Trim tabs? Should I?

[Nslfishing]

Hi all
just wanted to ask advice on getting trim tabs installed on my 5.1m aluminium cuddy. Is this boat too small for them, are they dangerous in any way, could I install them myself/should I?(pretty handy on the tools). Any advice would be greatly appreciated thanx in advance Nic

[stue2]

never seen or heard of a boat disadvantaged by tabs

[cormorant]

Nic - What are you trying to solve with trim tabs? Why do you think you need them?

What boat and motor do you have and does the motor have any fins fitted to the cav ( anti-airation ) plate above the prop?

A lot of issues can be partially solved at very little cost with better motor, weight distribution and prop set up. Some issues with motor weight and hull design can't.

Tabs are good but come at a price to your wallet and seriously boats went out for 50 years without them by moving weight about and changing the way we traveled with the prevailing water conditions. Some boats need em and some boats can do without them depending on the habits of the boat and what it is being used for.

[Malcolm W]

Most find them a positive, tried them on my 5.6 ali that tended to lean to port, especially with the wind on that side and ended up taking them off. I found by trying to even up the hull it tended to push the nose too deep, slow down and use more fuel. I tried every position possible and it appears my hull is a little nose heavy. My dive tanks go at the back and to one side to fix this.

I now just distribute the load better (eskies and people) to compensate. If your not fussed doing this it's far cheaper. They seem to be popular on bigger, heavy bum boats.

Many on here love them and wouldn't be without them. Personally I feel a 5m ali boat is not difficult to alter the load without them.

[Nslfishing]

I notice especially into the wind and with a breeze from the starboard it leans to port quite a bit. tried distributing weight but still has quite an uncomfortable lean. It's a 5.1m 4 seasons windstorm (I know ;) ) with an 05 90hp yamaha. Being not the largest of boats I'd like to keep the back clear of clutter eg Jerry cans and such as counter weights also don't really want to be stuffing around balancing things out every time I go out. The only fin thing is the one that hangs down from the cav plate.

[cormorant]

If it doesn't lean on flat water with no wind and small amounts of weight moving on a windy day won't fix it you could use tabs but most I see are huge for that size boat and not cheap. I don't know first hand that hull but sometimes trimming teh motor differently will work a different section of the hull and make a difference to just how much lean you get.

If that boat doesn't track well and stay flat on flat water in both directions I would be having a very close look to see if the hull is still straight and true. Is it consistent lean to one side ? Asking as motor may not be mounted vertical or in middle of the hull? Hull may not be square out of the jig or welds gone causing flexing - just asking?::):-X Does it happen at all speeds and all trim angles?

The small trim tab behind the prop is to stop torque from the prop induced steering . Ie let the steering go and it still should steer straight and not have much pressure on steering gear. It can affect lean a small amount if not correctly set.
Not sure what prop you have but may be worth a chat with someone about the prop as some cause a lot more lean than others at different speeds. Small weight moved to the side at the front or rear can make a big difference so try you options again before spending the dosh
The permotrim style cav plate additions or wings was what I was asking about ( had brain fade and couldn't remember name) as some with the motor set too low drag and cause weird handling. Check when under way just what height your cav plate is out of the water and put in some tight turns to see if the prop breaks out.

Lastly get a fat mate and keep him on a exercise program of trimming the boat ha ha !!

Comes down to just how long a runs you do and how wet the passengers get or how uncomfortable it feel as to whether you dip you hand in the deep pocket. Check if there is good access , room to actually fit them and if other things need to be moved otherwise it starts to get expensive.

[Nslfishing]

Hmmmm. Given me much to think about I will experiment a bit more before making the decision. Usually it's me an my 11 yr old son who lacks the bulk to act as a decent counterweight haha. I've had it in the river in glassed out conditions and she ran straight as an arrow but still had a small lean to port. Most of may fishing is done around moreton and I want to start fishing offshore but was a little concerned cause I don't want to get out there and spend the whole journey feeling like I'm about to roll lol. Thanks heaps for your time cormorant really appreciate it Nic

[Malcolm W]

I tried everthing to stop the lean to port. Had an engineer look at the hull, lifted the motor and tried moving it as much as the play in the bolts would allow. Tried the little trim tab as well. It stays flat in the water until it gets up in speed (12-15 knts)

Came to the conclusion it's just prop torque with a deeper than average deadrise. The 4 blade prop probably adds to the torque. It has a very deep v at the transom with large chines at the outside.

[honda900]

never seen or heard of a boat disadvantaged by tabs

stue2,

Drag and efficiency are effected.

http://www.ausfish.com.au/vforum/showthread.php?184011-Trim-Tabs-and-fuel-economy&daysprune=365

Regards
Honda.

[Schulzy]

9x9s should be ok for it

[Nslfishing]

cheers for the info there Honda. i had a read of that thread. Now i'm wondering how much they will affect fuel efficiency as well, something i hadn't really considered.

[stue2]

stue2,

Drag and efficiency are effected.

http://www.ausfish.com.au/vforum/showthread.php?184011-Trim-Tabs-and-fuel-economy&daysprune=365

Regards
Honda.

Yep agreed. but the upside is better ride and comfort(generally) Even with twins as I have, a boat can be trimmed more efficiently with tabs..

cheers Stu

[Chimo]

If your looking for benefits with minimum drag etc fit 9 by 9 Lencos or similar as Schulzy said. This type will be the go you will get more drag with the drop down type as tested and reported by Peter Webster when he fitted them to a tinny he had. Lost one kn off the top speed but still worth it.

Cheers
Chimo

[Nslfishing]

What about fitting guys? Should I get a professional to fit them. Do they have to be mounted according to hull shape and design or can you just bolt em on the back and away you go? I'm guessing you want them level with the bottom of the hull or slightly higher.

[Floating Rib]

Hi , i have a 6.2m rib and have fitted the Nauticus Smart Tabs, i think they are fantastic, cheap, fit yourself and you can use a mounting bracket that allows you to deploy them when you have a load or not, personally i leave them down all the time. No electronics involved but they are easily adjustable to suit the amount of lift you require, plenty of info on their website. I bought mine in from the states but they are available locally now.
Cheers
Mick

[stue2]

What about fitting guys? Should I get a professional to fit them. Do they have to be mounted according to hull shape and design or can you just bolt em on the back and away you go? I'm guessing you want them level with the bottom of the hull or slightly higher.

If your a bit handy you will manage. They come with fitting instructions and everything else is on youtube. If you are a little bit unsure then get a pro to do it. Look into how to attach them on a tinny.

cheers Stu

[Tickleish]

Tabs are good but on a boat your size I would say it has more to do with weight distribution.

It does sound a bit strange as boats normally lean into the wind not away from it. I noticed your in Cleveland, we'll be going out on Sunday for a run. If you want a second opinion I would be happy to go for a run .

[Cav(J.C.)]

Hi,
Something that may cause a list when planning is the transducer, especially if transom mounted. if your list is the opposite side to the transducer, then a permanent trim tab ---one only will get you out of trouble.
email me---ddg38@bigpond.net.au I will be able to send you a photo of a cheap adjustable trim tab in aluminium which I built for this purpose.
Cav(J.C.)

[Greg P]

If your looking for benefits with minimum drag etc fit 9 by 9 Lencos or similar as Schulzy said. This type will be the go you will get more drag with the drop down type as tested and reported by Peter Webster when he fitted them to a tinny he had. Lost one kn off the top speed but still worth it.

Cheers
Chimo

Why do you keep bagging the QLs with no first hand experience. They don't create any drag when retracted so if his were causing that they weren't installed correctly or had an mechanical issue where they weren't retracting fully. I have had mine on for 6 years now and love them - had bennets on my previous boat and they were great as well.

95782

Here is an article from Mr Webster testing Bennets on an old Pacific Sportfish and as you can read any tab (Bennets, Lenco or QLs) fitted when in use is going to reduce your speed and increase fuel consumption in flat conditions at a given RPM - no getting away from that, the more drag from the tab and more hull in the water means more friction. They fuel savings only come in crap conditions were you can keep the boat on the plane easier and can adjust your engine's trim to best efficiency (you can hear the sweet spot after a while but even more so with a fuel meter) as opposed to no tabs and trimming the engine in to keep the bow down and the boat up on the plane- thats all.

[Nslfishing]

I recently installed a new transducer and have it lower than the hull cause I kept losing the bottom while on the plane, it's possible that its playing a part in this problem as well

[Cav(J.C.)]

Hi Nslfishing,
I think you've hit the answer. If you've installed the transducer with a slight downward tilt so that you do not get bubbles over the face, you have in fact installed a trim-tab which at speed will give you a list. The correct way to fix this is to fit a tab on the other side to compensate.
I have been through exactly the same process.
can send you photos and specs of the fix.
Ph 0755772872 0r email ddg38@bigpond.net.au
Sorry--I don't know how to send pictures on this site.
Cav(J.C.)

[johncar]

I have been taking my 5 metre CC ally boat out to sea a bit and have Bennett 9" x 9" M80 tabs fitted myself. I believe that all boats with a single standard rotation prop will have some tendency to lean to port as a natural reaction to the props rotation. It has been my experience with every boat I have ever owned anyway. This boat I have the batteries, engine control, fuel and wiring on the starboard side and the transom mount sonar transducer on the port side to help counteract this and it does pretty much.
Wind, currents, waves, speed, transducers, big deckies and loads all have an impact on a boats trim as well.
Depending on your boating habits, and where you intend to go, it may no be so useful to have tabs, but for me as I head out of Pumicestone Passage, across the bay, around the top of Moreton Island and head either north or south from the Cape I would tweak the tabs several times to keep the boats nicely trimmed and optimum for ride, safety, economy, comfort and dryness, so I can't really contemplate owning a boat for my purposes without them.
Tabs do work better with boats that are either well balanced or tending bum heavy so you should try and achieve that first.

A bow heavy boat can be nasty offshore in a decent following sea and tabs may make this worse if engaged at the wrong time and even with a well balanced boat I would use tabs very sparingly if at all in that situation.

Have QL's on the 6.6 metre boat and they too do an excellent job and wouldn't fancy going to sea without them.

Pic of the M80's fitted. Out a little wider would be better but limitations with the transom design dictated where they went. They work very well.

95787

[thylacene]

I fitted a set of 12w x 9l lenco edge mounts to our 6.3 Caribbean Reef Runner, which is a bit bum heavy, and can only speak highly of them, except that in hindsight I shoudl have fitted at least 12 x 12 as I I often find myself using "all" a of them without the nose digging in too much. Additional width has less effect than additional length in tab sizes.

With respect to your question, the capability to level your boat is limited to certain conditions. In any following sea, you should keep them fully up to avoid the nose digging in, and the extra "lift" causing your hull to broach. I experimented to find out, it can be quite unsafe, so small step experiments.

Where I find the real advantage is into any oncoming sea/swell. Adjusted correctly the tabs stop the bow from "launching" off the swell, resulting in it falling a lesser distance, reducing the impact on the hull and the passengers dramatically. In any head on to quarter sea they really deliver.

Our previous hull was a 540 Quintrex Millenium Bowrider, and I feel that it would have benefited from a set of tabs.

I would be wary of using the Smart Tabs, unless you have some way of retracting them when you have a following sea.

If you choose to proceed, I would recommend that you consider carefully the size you choose. Our Lencos are easy to adjust in small increments, so slightly larger and under utilised is better than not enough.

Ease of fitting is something that needs to be considered, important questions are;

Is there room on the transom on both sides, moving stuff involves additional repairs?
Is the surface straight or curved that the tabs will fit up to? If curved, you can make a nylon spacer shaped to provide a flat surface, but it is more work.
As your hull is alloy, you might want to try and hunt up a set of alloy tabs, or be prepared to put a space between steel tabs and the alloy hull.
Do you have access to the inside of the transom where the bolts will come through? The kit turned up with stainless self tappers an inch long and 1/4 inch. Possibly not the desired mounting for alloy, so being able to reach nuts inside the transom could be important to you. Alternatively you could use blind rivets, and fill the heads with Sikaflex to avoid water reacting with the steel head left inside it.

The actuators on the tabs come well up the transom, about 14 inches from memory, so is there any obstruction such as a fuel filter or other item. I had to compromise slightly to avoid moving a transom mounted deckwash.

Wiring is extremely simple on the Lencos, it is all plugs and play, with three connections required, a switched positive, a positive, and a negative. The switched positive should come from a feed that is only live when the key is on, as it actuated the auto retract feature.

Have not used Bennett's or Minn Kota so I cannot compare. To be honest, the Lencos were the easy fit option out of the three. I recently fitted a set of 12x12 to a mates boat, and it took me about six hours all up, not rushing it, measure twice, drill once. Having an extra set of hands around is a good thing. Have not had a chance to test it yet, the weather gods are growing on us.

Hopefully someone who has fitted tabs to a similar size boat can give you a better indication of how they behave on a similar hull to yours.

Hope this helps your considerations.

Cheers

Thy

[Andrew Wylie]

Hi Nilfishing,
Did u end up putting the trim tabs on, or come up with an other idea or not, and if u did put the trim tabs on, how have u found them, in varying conditions so far ?
As l am looking to install trim tabs my self any feed back would be great, thanks.
Regards
Wheels

[Nslfishing]

Still haven't purchased them yet but they're definatly on the list. Stay tuned ;)

[Andrew Wylie]

Hi,
Have you any ideas which you may be fitting the electric or the auto one Nauticus SX type ?

Cheers
Wheels.

[Nslfishing]

I'm thinking the 12x12 lenco or Bennett's. Most of the reaserch I've done says bigger is better (in length). As thylacene says, and I'd agree, you don't want to be using "all" of them if you don't have to. Disclaimer: Keep in mind I've never used trim tabs before :) . Not sure if I should go electric or hydraulic though, I'll probably go electric (less maintenance I Spose and less stuff to install ie reservoir and stuff)

[stue2]

I think you would be better off with the smaller 9x9 size. Less chance of line hitting them and you boat is not that heavy so will respond very well to smaller tabs.

cheers
stu

[matt mill]

hey mate

Have you seen the new Bennett Self Levelling tabs?

http://www.bennetttrimtabs.com/catalog.php?vID=274&catHome=1

Easy install and only about $250 for the 10"

Cheers

Matt

[Nslfishing]

I had a look at them a while ago. My questions are can you override the self leveling function and work them manually if you want/need to. And how smart are they (would they adjust themselves say when your in a following sea and put you into strife?

[Lancair]

IMHO There's so many mistaken ideas idea's about trim tabs and their correct use in this thread. A few people have the right idea with prop torque being a MAJOR culprit in causing a hull to lean, esp. to port.

The little trim tab on the underside of the anti ventilation plate plays a MAJOR role in getting your boat to perform best. If it's not set right, everything else is out and Trim Tabs are a band aid solution.

Before you start messing with the trim tab on the AV plate, make sure your boat floats perfectly level when normally loaded with fuel etc. and no one on board.
Basically the trim tab needs to be set, so that at WOT running speed with the motor trimmed to max rpm without venting (no cavitation as its commonly termed), you should feel no bias in the steering force to turn either way. Best tested and set in nill or very light wind situations. At this point the motor is at its most efficient. Anywhere from this point trimming up, you would hear ventilation. Trimming down, will bring the bow down, decrease in RPM and speed, an increase in force req'd to hold the steering straight in a tiller steer or an increase in force to turn to port and easier to turn to starboard in hydraulic steering, older cable etc. types should be easier to feel. With hydraulic steering it can be hard but not impossible to feel the torque. You will also notice the port side lowering as you increase down trim and hold a straight line. This is the prop torque. Once we have that sorted you'll that evenly loaded in light winds the boat will run true.
Once the AV trim tab is set at WOT, you'll be able to find the sweet spot at ANY speed.

Wind from the side of a boat tries to push the boat sideways, the rear end is pretty well fixed to its track in the water by the motor leg, so the bow moves easier. As wind pushes on the starboard side, the bow moves to port, so you turn more to stb. to counter that, effectively your boat is now in a slight stb. turn. What happens in a mono hull when you turn stb.? It rolls to stb. as well. Why? Because the prop not only turns the boats bow by changing the thrust line, but that thrust line to the stb. is below the centre of gravity of the boat, so it pushes it over or rolls to the starboard.

Here's where Trim Tabs like Bennets or Lencos etc. come into play.
When the boat is rolling into wind, its not cutting the water as the hull was designed to do, it's partially bashing a much shallower angled hull side making the ride uncomfortable and not very efficient. Use trim tabs to level the hull.
When pushing into chop or a sea, it's often more comfortable to have more of the front of the hull working, cutting the slop and smoothing the ride. As we saw, trimming down or in will lower the nose and smooth the ride, at the expense of a roll due to prop torque. Use the Trim Tabs to lower the bow but leave the engine trimmed at its most efficient spot.
As mentioned already, in a following sea you want Trim Tabs up and the motor trimmed at its most efficient spot for the speed, keeping the bow higher.
Of course trim tabs can also even up a poorly loaded boat, but at the expense of fuel consumption.

I hope this helps someone. I learnt so much from my first PTT equipped tinny.

[Volvo]

[QUOTE=Lancair;1514111]IMHO There's so many mistaken ideas idea's about trim tabs and their correct use in this thread. A few people have the right idea with prop torque being a MAJOR culprit in causing a hull to lean, esp. to port.

The little trim tab on the underside of the anti ventilation plate plays a MAJOR role in getting your boat to perform best. If it's not set right, everything else is out and Trim Tabs are a band aid solution.

Whats the chances of explaining how you adjust the little trim tab below the anti ventilation plate:)????.

[Vitamin Sea]

IMO 12 x 12's would be a vast overkill NLfiishing, simply not required. As has been suggested 9x9 's will more than do the job on that boat.

Trim tabs are great for correcting wind list and improving ride quality. I had 450mm QL tabs on the 19c haines i had, best money i ever spent on it. For the improved ride they cost me 1km/hr and .1 L/km., not worth considering.

cheers

VS

[Volvo]

Well I have a slight dilema with my trim tabs hence the quote. I do have the Lenco 12 x 9 and with a stiff breeze outside comming in from the starboard side I get a good list to that side.
In flat smooth waters the trim tab down on that side corrects the problemo fully but outside it only halfe corrects the problem and my rig is a 6 mtr platey.
So seems i have two options that i can think of, go 12 x12 plates or spacer under the rams give more surface area downwards to give more bum up lift??.
Though that would also effect the amount of plate out of the water when not using the tabs which from previouse threads would effect the boats performance in a following sea ??.
Having also read and viewed instalation guides to fitting trim tabs its been stated that 5/8ths inch plate clearance from hull level is ample ??.
Previousely had a 130HP evinrude with three bladedprop whereas now I have a 150HP Honda with four blade prop, hence more tourque n maybe why now more starboard list ??..
Also to make room for my trim tabs i had to have removed from the starboard side a small plate with a water pickup for live bait tank and think that may have acted as a small tab in itself , hence less list previousely..
So question is, which way to go ???.

[odes20]

So if your tabs are not mounted specs you should fix that first IMO. Your tabs are big enough. I only have 9x 9 on my 6 metre fiberglass and they have a tremendous impact.
It would be way easy to trial a spacer as you suggested .

[Chimo]

I too have 9 by 9 Lencos on a 6.2 Vag and they are plenty and are as recommended by Seafarer's Lindsay Fry.

Who fitted yours? Are they experienced in this task?

Given the issues your experiencing why would you not obtain input from a qualified, experience tradesman? How would you fix a broken heart?

Wonder if there's a chat-site for budding heart surgeons etc although I know they do go to M & G sessions (conferences) in places like Los Vegas etc which is a bit like Sth Stradbroke Island without the pokies

Cheers
Chimo

[Volvo]

I too have 9 by 9 Lencos on a 6.2 Vag and they are plenty and are as recommended by Seafarer's Lindsay Fry.

Who fitted yours? Are they experienced in this task?

Given the issues your experiencing why would you not obtain input from a qualified, experience tradesman? How would you fix a broken heart?

Wonder if there's a chat-site for budding heart surgeons etc although I know they do go to M & G sessions (conferences) in places like Los Vegas etc which is a bit like Sth Stradbroke Island without the pokies

Cheers
Chimo

Yep, just had another squizz at the pics you uploaded as well as did find some Forums regarding trim tabs and instalation and mine have been fitted outa kilta from recomended fittting instructions so as not to have to weld holes and redrill newies it appears the spacers will have to do the job.

[odes20]

good call Volvo. you will gain the travel and influence. Have the outer edge raised no more than 10 mm

[Andrew Wylie]

Hi Nilfishing,
just wondering how far you have progressed with your trim tabs ?

Regards
Wheelybin.

[Nslfishing]

There still on the list. Hydraulic steering first 😃.