop the bounce . It was suggested that I go with some alloy dolphins & problem solved.
My seajay barramasta was originally fitted with a 70 Yammi ….. never had an issue ( just underpowered when loaded up) - I then upgraded to a 100 yammi & all the sudden there was an issue - we raised the motor 1 notch - not fixed . It was only associated with being trimmed out running at 4500 revs+ on flat water …… went with a an SE400 - problem solved . Sometimes you cant distribute weight ideally or have people stand on their head with one leg out to the side ;).

Chris

[Paul071978]

It was on a 17ft mustang cc and 115hp

[blacklab]

SO, Would it be a consensus that Trim tabs would give a better end result with more options available than when fitted than a foil,
But, sometimes a foil is enough to get satisfactory results.......
???????

Col

[Paul071978]

Trim tabs are by far the better option and worth the few extra dollars. Especially for resale too. I wouldn’t touch a boat with a foil as it means poor hull engine combination or design

[blacklab]

Trim tabs are by far the better option and worth the few extra dollars. Especially for resale too. I wouldn’t touch a boat with a foil as it means poor hull engine combination or design

I agree with you that trim tabs are the ultimate,
But, wasn't the theory of foils being for poor hull design or engine combination just squashed in previous posts ?
I can't agree with your assumption there sorry.
I wont put a foil on mine, I'll put trim tabs on with my current rebuild and new motor,
BUT, surely with your theory, if you add trim tabs, your compensating for bad hull design or motor combination as well ?
My last boat, was a popular major brand, motor was in range of manufacturers specifications, I put trim tabs on to balance, plane earlier and to keep the boat more level going thru that horrible wave set rather than dropping off the plain, Isnt that what those that use a foil are trying to achieve in a less costly way ???

Col

[bluefin59]

A lot of nay sayers about foils but I have had them and always found the boat handled better as far as nose attitude that I was after . I have heard people say they are dangerous and that boats aren’t setup properly but it all depends on weight distribution and the way the boat handles and some of us have been happy with them . SE Sport was on my bluefin for 14 years and it handled great in my books so it’s very individual but it can be a cheap fix for bad habits . Matt

[NAGG]

Hey sometimes you cant fit trim tabs to a boat .
My Seajay couldn't take trim tabs if you ran a transducer off the transom .

you need to remember that foils are there primarily for lift ....... on marginally powered boats or carrying a lot of ass end weight & to be honest would often do that better than trim tabs

Chris

[Paul071978]

Trim tabs are fitted to most boats 20ft plus to assist planning if and when required. Once the boat is on a plane then the tabs can be lifted to level with the hull effectively extending the waterline length. However foils act in a different manner. Increases risk of broaching in large following seas due to increased surface area of cav plate. Haven’t seen foils fitted to a stern drive leg before.

These are my experiences and I know many others can concur but hey some people obviously swear by them

[scottar]

SO, Would it be a consensus that Trim tabs would give a better end result with more options available than when fitted than a foil,
But, sometimes a foil is enough to get satisfactory results.......
???????

Col

I would call that a fair statement.

[blacklab]

It seems your experiences with a foil are the opposite to the views of those that actually have them on there boats here on this forum.
Perhaps all those "others" you refer too could join up here and give us a more balanced view.

"foils act in a different manner increasing risk of broaching"
Is that a personal view or can you back that up some how,
My old boat had a foil on for 7-8 years and was one of the most shore footed boats in a following sea I have ever owned.
incorrect use of trim tabs, in a following sea, will see your boat become a submarine !
I guess, a foil, when the boat is incorrectly driven in a following sea could do the same, couldn't comment, that's never happened to me.
If I end up not having room for trim tabs once I fit everything up, I wouldn't hesitate in fitting a foil.

Col

[Triple]

I have tabs and a permatrim... only really use the tabs to correct list. Have tried with and without the permatrim in various conditions and it stays on now.

[scottar]

Trim tabs are fitted to most boats 20ft plus to assist planning if and when required. Once the boat is on a plane then the tabs can be lifted to level with the hull effectively extending the waterline length. However foils act in a different manner. Increases risk of broaching in large following seas due to increased surface area of cav plate. Haven’t seen foils fitted to a stern drive leg before.

These are my experiences and I know many others can concur but hey some people obviously swear by them

There is enough bad press to say that some set ups certainly don't suit and everyone's experience will be different. Trim tabs get fitted most of the time for lateral trimming - compensation for larger cabin style planing hulls tendency to lean into the wind and to allow for variation in loading as well as providing stern lift as required.

Like any accessory for a motor - right down to props, not every one suits a particular installation. On a previous boat I ran different foils at different times due to variations in design causing changes in loading conditions. The hull started life as an open tinnie. I fitted a full size Stingray initially which for 99% of what was required (bar crossing and bluewater fishing) was brilliant. It did produce enough lift at WOT to bury the nose but easily fixed with trim. Three years into ownership I grew tired of hanging onto a tiller for hours on end and converted it into a centre console - adding the console and a 60 litre fuel tank and a new engine of the same horsepower. With the extra weight forward and the shift in driving position, I found the full size foil to be generating too much lift and went back to a Stingray Junior. It fixed the lift issue and while it meant a slightly higher planing speed, it was still acceptable. Further down the track I added an auxillary engine, second battery, electric motor, casting platform, bait tank etc etc - and needed more lift again - back to the full size foil and all was well.

I also had to try a couple of different ones on the Victory before being happy. Point being, when most people bolt one on and have an "Oh shit" moment, it could simply be the one chosen isn't the right one for them. I dare say most would then simply remove the offending item without trying to figure out the why's and how's. Would trying some others produce a different outcome - who knows but there is enough good press out there from very happy users that they can't simply be written off as a bad thing.

They do get fitted to stern drives - if you check the boats in the storage racks at marinas you see a few.

[Paul071978]

If foils are such a fantastic idea engine manufacturers would be redesigning cav plates.

A simple search on other boating and fishing forums Oz or US based on foil related issues will confirm I’m not the only person who has experienced issues.

Like I said some people say they’re great. I’m just sharing my personal experience. Do whatever blows your hair back

[BigE]

Gazza
borrowed one from a mate and it a good amount of improvement ( and i didn't think the yalta's performance was poor to start with)

had a 160km run in about 15's with some chop (scarby to 12mile to wide of the cape to tanga and back to scarby) fuel burn went from 2km to litre to 2.2 km to the litre engine had a bit more useable trim at cruise and the boat just felt "higher " in the water seemed to add more lift all all planing speeds.

in short I liked it on this hull, I know they dont work on all hulls and there not some sort of black magic but 10% better fuel burn at 40kph is worthwhile improvement , thought someone might have a used one they didnt want ($$$ for Xmas)

BigE

Wow this thread took off in an unintended direction!!
Just for some clarity around my experience
Boat is a Yalta 2200 with a 200hp and has trim tabs
Previous performance prior to running the foil was very good , boat runs hard and from my experience a 6 meter plus running at 2KM per Ltr is actually not to shabby.
The boat wasn't displaying any bad traits I just tried the foil cause it was there ( and beers)

Cant deny the improvement in fuel and you will notice i took a fair run covering all compass direction to get a good feel for it at different directions

I always take improved fuel usage as pretty good indicator of engine load and less is always better.

I agree and i am surprised at the improvement at 40kph where the boat is well and truly on the plane ( low planing speed is 25KPH)

dont know the where's why's of the outcome .... but i like it.

Back on course now ....... does anyone have one they don't want??


BigE

[scottar]

Might have to talk to Santa;)

[blacklab]

If foils are such a fantastic idea engine manufacturers would be redesigning cav plates.

A simple search on other boating and fishing forums Oz or US based on foil related issues will confirm I’m not the only person who has experienced issues.

Like I said some people say they’re great. I’m just sharing my personal experience. Do whatever blows your hair back

Guess most of our hair blows south, by the looks of those that like foils here......
I don't search other boating forums, for opinions, there's enough blokes here with years of experience,
And i usually make my own mind up in the end, based on practical experiences.
choice is an amazing thing.......

Col

[Dignity]

Seems everyone has a different point of view and are totally entitled to them. On my quinine WB Dory 4.2 I tried lifting the motor changing trim pin, moving weight and in the end put a foil on, like chalk and cheese but it can get flighty if its just me on board. With the Allison I put trim tabs on, main reason for faster boats these days is lateral trim, boats become big aerofoils with any wind blowing from the side and you will get a low pressure side hence the lean, and trim tabs to correct the issue. Other times in different seas used to adust the bow, as mentioned by others. I've never seen it mentioned they are for planing reasons, it just doesn't make sense (not being an engineer).

Outboard manufacturers are aware that if they produced motors with larger anticav plates it would certanly improve most motors but 2 things stop them.
No1 cost, if they don't have to do it they won't, and
No2 (the biggie) there are so many variables with boats that is is easier to point the finger elsewhere as being the issue as this also adresses point No1.
Both of these points were discussed over some very nice Saki with an engineer who had been involved in outboard designs for a major brand.

I've contemplated a hydrifoil/permatrim for the Allison but still playing with motor height, props, weight distribution although this is limited with the storage configuration. Once I get as far as I can with those I'll reconsider this issue.

Big E, looks like you might have to just buy one from a retailer.

[stevej]

trim tabs would be a better option in most cases, except for under powered hulls which will always be dogs in the handling department
the negatives are too great for me to fit them

[NAGG]

If foils are such a fantastic idea engine manufacturers would be redesigning cav plates.

A simple search on other boating and fishing forums Oz or US based on foil related issues will confirm I’m not the only person who has experienced issues.

Like I said some people say they’re great. I’m just sharing my personal experience. Do whatever blows your hair back

One size doesn't fit all though , does it ?

Take for instance my seajay barramasta ....... compare the same boat as originally purchased with a 70hp yammi 4 stroke with a single cranking battery. Vs the addition of 2 x 120amp batteries + a minn kota at the pointy end .... + heavy anchor ....... the boat had a nose down attitude. Put a 100hp on the back & add a house battery & the boat porpoised . How do you design motors for such a broad spectrum of hull /boat configurations ?

Chris

[Moonlighter]

I have had foils on previous boats. SE sport.

On my 4.8 JBS I first had a 70 Yammy 2 stroke, and it porpoised bad when trimmed out past half way. It actually had a ballast tank fitted up forward from new by the boat builder to try to fix the issue.

These were in the days before I understood very much about things like engine height and its effect on boat attitude, trim and porpoising. I stuck a SE spot on there and it was better, but still not perfect.

A couple years later my steering cable froze up and I decided to fit hydraulic. At the same time, a friend suggested we check engine height and as a a result we lifted the engine 1 hole higher and replaced the alloy prop with a better stainless prop - bingo - problem solved! Could trim well out and no porpoising.

I took the foil off to see what happened, and it now made no difference. So it stayed off. I even took the ballast tank out from the bow and nothing changed!

Subsequently a couple years later I fitted a Tohatsu TLDI90 to the boat, significantly heavier. It was fitted at the correct height, and I found I could trim way out with the stainless Vengeance prop I fitted with no porpoising. So here we have added 30kg extra weight at the transom, taken 20kg of ballast out of the bow, but not elicited problems.

What I am getting at is that my main concern with foils is is the propensity for people to jump straight to foils as a solution, without first figuring out what the problem really is and why its happening.

A foil may well be a solution or part of a solution, but like everything, unless you have taken the time to REALLY understand what the problem is then you might just be treating a symptom and not the underlying problem. And maybe creating a new problem in the process.

If you have got engine height optimised, and weight distributed as sensibly as it can be, and the boat is propped correctly - with a prop that is well suited to the main useage of the boat - then a foil would be definitely worth considering.

But if you havent got those things all sorted, adding a foil is just a crap shoot.

[Andy56]

I have had foils on previous boats. SE sport.

On my 4.8 JBS I first had a 70 Yammy 2 stroke, and it porpoised bad when trimmed out past half way. It actually had a ballast tank fitted up forward from new by the boat builder to try to fix the issue.

These were in the days before I understood very much about things like engine height and its effect on boat attitude, trim and porpoising. I stuck a SE spot on there and it was better, but still not perfect.

A couple years later my steering cable froze up and I decided to fit hydraulic. At the same time, a friend suggested we check engine height and as a a result we lifted the engine 1 hole higher and replaced the alloy prop with a better stainless prop - bingo - problem solved! Could trim well out and no porpoising.

I took the foil off to see what happened, and it now made no difference. So it stayed off. I even took the ballast tank out from the bow and nothing changed!

Subsequently a couple years later I fitted a Tohatsu TLDI90 to the boat, significantly heavier. It was fitted at the correct height, and I found I could trim way out with the stainless Vengeance prop I fitted with no porpoising. So here we have added 30kg extra weight at the transom, taken 20kg of ballast out of the bow, but not elicited problems.

What I am getting at is that my main concern with foils is is the propensity for people to jump straight to foils as a solution, without first figuring out what the problem really is and why its happening.

A foil may well be a solution or part of a solution, but like everything, unless you have taken the time to REALLY understand what the problem is then you might just be treating a symptom and not the underlying problem. And maybe creating a new problem in the process.

If you have got engine height optimised, and weight distributed as sensibly as it can be, and the boat is propped correctly - with a prop that is well suited to the main useage of the boat - then a foil would be definitely worth considering.

But if you havent got those things all sorted, adding a foil is just a crap shoot.

thats where i am at the moment. Got the height right, getting the weight right and then we shall see what prop i need. Its been a good discussion so far. I have learned a thing or two as well. Different foils at different sizes have different amounts of lift. Sounds obvious now.

But i still pose the question. What keeps the hull from planing without a foil? Thats my starting point. I know mine has had two of the three majors out. Engine height and now weight distribution. My preference is 1/ Get the basics right 2/ not to use one or 3/ fine tune as a last resort.
If all you ever did was calm water fishing and a constant weight distribution, it just wouldnt be an issue, fit it up asap if you feel the boats not right. For the rest of us, you would have to delve deeper. For me , knowing the motor was buried would be a constant nagg even if a foil "fixed " an issue.

[scottar]

Insufficient boat speed. Problem is that by the time you have sufficient boat speed for a lot of boats, in rough weather your ride is starting to suffer. Not "poor design etc" - just the way it is. The laws of physics. Same reason a light small plane gets off the ground at a heap less air speed than a jet liner but is then also affected a lot more by turbulent air. Think about what they do with a jet when they want to slow down - take off and landing.

[ozscott]

As Scotar says its horses for courses. I had an SE Sports 300 on my Vagabond and it was a pig. Took it off and it was good. Put on Bennet hydraulic tabs and it was brilliant. Put the SE back on with tabs and it was a pig. Pulled it straight back off.

Have had a Stingray on a V163 Haines. Excellent. Have a Lazilas 2 piece foil on my m40d2 Tohatsu on 4.5 BlueFin tinny and its excellent - better stability, quicker planing, lower planing speed, better steering. Took it off when I got my new Solas prop. Put it back on. Definitely better on. Handful of other boats that foils helped on.

Cheers

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[shakey55]

Looking for an SE Sport 300 Hydrofoil

Anyone got one they want to part with ?


BigE

I see they are for sale in shops for about $150

Found this for you if you are interested. The rest is up to you

https://www.gumtree.com.au/s-ad/warana/boat-accessories-parts/outboard-hydro-foil-se-sport-300/1203866210


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[Dignity]

I see they are for sale in shops for about $150

Found this for you if you are interested. The rest is up to you

https://www.gumtree.com.au/s-ad/warana/boat-accessories-parts/outboard-hydro-foil-se-sport-300/1203866210


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You can now get them in white and grey to suit your motors if you shop around

[NAGG]

SE400 is the way to go ...... no drilling . If it works for you - awesome! …. if it doesn't - unbolt it & flog it off & not a hole to be seen

Chris

[Andy56]

Insufficient boat speed. Problem is that by the time you have sufficient boat speed for a lot of boats, in rough weather your ride is starting to suffer. Not "poor design etc" - just the way it is. The laws of physics. Same reason a light small plane gets off the ground at a heap less air speed than a jet liner but is then also affected a lot more by turbulent air. Think about what they do with a jet when they want to slow down - take off and landing.
I understand what your saying, but my experience with my signature suggests other factors. it just got on the plane without any bow gymnastics. Going to a 4 blade prop made it an even better transition. Granted my 420 is in another league, but i know how it should be. Time will tell if i get it that way. If i exhaust all options and its still iffy, i wont hesitate to go the foil.
I am happy so many people have good experiences with a foil, but i am of the type of person who always asks whyTF? And really, it just hasnt been explored enough on any forum. Lets get more info and experiences so we can bed this issue once and for all.

[ozscott]

Andy what do you mean? What hasn't been explored?

Cheers

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[Andy56]

to me its quite obvious what hasnt been stated in all the feel good stories. like what other strategies to getting the boat dynamics right have been employed? Some one says he gets better fuel economy at 40km/hr with a foil, that just flys in the face of logic. Does that mean the motor was too far under to start with? Or oopps sorry forgot to mention the 150kgs i added, lol. ( thats an exaggerated joke )
It would be good to know of experiences where the owner has got everything else right first and then added a foil compared to just adding a foil and alls hunky dory. Its the missing info thats of more relevance. A more scientific approach compared to " it just works" for me. Its not to belittle people's experiences, but more an understanding of what forces are really at play.
I hope thats clearer ozscott.

[ozscott]

Ok good mate. Glad to know its clear to you. Good luck with getting into the science behind all the 'feel good' stories.

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[Andy56]

if you dont ask the right questions, you dont always get the right answers .;D

[scottar]

From a personal perspective with the Victory & 200Ho E-Tec Andy, the first time I ran it offshore in heavy weather, prior to any modifications, the ride was bow up and the fuel consumption was hideous - a litre of fuel every 600 metres. I had had access to a company owned Victory with a carby 150 V6 OMC motor (with a Stingray) that didn't drink like that. In any conditions apart from heavy weather however, it was a far superior version of what I was familiar with - higher top end, less fuel. The experimentation started - props first off - went to a 4 blade in a couple of different sizes and patterns and as a consequence was able to also lift the engine as high as it will go (tried every hole from where it was when I got it to the highest as well). Fuel economy improved at mid range rpm but only if sufficient boat speed was applied to make the hull climb out of the hole properly which then produced a ride in heavy weather I wasn't entirely happy with. Below this speed with the bow in the air, as is the case with all planing hulls, the engine is using a heap of fuel. Going from previous experience with foils, I grabbed what the local retailer had on the shelf - SE Sport 300 - fixed the ride but created enough drag that it took near on 500RPM off my WOT even with the engine at maximum height. Flogged it off and ordered the Permatrim - problem solved. Later when finances permitted, I ordered a set of 12x9 trim tabs - and took the foil off as I figured they would do the same job - which they did to a point but with the foil back on as well the difference was enough that keeping it on was the best option - at 3000 rpm fuel use was down to 1km/litre. Another prop change allowed me to get it to 1.2km/litre at 3000 rpm. There were small improvements with pretty much everything I tried but adding the foil and tabs was the biggest change with the foil being the best "value for money" by a pretty significant margin.

Having done the exercise first hand, Big E's results don't fly in the face of logic for myself as my results are similar but more pronounced due to hull dynamics. Essentially what is happening is the little bit extra lift at that speed is putting his hull into an attitude that makes it work more efficiently. Will it happen for every hull - yes at some point in the RPM range but whether that point is at a usable part of the rev range will depend on the hull and how it is used. Could there be issue created at other RPM's - certainly but you won't know until you try. They aren't a silver bullet for every boat but if you know what it is you are trying to achieve they are a viable tool.

I also don't view my process as trying to fix a problem so much as simply trying to make my rig do something outside it's design brief. Different hulls are designed to achieve different outcomes - some designers are go fast fiends, some are looking to make the most efficient hull possible, some are looking for stability or ride or a variation somewhere in between - every boat is different - even before adding a variety of other factors. I knew what I wanted - stern lift but I wanted it at a certain boat speed - not RPM. By changing to a "stern lifting" prop I got lift at RPM - because the prop didn't have as much slip and the boat was going faster and thus the hull getting into it's design speed - not what I was wanting to achieve. I needed lift without speed. I could have fitted a lighter motor - $25K, trim tabs $1.5K or the foil - $290.

[BigE]

to me its quite obvious what hasnt been stated in all the feel good stories. like what other strategies to getting the boat dynamics right have been employed? Some one says he gets better fuel economy at 40km/hr with a foil, that just flys in the face of logic. Does that mean the motor was too far under to start with? Or oopps sorry forgot to mention the 150kgs i added, lol. ( thats an exaggerated joke )
It would be good to know of experiences where the owner has got everything else right first and then added a foil compared to just adding a foil and alls hunky dory. Its the missing info thats of more relevance. A more scientific approach compared to " it just works" for me. Its not to belittle people's experiences, but more an understanding of what forces are really at play.
I hope thats clearer ozscott.


Ask away Andy i'll do my best to answer , i am by no means an expert but this is not my first boat any I am smart enough to try and look at an apples and apples type comparison...... (lets face it i'm looking to buy one not sell one so someone who has one that does work for them would be a bonus for me)
comparison was with the boat in it's usual trim and load and yes i have moved the load on many occasions to see what works and what doesn't , i am lucky enough to have two 160ltr eskies which i can set up under the seats (forward) to right down against the transom (back) i have tried the height both up and down and have come back to where the dealer had it fitted, have tried 2 three blade props and a 4 blade prop ( I'm a fan of 4 blades but the 3 blader gives better performance on this engine on this boat)

BigE

[Paul071978]

Good point one size foil wouldn’t suit all applications. However from my knowledge outboard manufacturers don’t offer foils as an optional accessory nor have I ever read a boat engine test article mentioning the use of foils??Especially considering outboard manufacturers are really pushing fuel efficiency.

Happy to be corrected. Just food for thought

[scottar]

Good point one size foil wouldn’t suit all applications. However from my knowledge outboard manufacturers don’t offer foils as an optional accessory nor have I ever read a boat engine test article mentioning the use of foils??Especially considering outboard manufacturers are really pushing fuel efficiency.

Happy to be corrected. Just food for thought

Can't say I have ever seen one either Paul but that doesn't mean that they won't have benefits for some. Like so many things we accessorize our cars and boats with, some work, some work in particular applications but not others and some don't work at all. Could be a heap of different reasons the manufacturers don't bother - not everyone wants one or needs one, plenty of aftermarket options, being conservative - not wanting to stray outside the "norm" for fear of losing market share - who knows. Ultimately with any of these devices, it really comes down to suck it and see - sometimes you win, sometimes you lose. We can only relate to our personal experiences and everyone will have different opinions.

[shakey55]

SE400 is the way to go ...... no drilling . If it works for you - awesome! …. if it doesn't - unbolt it & flog it off & not a hole to be seen

Chris

That’s the attitude I had when researching. Bought the 400 bolted on and like what it did for me so left it on.

I’ve not had a problem in a following sea, but that’s me and others may be different


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[NAGG]

That’s the attitude I had when researching. Bought the 400 bolted on and like what it did for me so left it on.

I’ve not had a problem in a following sea, but that’s me and others may be different


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That's exactly what I did with the Seajay Barramasta after I went from the 70 to 100hp ……. did the motor height thing first but the boat continued to porpoise above 4500rpm on flat water - added the SE400 & bingo problem solved - runs flat & fast . There certainly was an improvement in hole shot & the boat actually runs very well in a following sea.
I have certainly lost top end speed but that is in combination with a 4 blade stainless prop ……. no change in fuel consumption .

It just worked because f the boat set up when I added the extra weight of the bigger motor plus the addition of a house battery at the transom .

Chris

[NAGG]

It's been an interesting thread & it's excellent to hear members stories .
I did find however something amusing from the advocates of trim tabs ……… are these not added to a boat to correct an inherent issue of the hull design :-? or for those supporters is it a way of improving the "balance" of a boat ?

Let's not kid ourselves - adding a foil is no different to adding trim tabs. but usually to improve rear lift & hole shot - as opposed to lean which is the primary use for trim tabs.

My Barcrusher 615WR would be the most balanced boat I have ever owned ( set up) Driver close to centreline , Fuel tank centred & longitudinal , Icebox set over the tank - duel batteries at the transom (centred) & approx. the equivalent weight forward in the bow ( leccy motor & light weight lithium batteries . The variable is a livewell full of water . …… However with barcrusher boats "trim tabs" are virtually a mandatory accessory ……. but they are an accessory. My boat would be a bitch to drive without the trim tabs .

Anyhow I just thought it was worth pointing out .

Chris

[Dignity]

to me its quite obvious what hasnt been stated in all the feel good stories. like what other strategies to getting the boat dynamics right have been employed? Some one says he gets better fuel economy at 40km/hr with a foil, that just flys in the face of logic. Does that mean the motor was too far under to start with? Or oopps sorry forgot to mention the 150kgs i added, lol. ( thats an exaggerated joke )
It would be good to know of experiences where the owner has got everything else right first and then added a foil compared to just adding a foil and alls hunky dory. Its the missing info thats of more relevance. A more scientific approach compared to " it just works" for me. Its not to belittle people's experiences, but more an understanding of what forces are really at play.
I hope thats clearer ozscott.

Went through all of that with the tinnie, when I bought it it was set at the lowest hole, trimmed right in and was like a dog to operate which is why I guess the guy sold it. I played with trim, moving weight, height and found I still needed more so actually increased transom height so I could raise it, (also feels safer offshore but that's another matter), tried a few different props and in the end it boiled down to most probably needing another 10 horses to do the job properly. In the end put a foil on to try and immediate improvement at up to half throttle. Your argument is valid to a point, I could spend maybe $5k and increase horse power to fix the issue correctly or $125 to achieve it after exhausting all other options. That is probably the biggest reason to correct an issue properly - cost

Big E, you'd be better off starting a new thread like "SE Sport 300 Hydrofoil wanted" instead of hijacking this thread 😂😂😂😂

[Fed]

Maybe transom wedges would be a better way to go?

[Andy56]

Went through all of that with the tinnie, when I bought it it was set at the lowest hole, trimmed right in and was like a dog to operate which is why I guess the guy sold it. I played with trim, moving weight, height and found I still needed more so actually increased transom height so I could raise it, (also feels safer offshore but that's another matter), tried a few different props and in the end it boiled down to most probably needing another 10 horses to do the job properly. In the end put a foil on to try and immediate improvement at up to half throttle. Your argument is valid to a point, I could spend maybe $5k and increase horse power to fix the issue correctly or $125 to achieve it after exhausting all other options. That is probably the biggest reason to correct an issue properly - cost

Big E, you'd be better off starting a new thread like "SE Sport 300 Hydrofoil wanted" instead of hijacking this thread 😂😂😂😂

good stuff guys, its definitley filling the info gaps.

One point not mentioned so far, which really just occured to me, is using a 4 blade prop with a foil. You get the extra lift with the foil so you can probably raise the motor more. and vise versa, 3 blade probably a bit lower so it doesnt pierce the surface.

we are all trying to get the best from our rigs and i figure the more you know, the better the decisions we make. I also agree that $125 is good value, lol

[Paul071978]

I must admit a lower planning speed and increased fuel economy would be nice. With all this talk of the benefits I might try one on my current boat. Im sure I’m still recovering from the oh shit moment I experienced previously. All I can think is if I get caught when the weather turns nasty and my boat is surfing down a large swell is would i want the foil on or off? It’s not like you get a second chance 30nm offshore

[Dignity]

Andy56 tried 4 blade on the Allison, great hole shot but best I could get at WOT was 4700rpm and that was in ideal conditions.

Fed, what do transom wedges do, sounds like more trim but don't know,

[scottar]

Maybe transom wedges would be a better way to go?

Possibly Fed but then you open up a whole new can of variables when it comes to trying to strive for maximum economy. It can be very interesting to see the variation in fuel burn when I generate lift using tabs alone, tabs and foil or foil alone. While transom wedges are obviously going to do the same job as to the attitude of the vessel, it would be an interesting exercise to explore the economy outcome when using the various devices.

[scottar]

I must admit a lower planning speed and increased fuel economy would be nice. With all this talk of the benefits I might try one on my current boat. Im sure I’m still recovering from the oh shit moment I experienced previously. All I can think is if I get caught when the weather turns nasty and my boat is surfing down a large swell is would i want the foil on or off? It’s not like you get a second chance 30nm offshore

Given your previous experience it's totally understandable you would be a bit gun shy. Another thing to take into account is foil design. Some designs are "foils" - they literally create lift much the same way as an aircraft wing. Others, like the Permatrim are an extension of the AV / cavitation plate - realistically nothing more than a flat piece of aluminium with a lip down either side to stop it bending. The lips possibly do create some directional stability but when it comes to lift generation, it is entirely dependant on the trim angle of the outboard. At the end of the day, all you can do is either give one a rip or try and find someone with the same rig as yours that has one fitted - even the though they may not boat in the same conditions or drive the same way .

[scottar]

good stuff guys, its definitley filling the info gaps.

One point not mentioned so far, which really just occured to me, is using a 4 blade prop with a foil. You get the extra lift with the foil so you can probably raise the motor more. and vise versa, 3 blade probably a bit lower so it doesnt pierce the surface.

we are all trying to get the best from our rigs and i figure the more you know, the better the decisions we make. I also agree that $125 is good value, lol

Tried a few. In my case they really made such minor differences that I was totally underwhelmed for what it cost. I settled on a BRP Rebel which is a large blade area 3 blade - best mid range economy by a substantial margin and doesn't mind being run high - slowest WOT but I figure just shy of 80 clicks is quick enough anyway. It's pretty rare you get to use it anyway.

[Andy56]

Given your previous experience it's totally understandable you would be a bit gun shy. Another thing to take into account is foil design. Some designs are "foils" - they literally create lift much the same way as an aircraft wing. Others, like the Permatrim are an extension of the AV / cavitation plate - realistically nothing more than a flat piece of aluminium with a lip down either side to stop it bending. The lips possibly do create some directional stability but when it comes to lift generation, it is entirely dependant on the trim angle of the outboard. At the end of the day, all you can do is either give one a rip or try and find someone with the same rig as yours that has one fitted - even the though they may not boat in the same conditions or drive the same way .

The cavitation plate is a foil. It generates lift. How else could you trim a motor up or down and effectively alter the boats attitude.
the permatrim foils would give better lift. From basic aviation improvements. Have you noticed newer planes have a vertical fold at the end of the wings. I read that they remove parasitic eddie currents at the end of the wing and generate more lift. Boeing also claim up to 4% fuel improvement. Increasing wing span also induces more lift but the eddie currents on the wing tips also can increase drag.
so have permatrim been through a proper mathematical calculation or was it just a , nah, that looks about right? Lol. The Se400 looks like a larger wing area but those rubber boots over the bolts would create some drag, i would think.

I think if somebody wants to invent a better mouse trap, there is an opening.
Another variable is size/weight of boat. Would you use a larger wing area for a larger boat? If the motor is a weakling, would you use a smaller wing? Could these variables cause people to have different results?
have i opened a can of worms? Hahaha

[Dignity]

The cavitation plate is a foil. It generates lift. How else could you trim a motor up or down and effectively alter the boats attitude.
the permatrim foils would give better lift. From basic aviation improvements. Have you noticed newer planes have a vertical fold at the end of the wings. I read that they remove parasitic eddie currents at the end of the wing and generate more lift. Boeing also claim up to 4% fuel improvement. Increasing wing span also induces more lift but the eddie currents on the wing tips also can increase drag.
so have permatrim been through a proper mathematical calculation or was it just a , nah, that looks about right? Lol. The Se400 looks like a larger wing area but those rubber boots over the bolts would create some drag, i would think.

I think if somebody wants to invent a better mouse trap, there is an opening.
Another variable is size/weight of boat. Would you use a larger wing area for a larger boat? If the motor is a weakling, would you use a smaller wing? Could these variables cause people to have different results?
have i opened a can of worms? Hahaha

You probably have, is it a cavitation plate or an anti cavitation plate, could be a whole new argument forthcoming 😈😈

Big E, how's the hunt for your foil going.

[Andy56]

Its a foil. The antiventilation action is a direct effect.
to answer another question thats been posed, yes manufactures do vary the size of the cav plate. Yamaha V max range have a larger plate. They use it to maintain water flow over the prop.
Its the difference between average design and brilliance that we plebs have to overcome.

i think i am starting to come around. Getting on the plane earlier does have an appeal for obvious reasons. ( well obvious now).

[BigE]

Dig
no offers yet may just have to stump up for a new one.

Heading north (Bowen) for 2 weeks so pardon me for my slow responses , been a good discussion though.

Merry Xmas everyone.

BigE

[scottar]

The cavitation plate is a foil. It generates lift. How else could you trim a motor up or down and effectively alter the boats attitude.
the permatrim foils would give better lift. From basic aviation improvements. Have you noticed newer planes have a vertical fold at the end of the wings. I read that they remove parasitic eddie currents at the end of the wing and generate more lift. Boeing also claim up to 4% fuel improvement. Increasing wing span also induces more lift but the eddie currents on the wing tips also can increase drag.
so have permatrim been through a proper mathematical calculation or was it just a , nah, that looks about right? Lol. The Se400 looks like a larger wing area but those rubber boots over the bolts would create some drag, i would think.

I think if somebody wants to invent a better mouse trap, there is an opening.
Another variable is size/weight of boat. Would you use a larger wing area for a larger boat? If the motor is a weakling, would you use a smaller wing? Could these variables cause people to have different results?
have i opened a can of worms? Hahaha

As a secondary function - yes. The primary reason for the Anti Ventilation plate is - as per it's correct terminology,to prevent ventilation of the propeller. How to trim without it - variation in thrust angle. Downside to that of course is that the more thrust you use for trim (lift), the less of what is available is actually pushing you forward - vectors at work. If by addition of an external aid (tabs or foil) you can run a more efficient thrust angle with the hull itself working more efficiently but you haven't added enough drag to negate any gains - you win as far as economy is concerned.

My statement as per plate extensions was more to do with the cross sectional design of the foil front to back - some, like the Stingray and SE series are shaped like a wing http://4.bp.blogspot.com/-qe5-R-QQ0JI/USpdfZKkpUI/AAAAAAAAAuY/7xQa4qTkgSc/s640/airfoils+shape+effects.gif

The permatrim does have the down turned sides - which as per their marketing stop loss of thrust - quite possibly making some gains but personally I suspect more so to provide strength but front to back it is flat - a slight bevel on the front for drag reduction is about as complex as it gets. There is another subtle fold down the centre line - possibly to better accommodate AV plate design or increase rigidity. Thus it's design doesn't use the same principles to create lift. There are some trains of thought that most of the issues associated with foils are due to some generating too much lift - poor design or poor choice - you could argue that forever. I have never experienced the problems others have so really can't comment.

Better mousetrap - yeah probably but as with anything it's reward for effort.

Foil choice - have a good think about what it is you are trying to achieve - little bit of lift or a lot. Some don't suit some hulls - that can only be found out the hard way or by learning from others mistakes.

Can of worms.....maybe but more likely a hole in the ocean to pour money into ;).

[stevej]

no ones talking about the negatives or downsides
loss of top end speed
having the fin dig in at speed when hitting wake or waves( a truely shit your pants moment)
a following sea where you are not planing and the tendency for the following wave to act upon the foil and make a boat broach
more load on pivot tube and trim gear

there are some positives but they all are just masking a inadequacy

[scottar]

They have been mentioned but I guess they are only downsides if you experience them Steve - obviously not everyone does or the positives outweigh the negatives for their application. What percentage do could be argued to be very small if the responses are anything to go by. Yes there will be more load on the pivot gear and trim rams for sure but it certainly has never effected longevity in my boats. Last motor had a foil from it's second run to the day I sold it in various formats - owned it 20 years and in the pre wife and kids days it did a lot of hours - only T&T repair was corrosion based. Maybe I've been lucky with the broaching, maybe I drive like Miss Daisy but I've done it in some bloody horrible conditions without issue. I suspect that without the foil, that tinnie would have been full of cracks given the use it got - it never got one. I did experience a really good broach in that boat - but when you decide to have a crack at surfing a tinnie with a keel down a swell on SPB for shits and giggles...…..let's just say it had more to do with the loose nut behind the wheel. Young , dumb and full of stupid ideas. Masking an inadequecy - perhaps, but everything in life has those - I'd love my Landcruiser to get 4litres to the hundred like a Prius but it still needs to tow my boat - inadequacy or unrealistic and outside it's design brief??. Sometimes you just have to find the best balance that suits you - a foil can be a budget conscious way of doing so.

[Andy56]

no ones talking about the negatives or downsides
loss of top end speed
having the fin dig in at speed when hitting wake or waves( a truely shit your pants moment)
a following sea where you are not planing and the tendency for the following wave to act upon the foil and make a boat broach
more load on pivot tube and trim gear

there are some positives but they all are just masking a inadequacy

Loss of topend speed? If the cav plate is above water on the plane, how does it affect anything at all?
fin dig in when hitting a wave at speed? I would have thought that the bow cutting through and the hull on the plane would minimise any movement.

your last one , a following sea, i have no answer. I suspect the rear of the boat under power would have a constant bouyancy thus negating this effect. The margin of error fitting an oversized foil is rather unknown.

Everyone agrees trim tabs are the ultimate. And they work by acting on the hull leaving the motor to just push along. Foils on the other hand use the motor to brute force the hull. I guess thats whats the issue, as to whether the brute force does anything untowards. The main force being a vertical lift of the motor. with the hull on plane I would assume, there are less stress forces at play all around anyway. You want just enough lift to get the hull on plane but not so much your motor trim has no effect. So round in circles i go, doubting my initial doubts.
Ebay has them for $120. Also just read, the SE will not fit on an ETEC. Any experience?🤔

[billfisher]

no ones talking about the negatives or downsides
loss of top end speed
having the fin dig in at speed when hitting wake or waves( a truely shit your pants moment)
a following sea where you are not planing and the tendency for the following wave to act upon the foil and make a boat broach
more load on pivot tube and trim gear

there are some positives but they all are just masking a inadequacy

Well I have had one on my boat for 28 years and it does all the things foils are claimed to do, planes at lower speed, planes quicker, easier to keep on the plane in rough seas, improved fuel consumption. I haven't experienced any of those negatives, except maybe loss of top end speed (not that relevant in a fishing boat).

Very simple and cost effective in my case - I am not quite sure why you would dismiss them as 'masking an inadequacy'.

[stevej]

its not an attack on anyone in particulars boat ,people get riled up that any counter view is an attack on their manhood or something worse.

These things can happen as a result of fitting a foil I have experienced the downsides to them so will let others know.
because It hasnt happened to your boat doesn't mean it cant occur.

a boat with enough hp shouldn't need it, add in overloading and the bloat that happens over the years of adding a live bait tank or 2 more batteries and you start to have issues
then you have the issue of people or dealers fitting minimum hp or just poor hull design happening as well
those are what i mean by inadequacies being covered by the foil

[catshark]

Agree that these foils would have many benefits, and i too have experienced the following sea picking me up and trying to broach me when i installed a foil to generate more lift etc etc. would i put another one on ? Yes i would .

[blacklab]

its not an attack on anyone in particular boat ,people get riled up that any counter view is an attack on their manhood or something worse.

These things can happen as a result of fitting a foil I have experience the downsides to them so will let others know.
because It hasnt happened to your boat doesn't mean it cant occur.

a boat with enough hp shouldn't need it, add in overloading and the bloat that happens over the years of adding a live bait tank or 2 more batteries and you start to have issues
then you have the issue of people or dealers fitting minimum hp or just poor hull design happening as well
those are what i mean by inadequacies being covered by the foil

That's a very valid point stevej, about after added weight, So really, , It's just your poor word selection "masking inadaquacies" that maybe gets people riled up ? If any one really did ? I think they just said it hasn't happened to them.
Not many people after the purchase of a boat, can afford to swap out to another motor, So we look for options.
It seems that there are many that are happy with the results of foils, so, why would anyone be anti if it works for them.
It's not about a counter view, when someone gets nothing but a good result from using a foil, then be asked about, reduction of top end speed, bad broaching, having the fin dig in, PERHAPS, just perhaps, your not hearing about the negatives, because those here that have them on, aren't experiencing them ? But I think most are aware of potentual issues, but they aren't set in stone.

As Scott has said, maybe 3-4 times now, it's a case of trying them out and fitting the right one to your hull that works.

I'm not saying that these bad traits wont happen, BUT, because there are many set ups with foils, that are successful, there are no true rights or wrongs until you actually fit one up and test it out on your own hull, trial and era
I guess some are open to this,,, and some are just dead against the whole thing.

col

[billfisher]

its not an attack on anyone in particulars boat ,people get riled up that any counter view is an attack on their manhood or something worse.

These things can happen as a result of fitting a foil I have experienced the downsides to them so will let others know.
because It hasnt happened to your boat doesn't mean it cant occur.

a boat with enough hp shouldn't need it, add in overloading and the bloat that happens over the years of adding a live bait tank or 2 more batteries and you start to have issues
then you have the issue of people or dealers fitting minimum hp or just poor hull design happening as well
those are what i mean by inadequacies being covered by the foil

Well the faults sound a bit far fetched, except losing a bit of top speed. Broaching might be an increased risk but I thought that would be the result of too much lift making the bow more likely to dig in, but if that was the case then probably the boat didn't need a foil in the first place.

As you mentioned foils can be very useful if the boat is in any way underpowered. So even if it is 'masking an inadequacy', so what if it works? Certainly cost effective compared to repowering.

