Trim Tab installation

ghcpa9 said:

Looking to install trim tabs on my 208 after I pull her out of the water this fall. 2 questions, has anyone here noticed a major difference after installation in terms of keeping the bow down? I can trim the motor all the way down plus I have doel fins installed (came with the boat) but the bow still a bit too high for my wife's standards. I tend to agree.

Also, what do you have to look out for in terms of not drilling into the wood in the transom? Or can it not be avoided and there is a safe way to do it? Just want to avoid a problem with the wood later on.

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I'm surprised to hear you run bow-high. Do you have a photo compare to my sig-pic? I only run one tab down to correct for prop torque, and trim the motor all the way out for high speed running. If there's a chop, I may trim it down a bit, but if you bow-down too much then she's pushing the bow in and all kinds of crazy handling shows up.

When you mount your tabs, just seal everything with 4200/5200 sealant. Same for the hydraulic lines, they come out under where the top of the rams mount. Leave your lines all the same length so they work the same when you run both switches.

If you have any questions contact Todd Bennett, he's extremely helpfull and happy to help any way he can. He also hosts a forum section on THT.

Hi ghcpa,

We've got the same boat and motor, just 2 years removed. When we installed tabs on our 208, we sealed the holes through the transom for the actuator tubes with West System epoxy. I think the WS is better than the 5200 since it will wick into the wood and create a better seal than the 5200 will. We also used the WS on the screw holes below the waterline by first dry installing the screws, then removing the screws, injecting the WS into the holes with a syringe and reinstalling the screws. We did use 5200 to seal the screws that hold the top of the actuator ram.

Be extra careful when choosing the location of the tabs for drilling the holes for the hydraulic lines to make sure you're clear of everything mounted on the inside of the transom. We measured things probably a dozen times before drilling, since we only had about 0.5 inches of clearance from the main 40 amp circuit breaker on the starboard side. The port side we had to maneuver between the washdown pump and fuel filter.

Other than that, it was a 4 or 5 hour project for 2 people who'd never installed tabs before. We took our time to make sure everything was perfect and sealed up well. It was actually quite simple. Good luck! You'll really like the tabs. Our 208 rides much better with them as the bow never pops up at all, even when the tabs are fully retracted. Before the tabs, we would occasionally get into a rhythmic porpoising or bouncing motion that would require a course change or throttle adjustment to stop.

This photo may help you find a good location to install.

When you drill the holes thru the glass, you need to bevel the outer opening with a larger bit run in reverse so as to avoid cracking the glass which can allow water to migrate thru the crack as the crack probagates, it will, all cracks do eventually.

There are bits made for this but be sure not to overdo the bevel, so go slow.

This goes for any hole you drill into glass that uses screws to bear down, not so for bolts with theaded nuts.

Don't be chinzy on caulk, caulk the thread and opening, and full face of the flange, clean surfaces and screws with denatured alcohol to be grease/oil free. I prefer Boatlife Life Caulk for this application. Life Seal and Life Caulk is all I ever need, below or above waterline. Life Caulk is not for plastics, Life Seal is.

Once it cures, never turn the screws again nor ever check if it is tight by torqing the screws. You don't have to.
If you do by mistake, remove screw all the way, clean, and recaulk all over again.

Ono, good job on the install......I agree with all.....epoxy first for the wood, then plenty of 42,52 or Lifeseal and a good pre clean with solvent. Use the proper size drill for the screw as well.....if the wood is a little damp, use a heat gun with a small copper tip and dry out the hole a bit...use low heat and watch what your doing to avoid overheating the gelcoat......thats it.....As good as it gets.

As far as sealing thre hull, always use west systems epoxy to seal the exposed wood once drilled, then fill with 4200/5200, I would personally use 5200 below the water line but either works. Thru bolting would work best and allow the transom to stay sealed properly, crews might work but can and likely will pull out over time, and will make that water tight seal not so water tight down the road. Do the job right, do it once and never look back having to worry about will it last.

Ditch the Doelfin. It was a band-aid ... :wink: