Hydrofoils on cat outboards

[wadeo]

do we or don't we put hydrfoils on cat outboards?. I use them and have had no probs so far. these outboards had them on when purchased from dpi and were on back of noosa cat which was used for hydrographic servey. Naturally i left them on. Can anyone give any pro's and con's on wheather to use them or not. and why/why not
cheers Wadeo

[Lovey80]

Wadeo, thanks for starting this thread I was going to do the same. Will be watching with interest.

Cheers Chris

[Fish Guts]

wadeo,


i asked the same question a while ago. i got slammed by a few 'armchair experts', but should give u a general indication. about 2 months off putting on permatrims.

http://www.ausfish.com.au/vforum/showthread.php?t=66083&highlight=permatrims

cheers

fish guts

[hungry6]

I got them on mine also and they so far they havent tried to kill me, but then I dont go and pull a 360 turn at 30knots. i believe in general "good' hydrofoil are a plus and 'bad" hydrofoil are a liability. it comes down to how they are made a more importantly are they sturdy enough for the task. the one I got are "extremely" ridgid. I can stand on one side of the wing and not deflect them, but then i'm pretty skinny.

[wadeo]

thanks guys i must have missed previous thread on this but am seriously wanting to now why i shouldn't use them or why i should use them. hopefully this time it stay's on track. If i new the anwser i wouldn't be asking. I have used them for around 100hrs now in all sorts of conditions ( se sports 300 ) and find them ok. some of the more experienced cat owners may be able to shed some genuine light on the subject for us hopefully.
wadeo

[wadeo]

I got them on mine also and they so far they havent tried to kill me, but then I dont go and pull a 360 turn at 30knots. i believe in general "good' hydrofoil are a plus and 'bad" hydrofoil are a liability. it comes down to how they are made a more importantly are they sturdy enough for the task. the one I got are "extremely" ridgid. I can stand on one side of the wing and not deflect them, but then i'm pretty skinny.
thanks h6 I don't try any of those 360 turns either and have realy pushed the boat in every which way in rough seas and so far i'm still here too. I have noticed lots of blokes don't use them and was wandering what difference they make with them or without them when trimming each motor idividually.

[Getout]

Hydrofoil gizmos reduce ventilation by enlarging the cav plate and stopping the sucking of air from the surface by the prop. Cats like plenty of outboard trim. Foils have got to be useful if used carefully.

[dfox]

Wadeo, have you tried your boat without them to see the difference in handling? ...foxy

[hungry6]

I have found that the ones on mine makes the boat 'more' trim sensitive and the rear end sits in the water a fair bit better in choppy conditions, dunno about fuel usage, as I really dont care much for fuel usage, and there will be ppls that will say otherwise, but this is my 'personal' experience. I took them of for a run during the last summer trolling for macks found that the boat doesnt react-behaves as nicely without them, and have to say the way I prefer my boat handling maybe very different to others, who knows, but I'm happy with what it does.
Ask the old man with the bald head, he knows abit more than me.

[wadeo]

Wadeo, have you tried your boat without them to see the difference in handling? ...foxy
Dave no i haven't. I haven't driven it without them at all. If i ran some tests what characteristics in handling and performance should i be looking for ie: Will the nose trim higher? Will it be more responsive in trimming outboards together and individually? Will it drag its ass without them possibly resulting in drowning an outboard? you see alot of cats around like mine with air breather hoses off the top of there coulings i don't have that prob with the hydrofoils. Do you run them Dave?

[wadeo]

thanks for ya input h6. Great to hear another skipper's point of veiw. Especially because youv'e performed these tests already.

[Grand_Marlin]

G'day Wade,

Your boat shouldn't need them, only experimenation with and without them will tell you what works best, as each type / brand / size cat will react differently.

I am not a fan of them usually, but they do have their place.

Hungry's boat responds well with them - heaps of positive bow up trim, and excellent response to lateral trim... albeit that you can lay the boat right over when underway by small adjustments in lateral trim.
It certainly makes you concentrate when driving it... and it certainly makes me nervous when Hungry is driving it, as he is quite happy to run at 30 knots with the boat hanging on a 45 degree angle !
In this case, it has taken a boat that did not respond well to trim, and has made it super responsive to trim.

The thing I hate about foils is they can make the boat "track" ... talking laying on the side, not actual heading deviation.

It is a very real concern, especially in a cat, that if it lays heavily enough on its side, that the foil can make it keep going and scare the crap out of you as it tries its hardest to tip over.

This is especially evident when running 3 quarter ways down large swells, especially if the port side is down sea due to the wind up from the props (assuming you dont have counter rotation) Counter rotation helps a lot.
As you get to the bottom of the swell, yu would expect the boat to level up, when in fact it often keeps on going at the same sideways angle.

The smaller and lighter the boat, the more affected it will be ... this goes hand in hand with pontoon / sponson design as well.

Your 23ft boat which weighs 3 tonne will not be as prone to the bad effects of the foils, mainly due to weight.

I always try to avoid them unless there is a real need.

Cheers

Pete

[hungry6]

There you go, the old man with the bald head made a reply.

What I might do is organise a night where we can grab a few of these "experience" cat ppls to do a "SHOW & TELL" to all of us wannabe cat drivers even though we own cats, I've got the venue, just got to get time to get it together.

[northernblue]

Please excuse my small hijack,
I had been lead to believe that counter rotating motors were not really deemed required "nowadays" [in cats].
Is the [reduced] tendency to bury the port bow the main [or only] reason for counters?

[finding_time]

Please excuse my small hijack,
I had been lead to believe that counter rotating motors were not really deemed required "nowadays" [in cats].
Is the [reduced] tendency to bury the port bow the main [or only] reason for counters?

The other reason is to allow both engines to work as hard as each other, with non counter rotating props one engine is always working harder that the other and is quite noticable when driving.

ian

Ps. Great post pete;)

[freddofrog]

When I first got my 5.2KC it came with hydrofoils and after a few runs I took them off.

Safety was one factor in terms of all the stories you hear of boats rolling or almost rolling for no apparent reason other than they have foils on them.

The other reason was I found they lifted the stern too much which then had the effect of forcing the bow down. (which is what they are supposed to do) This caused it to really plow through the water so until you had it trimmed out (as others have said) and planning it was just hard going.

I may try them on again later when I really get some experience under my belt but for the time being it's not worth the risk.

cya
ff

[fishingrod]

I was running SharkCat 700 with twin 175hp Yammys. (non c/rotating)

I might have done around 100 hours with no foils, and then 100 hours with PermaTrims fitted. Cant say I noticed any difference. It handled fine with and without. The thing was plenty fast enough so I didnt really notice any speed difference in smooth seas.

It was a work boat and someone suddenly decided to fit them one day ..... apparently (and i stress not my idea) they were meant to reduce the mist/spray getting sucked into the cockpit. We never had a major problem with mist in the first place.

I cant say i was convinced that the PermaTrims did anything good or bad.

cheers
Rod

[Fish Guts]

could you plane at lower revs rod ?

[wadeo]

some great info coming out here, Keep it coming guy's. Great idea h6 a show and tell would be good. i have a counter rotating gearbox so engines alway's working together. Would my outboards be prone to more spray as a result of taking foils off? putting ass further down in water under travel.
Wadeo

[fishingrod]

could you plane at lower revs rod ?

I cant say i noticed, sorry. Adding the PermaTrims didnt transform the boat into anything obviously different. I never really ran it for long periods around the just-on-the-plane speed so cant really comment. The cat always lifted smootly onto the plane with no bow-up attitude like some monos. The transition was barely noticable.

Rod

[Grand_Marlin]

Please excuse my small hijack,
I had been lead to believe that counter rotating motors were not really deemed required "nowadays" [in cats].
Is the [reduced] tendency to bury the port bow the main [or only] reason for counters?


Not true,

Any twin engine powered boat, cat or mono, no matter how new or old, will be a completely different boat with counter rotating motors.

It is a very noticeable difference .... with c/r the boat sits flat in the water, is a lot more stable and predictable underway ... all the inertia is projected forwards, instead of partially sideways (if that makes sense)
In a lot of cases, c/r motors would cancel the need for trim tabs for lateral trimming.

Cheers

Pete

[Kerry]

....It was a work boat and someone suddenly decided to fit them one day ..... apparently (and i stress not my idea) they were meant to reduce the mist/spray getting sucked into the cockpit. We never had a major problem with mist in the first place....

But who ever thought of that idea was a bit misconcieved, as a foil will not achieve that aim anyway. Oh yes it's good to see they were trying to fix something that didn't exist :)

Spray deflectors a generally fitted above the gearcase join and fixed to the lower body of the leg not the gearcase section. At this height they are never in the water to cause any issues that cats are infamous for with foils fitted.

[Noelm]

as a general observation (and I have worked in and owned many different cats) if the boat is well powered and setup, most "add on" foils do little at all, in some cases of just enough power they CAN, MAYBE, help a tiny bit in getting up on the plane but not a lot, counter rotating has little bearing on foils or no foils, it is more to do with steering and list (especially in a mono)

[wadeo]

Noelm would you think that with out them i may have problems with drowning outboards? I know you don't now my boat or how its weighted but they were known to drown outboards occasionally from dragging their ass through the ocean. As already stated i don't have this prob with mine and have pinpointed that down to the hydrofoils as well as putting air tight pods on the transom as well?What disadvantages would be eminent having them?

[dfox]

Dave no i haven't. I haven't driven it without them at all. If i ran some tests what characteristics in handling and performance should i be looking for ie: Will the nose trim higher? Will it be more responsive in trimming outboards together and individually? Will it drag its ass without them possibly resulting in drowning an outboard? you see alot of cats around like mine with air breather hoses off the top of there coulings i don't have that prob with the hydrofoils. Do you run them Dave?

No mate, mine doesnt need any rear lift, but id be interested how your boat performs without them. If the rear rides a bit deep theres always the possability of 4 bladed props to gain lift ...

[wadeo]

thanks dave i'm going to run some tests over the next few trips. Good point about 4 blade props.

[Noelm]

wadeo, not too sure about drowning outboards when under way, some had some problems putting them on and off the trailer, and maybe reversing in bad conditions, but not too many(I would think) lost a motor when actually motoring along, and kerry is also correct, a properly setup motor will NOT have the foil anywhere near the water level when on the plane, but I guess it could have some adverse reaction if it was to somehow "dig in" at a slower speed and maybe somehow drag that motor down, a lot of somehows and what ifs there though!

[Big G]

Hi,
I fitted se sport 300 foils to 140 4strokes on a 6mt. Jaycat for no other reason than I wanted to try them to see if the boat improved any handling charactics. I was new to cats and I thought that I may improve turning on flat water.... after fitting them I found no change in turning. After I changed my driving by increasing power to the inside engine on a turn, any opposite lean on turns disappeared.

I did loose top end speed from 38knots to 33 knots.... so yesterday I did a run in the bay in flat water with the foils still on at 5300rpm 33 knots... went in to Horseshoe bay and removed them I then re-run and checked performance in the same direction and conditions and recorded 5500rpm at 38knots.