[stevej]

far fetched ? can have that view if it fits your beliefs

I have had It happen on a under powered tinny with a small permatrim in the Parramatta river
full speed and crossing a river cat wake at a angle, the foil dug in boat snapped sideways and up on its side taking on a fair bit of water
this happened twice so I removed it and never happened again , I eventually fitted a 25hp as that was max hp for the hull

also had sketchy experiences in following seas with foils that were fixed by removing the foils


go and spend the 100 bucks all im saying is that there may be unintended consequences and just be prepared for it

[blacklab]

A lot of "sketchy experiences" can also be put down to "Sketching skippering"! foil or not.

I can make any boat broach, and also dig in prefusley if crossing a huge wake, especially a little tinny !.
Trim tabs down in a following will have you submarine in a quick fashion.
You drive to conditions, and as you said, which is what everyone else has said, you fit one to suit your boat, trial and error.
Just like some boats have some horrible traits, you drive to suit and make compensations to suit.
But I can believe that some boats, wouldn't suit a foil, but a bad experience in your boat, doesn't make it the rule for other boats.
I would think a foil on a small tinny, would have a more dramatic effect on handling though, than a 5-6.5 meter fibreglass.
Again, horses for courses, but was an easier fix, out laying for a 25 hp engine, rather than a 150-200 hp.
Most here that have commented, aren't necessarily compensating for an under powered motor like you were,
Did you try another type of foil ? to see if it changed at all, or was it a one try and stuff that ?
I do believe, again, that it has been mentioned here time and time again by a few, you need to try different foils to find the best suited to your hull.

In conclusion, I don't think there's any one here that has a foil on, that's not aware of the issues they "could" cause, but I suspect the benefits they are getting, they are prepared to compensate in there driving to allow for any potentual bad traits that it could bring, if any at all.

Col

[ozscott]

One thing a foil does very well (and in no way is the fitment for this purpose compensation for a shortcoming) is to reduce the clean planing speed allowing the boat to hold its plane (and therefore hyrdonamic lift and stability caused by the planing) at a speed better suited to poor conditions.

Cheers

Sent from my SM-G960F using Tapatalk

[NAGG]

no ones talking about the negatives or downsides
loss of top end speed
having the fin dig in at speed when hitting wake or waves( a truely shit your pants moment)
a following sea where you are not planing and the tendency for the following wave to act upon the foil and make a boat broach
more load on pivot tube and trim gear

there are some positives but they all are just masking a inadequacy

Now you could be talking about boat driving skills ...... I 've seen blokes get in a horrible mess in a following sea when they have their motor trimmed too far in - both with & without foils.

Chris

[billfisher]

far fetched ? can have that view if it fits your beliefs

I have had It happen on a under powered tinny with a small permatrim in the Parramatta river
full speed and crossing a river cat wake at a angle, the foil dug in boat snapped sideways and up on its side taking on a fair bit of water
this happened twice so I removed it and never happened again , I eventually fitted a 25hp as that was max hp for the hull

also had sketchy experiences in following seas with foils that were fixed by removing the foils


go and spend the 100 bucks all im saying is that there may be unintended consequences and just be prepared for it

Well I don't think it's good skippering '
full speed and crossing a river cat wake at a angle', Foil or no foil a small tinnie is going to react adversely. You should have slowed down and taken the wake head on.

Tends to cast doubts on your other claim of broaching in following seas. Perhaps it was poor driving as well. The idea sounds a bit far fetched ie 'following waves acting on the foil'. A following sea will tend to push the boat as it has the whole stern to act on. The trick is to have enough up trim to stop the bow digging in and an appropriate amount of power to maintain steering.

[Dignity]

Big E, can you relabel this post as "foils - urban myths or not" reckon it'll go to 18 pages but hoping not though as the popcorn has run out and beer supplies getting dangerously low. 😉

PS, this post from 2006 only went to 3 pages 😅
http://www.ausfish.com.au/vforum/showthread.php/65572-Hydrofoils-Permatrim-or-SE-sport-300

[scottar]

Oops.... my bad.😂😂

[stevej]

mid river wakes are nothing serious closer to the shore they are quite large and full speed on a 15hp and that hull is only 35-40kph
i continued to drive like that 3-4 times a week during summer over another few years and no issues with the foil gone and even greater hp

all i am saying these things can happen.
dont really care what people think about my skippering i use mine more then most 2-3 times a week and am comfortable with my boats

[blacklab]

Scott,
Whats your opinion on mercury's use of the command thrust gearbox, in particular to there 115 hp size, which is effectively using the same
gearbox as there 150 hp, which means it swings a much bigger prop. From what I've heard about them, there advantages are to give more bum lift, and suppose to push it up on the plain quicker etc etc ?
I ask this, in relation to the discussion on foil/tab advantages.
One of the things I struggled with, with my previous set up with the reef finder, hole shot was never a problem, was getting it to nose down in that certain wave set, which meant on/off the throttle all the time and trolling at that certain speed which it just liked to sit down in the arse all the time. There was nothing wrong with the power to weight with the old 125 4 cylinder Merc, but just couldn't get the boat to sit right at that 8-12 knott trolling speed and was horribly un economical being a 2 stroke. I was always going to try putting tabs or a foil on, before the rebuild had to happen, but now I'm getting close to working out the transom fittings and indeed which motor to slap on, these command thrust models are spruking my interest.
just interested in opinions of there benefit with this option..

Col

[scottar]

Guess it's along the same line of the Zuke's just a different way to get there - bigger prop doing less revs being more efficient - at a guess due to less slip in the mid RPM range. Similar to what I found with my last prop choice - less top end though and the efficiency pretty much draws even at high RPM if that's a concern. A foil, tabs or possibly even both depending on just how slow you want to get up on a clean plane should help for sure - whether you will get as low as 8Knots though in a glass rig is debatable and probably very dependent on hull efficiency as well. On the 4.5 tinnie it wasn't an issue but the Vic minimum efficient clean plane speed is about 18 knots - below that I have so much tab and negative trim on that the fuel burn starts to creep back up.