Let's Talk Trim Tabs

[Flat Broke]

We took the Scarab out this weekend, and for the most part had a great time. A couple little issues, but for a first time out with the kids a new-to-us setup, I'm pretty happy with the hull in cruddy water.

The one area that needs some work is planing out at slower sped for tubing, and controlling the boat's tendency to roll in uneven water at moderate speeds. I know tabs will help keep the bow down, but how effective are they at combating rolling when mounted parallel to the bottom of the hull?

Would I be better off mounting them horizontal to stabilize the side to side rolling? And if so, how much longer would they have to be than tabs mounted parallel to the bottom to hold the bow down when planing at low speeds or with heavy loads? How do you determine where to mount them when mounting them horizontally?

 

[hallett21]

We took the Scarab out this weekend, and for the most part had a great time. A couple little issues, but for a first time out with the kids a new-to-us setup, I'm pretty happy with the hull in cruddy water.

The one area that needs some work is planing out at slower sped for tubing, and controlling the boat's tendency to roll in uneven water at moderate speeds. I know tabs will help keep the bow down, but how effective are they at combating rolling when mounted parallel to the bottom of the hull?

Would I be better off mounting them horizontal to stabilize the side to side rolling? And if so, how much longer would they have to be than tabs mounted parallel to the bottom to hold the bow down when planing at low speeds or with heavy loads? How do you determine where to mount them when mounting them horizontally?

what length is your boat? Tabs will help push the nose down at lower speeds as well as control the boat's tendency to lean left or right. Boat length will play a factor in how you mount them.

 

[Flat Broke]

The boat is a 22'er. Most stuff I've seen in this size range with the exception of high hp ski race setups have the tabs mounted parallel to the bottom; but I've seen pics of a few Warlock 23s with horizontal mounted tabs. That got me to thinking about which etup would be better for my application.

 

[Blazen Js]

I have a hull similar to the 23 Warlock and mine are parallel to the hulls bottom. They work very well and well worth the $. :thumbsup

 

[BLOWN HOWARD]

Mine is a 22 and mounted like this work bitchen

 

[NoDoz]

Not to hijack the thread but maybe this might throw some added info out to Flat Broke...
My tabs are mounted in line with the transom (not flat) and my boat tends to chine walk at about 70-75 even in fairly smooth water. I trim my drive up but never really touch my trim tabs. Where should my tabs be? and I actually don't have a trim tab indicator, is that uncommon? I have dana trim tabs, where can I buy an indicator? Thx.

 

[hallett21]

Not to hijack the thread but maybe this might throw some added info out to Flat Broke...
My tabs are mounted in line with the transom (not flat) and my boat tends to chine walk at about 70-75 even in fairly smooth water. I trim my drive up but never really touch my trim tabs. Where should my tabs be? and I actually don't have a trim tab indicator, is that uncommon? I have dana trim tabs, where can I buy an indicator? Thx.

i'd instal the indicator so that you know where to automatically adjust so that you can just set them and run. After a while you'll get used to where the tabs need to be on the gauge at different speeds. I would think that pushing the tabs down a bit on both sides would get rid of the chine walk. You can still trim out to get the lower unit out of the water and reduce drag.

 

[hallett21]

The boat is a 22'er. Most stuff I've seen in this size range with the exception of high hp ski race setups have the tabs mounted parallel to the bottom; but I've seen pics of a few Warlock 23s with horizontal mounted tabs. That got me to thinking about which etup would be better for my application.

I think that the length of the tab dictates if they are mounted parallel or not. On our hallett vector (21ft) we have bennett tabs that are like 12" x 12" so they are parallel to the hull. But it seems that the longer tabs like the mercury and dana ones would need to be mounted horizontal because they have a lot more surface area that would cause I a lot more push on the nose, even with the slightest adjustments.

 

[Flat Broke]

At least we're getting some good discussion on the subject. I agree that the longer planes would be sketchy mounted parallel to the bottom on a small boat as you'd have waaaaaaaay more leverage than needed and could drastically stuff the nose with minimal movement. I'm looking at doing 1 of 2 things. If the concensus is the run parallel to the bottom, I'd get a set of pre-fab sport tabs in the 12-14" range likely Lenco actuated. If it seems like horizontal tabs would be best, I'll buy Lenco actuators/switch/indicators, and machine my own planes to get the length and shape I want when installed at the appropriate area of the transom based upon pictures of the transom with the boat running on plane.

My thought is that a long tab mounted inboard horizontally will do a good job controling chine walk when running on the pad because they won't have to drop too far to dab and create stability. The obvious downside is that the tab would have to be extremely long in order to generate enough articulation to force the nose down hard for tubing etc. Conversely, parallel tabs mounted more outward would be great at slow to moderate speeds but would require a lot of articulation to hit water when the boat is riding dry.

Maybe some of the ski race guys can chime in with their experience, though their speeds and power may skew recommendations somewhat compared to my realatively slow setup.

 

[hallett21]

I've seen a couple hallett 210's with two sets on tabs. Maybe you could venture down that road.

 

[NoDoz]

i'd instal the indicator so that you know where to automatically adjust so that you can just set them and run. After a while you'll get used to where the tabs need to be on the gauge at different speeds. I would think that pushing the tabs down a bit on both sides would get rid of the chine walk. You can still trim out to get the lower unit out of the water and reduce drag.

Cool, Thx. I hate when I push it a little faster when I get to smooth water and then I got to pull off a little bit because I get a little walk. Not bad at all, I'm just apprehensive because I see all those crash videos