Flat water turns were fine with or without foils as long as I increased throttle on which ever engine is inside the turn. That is opposite to what you think but the extra throttle pulls the pontoon down hard and levels the boat out during turns. This takes away the cat charactistic of leaning the opposite way to a mono in turns and feels great. This effect may have been marginally better with foils but not worth the loss of fuel economy and top end caused by the extra drag.

I am now under the impression that if the cat is set up correctly it will perform well without foils. I am going to leave them off and do some outside work and revaluate their use.

The Jaycat never suffered from engines being splashed with water, misting into the cab or lift problems. I think the extra length of the tunnel past the outboards puts all those problems behind the boat.

Big G.

[Grand_Marlin]

What aboat the effect on trim Big G?

Especially the sensitivity to trim / lateral trim effect?

Cheers

Pete

[Big G]

Hi,
I noticed little difference to lateral trim except that the sensitivity was reduced with the foils removed. The amount of trim has not decreased but the difference between bad trim and good trim has widened. I find this better as the trim position without foils is less critical. With foils you had to continually adjust trim as sea conditions changed and only so slightly because of increased sensitivity. Without foils I just set the trim between 2/3 and 7/8 on the trim gauge and the hull is happy. Trim position appears less critical without the foils.

I don’t bother trimming in for standing starts just set about ¾ on trim gauge, open throttles to about 1/3 and it quickly gets up on the plane ending up at around 3200rpm and 16/18knots increase to what ever revs I may want to travel at and maybe increase trim to 7/8 on gauge for anything over 25knots. The less trim adjustments I need to do the more I can enjoy the scenery and concentrate on the sea.

Before fitting foils on my first outside trip I was in a moderate following sea and totally inexperienced with cats. I had two adults seated forward of the cabin, a no no in a small cat (6mt.) yet it performed ok with just the slightest uneasy feeling driving down the face of the following sea. After experimenting with foils and driving technique I soon learnt that Cats love maximum trim out and plenty of aft weight.

Anyway I will soon know what is best, with foils or without foils. Due to the loss of speed I will forgo the trim sensitivity which I don’t think is an advantage as you have to concentrate too much to get it right. Without foils it is set and forget.

Cheers
Big G.

[wadeo]

Big G thanks for posting info on. I'm taking my foils off for next trip and will post my findings also. sounds like an advantage on fuel without them as a bonus. Interested on your veiw after you have run ya rig offshore as well.

[cormorant]

But who ever thought of that idea was a bit misconcieved, as a foil will not achieve that aim anyway. Oh yes it's good to see they were trying to fix something that didn't exist :)

Spray deflectors a generally fitted above the gearcase join and fixed to the lower body of the leg not the gearcase section. At this height they are never in the water to cause any issues that cats are infamous for with foils fitted.


Hi What are the "Issues with foils attached to cats ". Following seas broaching ???
C

[Big G]

Coromant,
I think the problem is giving a cat hull more lift than is required. The lift needs to come from the pontoon design rather than from the foils otherwise the hull sits flat or nose down and in a following sea cats prefer the sturn tucked down and the bow up.

This is a pic of the Jaycat at 35Knots without foils......with foils the hull sits flatter to the water and was slower.
But like I have said I'm still learning and my opinion could be wrong.
I would love to hear from other cat owners.

Big G.

[Smithy]

I had typed this out a couple of weeks ago when the discussion first started but I stupidly lost it. Anyway here goes again retyped. Probably forgot some of the points.

My experience with cats with foils has all been to do with cats at the lower end of the spectrum. The first one I saw with one was Matt Mott's 4.3m Webster Twinfisher Kahuna Kat, in survey for freshwater charters with a 4 stroke 50 Merc. He had an SEsport on it to assist getting onto the plane. The 4 stroke weight plus a full load of customers saw it struggle onto the plane sometimes. The SEsport was suppossed to have the least amount of handling vices.

He continued with the SEsport on his 4.6m Webster Big Kahuna. It had a 75 4 stroke Merc on it so a fair bit of weight and this was in survey for 4+1. It had the same issues and the 75 is basically a detuned 115 with regard weight and block etc.

The other week I test drove a 5.0m Sailfish in survey that sported twin Honda 50 4 strokes. That bloke had Permatrims on. I asked him about them and he said it really suffered from motor torque. Counter rotation could be the biggest point and was talked about above. He needed a bucketfull of trim on the one side to keep it upright without the Permatrims. They seemed to be working for him.

Now the interesting one was Jason Rhodes' 4.3 Raider Cat Little Stooge. Jase had done it up to the nines with 6m Reelax poles, teak gunnels, Reelax HD rod holders, padded coamings, Vibac clears, 10" colour sounder etc. It sported twin CV 50 Yammies but with 50 High Tech cowls. He had a bad run on his previous 10m Noosa/Shark Cat Stalker which sported 225 Yammie Offshores and them doing oil pumps and blowing up under warranty so he wanted the simpleness of premix after that experience. Stalker was a work of art he rebuilt and made into a gamefishing weapon, an express layout with Black Marlin Towers Tuna Tower. Little Stooge he built as a joke to win the trophy for number one Marlin boat on the Gold Coast which he did the year it was built with his then GF Jodie winning champion angler from it. Now it sported full width alloy pods he had made himself and it sported twin Stingray Junior foils. Now with Jase being a cat man through and through and with all his boating contacts on the Gold Coast and being a real performance man I found this strange. He obviously thought they worked or they wouldn't have been there. Power was fine, 100hp on a 4.3m boat. It was only ever really an 18 knot sort of boat anyway and got a bit flighty above 20 knots but an awesome little seaboat that he got caught out in a couple of afternoon summer storms in and lived through quite safely.

Finally my mates with the 5.9 Ambition Cat Two Up which are now marketed as Commander Cats tried a few 2 piece foils on the twin 75 Honda 4 strokes it sports. They tried one half on the outside of the two motors and full foils on each motor. Verdict was they did get the nose pushing more water but they made no difference. Same verdict as Big G it would seem. They took them off.

I think from those little stories it seems to be a small cat/big cat thing. If your cat is setup right with ample power there is no need for them. That is where cats like 5.2KCs and the 5.9 Ambition I have been in and stuff are good, no real dead spot or planing hump like monos. Just put the throttles where you want and off you go.

[wadeo]

gday Big G and Smithy thanks for your useful info. I'm yet to do my tests as weather is not flash but have to drive mine from brissie river to moloolaba in next week or so. i plan to remove foils for this trip and will report my findings. big G how have you found your cat handles offshore now.

[soulfish]

hey wadeo just curious if you tow your cat from time to time and what vehicle you use.i seen a pic you posted on a trailer.nice boat by the way.

cheers jason

[Smithy]

So here are Big Kahuna the Webster, Little Stooge the Raider Cat (Steve Ausfish Brown acutally snapped that one picture on the water of it from my boat - Jase went 3-3-3 on Blacks that day solo) and then Stalker. The owners after Jase must have got rid of the signwriting. I saw those pics pop up on Boatpoint.

[wadeo]

hey wadeo just curious if you tow your cat from time to time and what vehicle you use.i seen a pic you posted on a trailer.nice boat by the way.

cheers jason

Gday Jason.It lives on the trailer now and i tow it with a 99 Nissan navara single cab. It tows ok after beefing up the diesel 3.2l with after market turbo etc and stronger suspension. The trailer is braked on all 6 wheels and i only live 10mins from the ramp (no hills). 6 weeks ago i towed her to brissy for some repairs and vouched i'd never tow it that far again especially with the road trains blowing ya around.
Wadeo

[wadeo]

Some nice cats there smithy.

[Dean1]

You might have to buy yourself a primemover wadeo ;D . Gee my rodeo tows my kc good, bout 500kgs lighter than the old platey 8-)

[Dean1]

Hey wadeo my old cat had foils on it when i bought it so i just left em on. It got up and boogied very quickly and did everything else fine, id just take em off next trip mate and see how she goes, trial and error. I might be following you hopefully, i might even keep up now! ;D

[wadeo]

Hey wadeo my old cat had foils on it when i bought it so i just left em on. It got up and boogied very quickly and did everything else fine, id just take em off next trip mate and see how she goes, trial and error. I might be following you hopefully, i might even keep up now! ;D

You'll keep up now deano for sure. I noticed ya multi cat had foils on it. As soon as i get it back i'll rip the foils off and test her out. Intreged to see the difference.

[23-sharkcat]

Wadeo,

are you sure that you can legally tow that cat with the Navara.

here are some photos of your cat when I picked her up from Bowen.

or and some photos of my 23 cat with permatrims.

[wadeo]

Wadeo,

are you sure that you can legally tow that cat with the Navara.

here are some photos of your cat when I picked her up from Bowen.

or and some photos of my 23 cat with permatrims.
Gday 23 shark cat. Nav can tow 2.8t. The cat is heavier just lucky i only live 5-10min from ramp. Did tow to brissie but give that a big miss in future.Thanks for the picy's did ya tow her home to brissie from bowen? It seems most cats that have permatrims or foils are sharkcats or noosa cats

[Thebuffalo]

Interesting thread. I have a 7.5m Sailfish which doesn't have foils fitted. The boat is designed for about 150hp per side I think but is powered by two 175hp opti's.

I have to agree with most of what you fellers have stated already. I think the most important point raised was horsepower. Would it be fair to say the main reasons for the foils etc is to get the boat on the plane faster and at lower speeds.

One thing I don't normally do is travel slow other than when I am trawling and being a cat you never have to slow down that much for the sea conditions (well maybe sometimes)

When the boat is heavily loaded the horsepower seems to overcome any bogging down in the rear.

Would be interesting to know if the savings in fuel and the sensitivity to trim would make it worthwhile to fit them.

Just my 2c.

[Dean1]

Yes makes sense buffalo, I dont think cats really need foils, especially if there powered properly. Like you said you rarely have to slow down. One thing ive noticed with my new kevlacat is that it has these plates bolted onto the legs, not the cav plate. When i was buying this boat the fella told me he has never had spray come into the cabin, sucked back in as some cats do, i didnt believe him but this cat is so dry it doesnt suck spray back in at all! Ive been in 2 other 5.2 kc"s and they were both wet boats and didnt have these plates on them. Maybe these are neccessary on cats?? Heres some pics

[wadeo]

Any idea where these plates can be purchased deano or any one else?I noticed i've got holes in same position with duralac around them but the plates are missing

[Dean1]

Wade ive got no idea where you get these plates from mate, our mobile mech. wade would know i reckon..

[Outer Edge]

Wadeo,

You should get in contact with Noosa Cat im sure they will stear you in the right direction..I am led to believe they are called spray plates apparently there purpose is to deflect excessive water ..;)

They fitted them to the 5.2 m Noosa Cats with the wedge designed hull at the stern.. The wedge was designed to improve trim and prob did , however it did increase the amount of water stream being throwen up the leg/motor. This in turn becoming more mist/spray.

A mate of mine purchased a 5.2 Noosa cat many years ago and i asked the same question .

Dean 1 , mate the next time you go for a run in your KC (love your rig mate);D pop down the back and see if you those plates are doing the job of containing the water , if you have`nt already.

Also if you have a look at the Photo that Dean 1 posted of the rear shot of his KC there is only a small step up from the bottom of the hull to the bottom of the pod.

The 5.2 Noosa cat had no pod,just a transom. This cut out or (wedge) taken out of the hull was far greater so it forced more water up.

Outer edge.

[wadeo]

thanks for info outer edge will give noosa cat a ring and find out for info.
cheers Wadeo

[wadeo]

Gday all finally ran some of my own tests today without hydrofoils.Waited till the sea breeze got up the sarvo and went out off moloolaba to see how she would run.Firstly the ride i got with foils fitted was great but alot more boat in the water under trim. Going head on into prob 1.8m of SE sea sitting on 30kn at 3700rpm cat felt lighter with noticeably less boat in the water and more speed at less throttle. A characteristic we picked up that we never had before was nose seemed to jump higher off a wave and catch the wind in mid flight cushoning it as it landed( seems to leep more now).Definatley a different ride that i'll have to get used too. She is just as quick getting out of the hole if not quicker. I expect my top end speed has increased by about 6kn. coming home in a following sea she was as good as ever. No extra spray than normal over outboards. Will still need a few trips to make up my mind fully but today was a great start. Now i have done afew tests i know hydrofoils did make the cat handle considerebly different Ie: more hull in the water with cat working more like a barge. Engines had to work harder in all area's of travel including from floating start. Cat seemed less responsive to trim with them ie. Down side now with out them i have to teach myself to drive it all over again .


regards
Wadeo;D

[lenm5]

Whilst on the subject of motor setup with cats
has anyone had a play around with their motor alignments??
Toe in / toe out or just netural
I wonder what would be the best for a non counter rotating setup?

[northernblue]

So Wadeo, you are saying that without the foils you effectively have better trim control? ie allowing you to trim the bow higher?
If so that is entirely contrary to what I have experienced in monos and would have expected in any boat.

[wadeo]

So Wadeo, you are saying that without the foils you effectively have better trim control? ie allowing you to trim the bow higher?
If so that is entirely contrary to what I have experienced in monos and would have expected in any boat.
Gday Glenn Most Definetley gave me more trim and made bow heaps lighter. I tested it in the same trim position as i would normaly operate it with foils and found that the bow road heaps higher therefore making the boat feel alot lighter as it traveled into a head sea. In some instances riding over larger waves i found i had to back it off a bit at 30kn because i rekon i was now trimmed to high. going to have to learn to drive her all over again because their was a massive difference between with foils and without. Hopefully after a few more trips i will be confident in its new handling characteristics.

regards wadeo

[Dean1]

Hey Wados it sounds like your motors are working alot easier now, making it even harder for me to try and keep up with you ;D Mate sounds like its for the better, youll find youll get better fuel economy now too mate. Gr8 result :thumbsup:

[wadeo]

Hey Wados it sounds like your motors are working alot easier now, making it even harder for me to try and keep up with you ;D Mate sounds like its for the better, youll find youll get better fuel economy now too mate. Gr8 result :thumbsup:

Gday deano keen as to take it for along run still need time to test lat trim and figure out her best riding trim position. Didnt thick it would make as big a difference as it has. Am thinking of getting a second opinion on a sea trial with another experienced skipper. You'll keep up buddy i very rarley open her wot.

[wadeo]

Whilst on the subject of motor setup with cats
has anyone had a play around with their motor alignments??
Toe in / toe out or just netural
I wonder what would be the best for a non counter rotating setup?

Grand marlin might have played around with "twisting engine''s " mine are counter rotating so not sure. I also wonder about 4 blade props

[Outer Edge]

Grand marlin might have played around with "twisting engine''s " mine are counter rotating so not sure. I also wonder about 4 blade props


Wadeo,

Funny you mentioned 4 blade props .... Just got back from a three day run on my mates Coastal Cat as he had just fitted some 4 blades on his rig .....

The findings were , more trim and less cav, more torque, less fuel, with a big payload on board ,in fact slightly more than usual.........However he has lost about 1 or 2 knots...

I for one will now be changing over to 4 blades..


Outer edge

[Grand_Marlin]

G'day Waedo,

I havent played with toe in / out.

I have seen 1 cat that had toe out (prop offset to outside of boat) to supposedly help with turns.

My opinion? Not worth playing with.

Cheers

Pete

[Grand_Marlin]

Ratman has just bought a 560 Sharkcat that has foils on it.

The foils are neither helping anything or hurting anything when it comes to handling / trim.

However, I am sure that they are making the boat more sluggish on the performance side of things.

He is going to try the boat with them off.

I will let you know the results.

Cheers

Pete

[wadeo]

Gday pete will be interested to here how it affects his as with mine there was a huge difference.
regards Wadeo

[Dean1]

I only just noticed the other day that one of my motors toes in slightly. Well a noticable amount. Do you think this would affect its performance pete in any way?? Thanks, Deano.

[mirage]

Those new Glacier Bay Cats from the USA have a sheet load of toe in or out (can't remember which), it's very obvious to look at. Something to do with their displacement hull if I remember correctly!

[Chimo]

Hi

Just noticed your comment re toe in and having gone thru the exercise with my Vag a while ago here is a link to have a look at. It will lead you to others if you want to get into it further.

http://continuouswave.com/whaler/reference/twinEngineMounting.html

Some time ago I was in contact with a Master Tech from the US who used to train staff at OMC that was; and he reckoned it was worth setting motors up with toe in on deep vees and I seem to recall him suggesting that toe out was better on cats.

I will have a look and see if I kept any of the other stuff if that of interest to you.

Cheers
Chimo

[Chimo]

Re the Glacier bays, they may have toe in or out but they also have the motors mounted with the legs offset towards the outside of the boat. Keeps them steadier? or something so maybe they fall over less?

Chimo

[Dean1]

Thanks Chimo, ill have a look into it, i guess its maybe something i might have to experiment with :-/

[wadeo]

I wonder if these set ups are for non counter rotating outboards. dean are both motor's crooked?

[Lovey80]

Has turned out to be a great thread lads. (I actually forgot about it for a while). While I am in a very different situation having only the one engine I was always finding that I couldn't get the bow up enough in the chop (I have a foil fitted). When I did trim out to the point where I wanted it i was too far trimmed and the prop lost water.

I'm going to trial my little Webster with out the foil next time and guage the difference.

Thanks all that contributed to the thread....very informative.

Cheers Chris

[wadeo]

Yeah chris i acheived what your after taking foil off give it a go and let us know your opinion.
regards Wadeo

[lenm5]

I seem to recall him suggesting that toe out was better on cats.

I will have a look and see if I kept any of the other stuff if that of interest to you

Thanks for that info Chimo

I happened to check my cat the other day which was setup by reputable outboard dealer and also found a small amount of toe out (non-counter rotating motors)

When I measured the distance at the leading/front edge centreline of the engines - it was around 10mm longer than the distance across the back of the engines.
Each engine could be seen as 5mm turned out from a true centreline with the hulls.
Id be interested to hear what other people with non-counter rotating have.
LM

[lenm5]

Some pics above for any small cat fans out there of my little number.
Was taken recently after a long uncessful day trolling for stripes:P
It's a similar boat to Jasons Rhodes 'Lil Stooge' - as Smithy metioned earlier.
It's a pity these little cats went out of production as I can vouch for their awesome sea handling too.
I'd love to buy the mould and build some more.
Cheers
LM

[finding_time]

Hey dean

I got an isolator on my hydrolic stearing, i can turn a leaver and only one motor will turn. So if they need straightning all i do is turn the motors till the one that gets isolated is centred , isolate it then turn the other motor to corespond. Doesn't your have this?

I'll be very interested to follow this toe in -out issue always looking for more performance.

Ian

[Noelm]

almost all Cats that I have measured for toe in/out where ALWAYS wider at the rear than the front when measuered centre to centre (of course) and the larger the engine, the greater the difference, maybe been a change in thinking/design over the years and have reversed the early setup??

[wadeo]

Hey dean

I got an isolator on my hydrolic stearing, i can turn a leaver and only one motor will turn. So if they need straightning all i do is turn the motors till the one that gets isolated is centred , isolate it then turn the other motor to corespond. Doesn't your have this?

I'll be very interested to follow this toe in -out issue always looking for more performance.

Ian
Gday finding time i think there called syncronisation valves. Over the coarse of use and also jerking around when trailering one outboard can slowly wander in or out . Doesn't happen that often but occasionaly i realign mine when i notice their out. One way i tell is full lock outboards and make sure both are getting maximum or the same travel each way. also ran another test without foils on wednesday from moloolaba to the Hards. Received better fuel acconomy. think i had it trimmed out too far though as it was banging doing 20kn into a 20 kn Ne head sea. Covered 65km from hards to mouth of rock walls in 1hr5min coming home in shitfull conditions. (Banging!!) should i try dropping nose a touch ??
regards
Wadeo

[Dean1]

LM nice little cat there mate, i reckon she'd run sweet;) Ian i dont know if that isolator is on the back of my steering or not, ill check it out. My motors are toeing in 25mm :o This seems alot i dont know if this is right or not :-/ Ill try alighning them and see if its any different i guess.

[Greg P]

Toe in should lift the bow and tow out vice versa. Lot of mucking around but you could fine tune the little cats by trial and error. You will loose speed but as there is more drag on the legs.

[Dean1]

Ok thanx for that greg that makes sense, i wondered how it affected the ride etc. Like wade said earlier, this can happen from towing etc. I think ill straighten them back up and leave em at that ;)

[cormorant]

Another point. If you have counter- rotators on a boat you don't need the trim tabs at the back of the motors cav plate. You can set your existing ones to a neutral position as with twins Cr there is no torque steer with hydraulic or solid motor links / tie bar. You used to be able when buying a matched pair get a neutral set without the offset on them or you could use the blanks aftermnarket annodes without the tabs on them at all and you might gain an extra .0001 knots!!!

Slight Toe in may lift the bow ( not sure) but I have experienced much more porpoising if done too much when you trim right out. I'll have to have a play and check. Toe out if overdone can make it a worry if you lift a leg out of the water slightly or aerate only one prop as it tries to steer the boat towards the aerated prop - ie into the trough. Toe in makes sense as it is trying to push down the centerline of the boat and has a lesser leverage affect.


Talking of steering in cats many many years ago a bloke was working on a proportional steering system where upon turning the wheel ( on tight turns) the motors moved at different rates to create tighter smoother turns without loosing speed and using all the motors power at the correct vector for the turn. He then also was going to include a throttle link to power up the inside motor slightly so to help stop the lean out affect. That would be 15 years ago and never heard or seen it since but had a good write up in a article at the time. Like all things cat it is easier just to buy stuff designed for monohulls.

Be interested to hear how anyone goes on toe in / out experiments with counter rotators.

The glacier bay cats had a motor mount the instead of having tehmotors vertical had the legs splayed to the outside edges of the hulls. The sales pitch was that the props were then in clear water and as it has pretty fine hulls at the transom for a soft ride it still allowed them to carry heavy motors and not need 40 inch shafts. Interesting concept and never been in one but could imagine toe in / out would be critical on them and it would affect nose up / down trin just like trimming would on a normal cat.

C

Edit post. I think slight toe in on a cat may give it a slightly wider stability "footprint" at the stern while underway and assume it might be more effecient as the flow of water from the tunnel fills the middle section of your wake.

[Noelm]

not too sure how toe in or out can lift the bow (I don't say that it does not) but it seems unlikely (to me) that it could have an effect on bow up/down attitude, anyone got a feasible explanation/proof?? and once a long time ago I did see an old 18' Sharkcat with a pair of lever like "things" that when pulled up moved one motor up a bit, the guy said it was some sort of Offshore racing "thing" made by a Company I think Sea Bear or close to that anyway.

[Noelm]

OH and I think you may mean 30" shafts not 40

[cormorant]

OH and I think you may mean 30" shafts not 40

Hi Noelm

No I meanyt 40's (ie they don't exist). The one overseas I saw had amazingly deep draft with very fine hulls more like a bow than a transon. It was being used as a stable camera platform / chase boat. To do a traditional set up with the motors vertical and in line with the hulls you would have needed a 40 shaft to get clear water under the hull to pass over the props. Video showed that it never surface planed but always had approx 6 inches of this very fine hull botton in the water. Instead they angle the motors abour 15 deg so the the props were in clear water. Wouldn't want to trailer the thing in Australia on our roads with such fine hulls. I have seen a similar one in Australia but the hulls were not as fine or deep at the back but still had the angled motors and props outside the edge of the hull underwater. Looked like a twin engined aircraft when looked at head on below the waterline.
c

PS your not talking about vertical jacking plates are you- manual or electric /hydraulic to change motor depth to get faster hole shot and then lift for high speed.

[Noelm]

nope, not Jacking plates, but something that appeared to me to move the motor as if steered independantly, or trimmed somehow, not too sure what it was claimed to have done or if it did make any difference, but it was fitted none the less, and I now see what you meant by 40" leg! it is also my understanding that Glacier Bay cats are not true planing Boats, but more a "semi" planing design.

[Lunasea]

holy shit, one of the most frightening experiences i ever had was in a test drive of jasons boat 4.1 raidercat with the foils.
it was very sensitive to trim and the foils behaved as para veins, just felt like a submarine. i also believe his pods sucked and lent themselves to poor motor height. if your cat aint working, look to the motor setup, forget foils they are dangerous.

[cormorant]

nope, not Jacking plates, but something that appeared to me to move the motor as if steered independantly, or trimmed somehow, not too sure what it was claimed to have done or if it did make any difference, but it was fitted none the less, and I now see what you meant by 40" leg! it is also my understanding that Glacier Bay cats are not true planing Boats, but more a "semi" planing design.



You might be talking proportional steering. Has been tried on some racing cats where the outside motor and inside motors turn in proportion to the radius of the turn so all prop thrust is directed in the exactly correct direction. I have seem photos OS of a very complicated additional system that also applied trim and jacking to the motors independently on turns. Be frucked if I would trust all that technology at the speed those blokes do into tight turns while racing.

[John Buoy]

Another revived thread and great to see as i was only reading this one last night.
Why because a friend on another forum some of you might know (Firecat)
Has an earlier model $4.9 Markham Whaler which were notorious for porpoising
This particular boat is fitted with twin late model 60 2st mercs and
he desrcibed the ride as nothing else but simply SHYTE in his words.
It was wet ,porpoised at all speeds and cavitated even though motors
were sitting low enough (probably too low)
Since 2 weeks ago when he raised the motors to have the Cav Plt 25mm above
the lowest portion of the hull and fitting a Permatrim
he now needs tissues every time he takes it for a spin
to wipe away the tears of joy.
The boat has transformed beautifully to nil porpoising, nil water over the bow and
top speed increased by 10klph in choppy waters.
Just a case of a small cat where Permatrims worked.
I believe there is big difference between using foils(areoplane wings)
which can bury and dig and trim assisters such as permatrims which can get
a heavy ass ended boat up a tad and keep good clean water aorund where it's needed...on your props.
Here is alink to the thread and pics of fitment

http://vicsaltfishing.forumarena.com/vicsaltfishing-thread1439.html

Regards Frank

[Lovey80]

Another late note for the Webster, as mine is different to all your experiences it may be still relevant.

Without the foil the little 4.3 single engine showed no difference in planning speed until I loaded the boat right up. 4 People big esky with ice beers etc and the live well full. I found that havinging someone move f'ard a few steps until the boat got on the plane to be the best solution then they sat back down the back and it went fine.

The biggest difference is when it is choppy and I want to point the nose up it helps a lot. I have decided that now it has a new 50hp 4 banger that the foil will not be put on this engine. This was confirmed in December when fishing inside the harbour at inskip when a real late notice storm came in.

No joke gusting to 30 knots easy and the bay went from flat as a tac to fairly sizeable waves in no time. I had already made the decision to head back to Kauri creek and there was no turning back and i had offloaded the 2 girls and larger stuff into a mates 7m Stingray. I found that cracking it open to about 5000rpm and getting the nose up as high as i could go before it cavitated to be the best option and i averaged 19kts all the way back to Kauri creek with just me and my cousin on board. The 7m stingray platey stayed with me the whole way but I guess they were no less comfortable than what we were (although we were a lot wetter). I serously doubt now wether I would have been able to 1 maintain that speed or 2 keep such a comfortable ride with only the odd bang with the foil on the back or for that matter with the old 40 on it.

So for me if you have a 4.3m Webster twinfisher don't bother with the foil unless your in the same situation as the guy smithy spoke about and need a heavy load on a dam.

Cheers

[hinchy]

holy shit, one of the most frightening experiences i ever had was in a test drive of jasons boat 4.1 raidercat with the foils.
it was very sensitive to trim and the foils behaved as para veins, just felt like a submarine. i also believe his pods sucked and lent themselves to poor motor height. if your cat aint working, look to the motor setup, forget foils they are dangerous.

Hi
As a matter of interest I bought Jason's boat and would have to admit that it was very sensitive to trim with the foils in place.After the foils were removed the boat improved tremendously in its handling characteristics.The alloy pods on Jason's boat,the first one made, did leave a lot to be desired.Later models were built with larger fibreglass pods of a different shape.
I personally believe that cat's,when setup properly, should not need to have foils fitted to make them handle or ride correctly,just my opinion.

Kind Regards

Hinchy

[finding_time]

Wadeo

Just reread this thread , what the situation now with your motors, hydrofoiled or not?


Ian

[wadeo]

Wadeo

Just reread this thread , what the situation now with your motors, hydrofoiled or not?


Ian
Gday guys i did a few tests with my cat and came to the conclusion no foils was the way to go. when the foils were fitted it was not trim sensitive at all but very doey to reacting to trim at all while wanting to keep its nose down even when triming up. It wasnt till it was traveling at over 40kn that you could notice any differnce in or change to the ride at all when trimming outboards together or seperate. My first trip with out the foils changed the ride and respose in the trim and handling of the cat to the point that it was a completley different boat. The cat felt way more responsive under power, alot lighter while traveling and alot more out ward trim resulting in being able to lift the nose to any position i required. A small fuel saving was also noticed. I found with lateral trim it responds now instantly making the cat work as it is suposed to. I have now done 300hrs without foils and would never put them back on again for any reason. I find now i can travel faster and more comfortable across bigger seas with alot better control. Please take into consideration that i run counter rotating outboards which i beleive plays a huge part of getting the best performance out of a cat. Another test that i have done which is a diffent topic all together.

regards wadeo

[John Buoy]

Wadeo without going back thru each post
can you tell us the brand/type of foil you were using;)

Regards frank

[wadeo]

Wadeo without going back thru each post
can you tell us the brand/type of foil you were using;)

Regards frank

Gday Frank i was using SE SPORT 300 foils. Sold them to aerodauto and he fitted them to his older 7m sharkcat which has not got counter rotating outboards and he is of the opinion that they bettered his performance and has left them on. Another point i forgot to mention was better fuel economy without them and WOT was nearly 400rpm more without foils

regards Wadeo8-)

[John Buoy]

I'm not surprised as i'm no fan of the wing types..:P
Lean and bury a wing can be dramatic in certain conditions in a cat.
Thats where i think the Permatrims are handy.
They are more like an extension to the cav plate as they are longer and narrower
and wont bury but give heaps of
assisted trim if needed and direct clean water back down onto the prop
which helps in planing and cavitational issues and are very useful in heavy arse ended boats particularly underpowererd twin 4bangers.

Was a great comparison with and without on your rig
and glad you found the sweetspot with ypur ride ;)

Regards Frank

[Pegasus_1]

If anyone is interested I have a as new Permatrim for sale to suit a larger outboard (60hp and above). It is for sale in the classified section under electronics and chandlery


Many thanks


Pegasus

[John Buoy]

Hi all
I have added an email sent to Markham Marine with findings on Permatrims added to my 4900 Dominator
And a pic i thought i would share with you all
Regards Frank...

Hi gavin
i have fitted twin 96 ltre fuel tanks above floor under the seat boxes(original long type)
and i was concerned with the extra weight shift forward when full.
Consequently the extra weight gave my boat a softer ride but with only twin honda 50's
getting up on the plane took a little more push.

After some hefty thinking re foils on cats and how they would affect my rig
I spoke to a couple boating gurus in the states and they recomended fitting the Permatrims.
Having been involved with all types of cats for most of life i was still sceptical
about the bury and dig associated with foils but saw the Permatrims as an extension
of the cav plate due to the design and after some serious thought i decided to accept
the Permatrim challenge and fitted the approriate type suited to the Honda 50's.

Drilling holes in my Cav plate was not a god feeling but after touch up paint and a bit of clear
all is well and looked the goods.

Testing day arrived boat was already filled from previous trip and also asked a mate
that fishes with me on occasions to join me for the test as i needed his weight onboard
to have some conclusion to the test.(he is 98kgs).
Boat is now loaded and on a Port Phillip Bay 15 knot chop conditions were ideal for testing
Prior to the fuel tank modifications in these conditions the rig would plane as normal and text book landinds in some of the bigger waves typical of the dominator landing ass end first and fully safe.
Now with an extra 150-200kg of weight moved forward and central and with the trims in normal position slightly
nose up the first reaction and planing speeed left me absolutely stoked and gleaming with satisfaction
and after a few adjustments to trim heights i was left with no doubt that the Permatrims was a great addition
to the Hondas and Dominators perfrmance.

None of the original charecteristics were lost and with less fuss and spray around the engines.
Prior to the trims being fitted and in calm conditions porpoising was a slight problem if the weight wasn't
distrubetd properly or a hefty amount of negative trim added.
Now i find nil porpoising in any trim position less transom drag with the hull siting slightly higher heaps
more positive and negative trim available and no top end speed loss even with the extra weight!!.

I have no association with Permatrim and was a sceptic on cats fitted with em but if you have customers
in my position with Honda 50's on a 4900 now (5500) I would have no hesitation in advising the Permatrims
on this model and in fact i can say that they feel as if they were a part of the this particalr models design.

Hope you can use this info to satisfy the ever growing band of Markham Dominator fans such as myself.
p.s i have added some pics for you.

Regards Frank.

http://img9.imageshack.us/img9/7042/permatrims002.jpg (http://img9.imageshack.us/my.php?image=permatrims002.jpg)