Does anyone know anything about Gibson manually operated hydraulic trim tabs? I have them on a boat & am trying to get my head around how they operate. they pump down OK but seem to come up again as soon as I stop pumping? I am sure there is nothing wrong with them & that it's 'finger trouble' but any idea's would be appreciated. :thanks:

Shouldn't they just move with the lever? Could there be air in the system, of maybe soft pipes?

Think you are right Rod, fully fwd for fully down it looks like. Simple - I was over complicating it (partly based on what I had been told).

When would I expect to use them - apart from leveling the boat I running single handed (side by side seating)??

You'd be likely to use them to get out of the hole quicker, in lieu of trimming the motor, also to level up if loaded off-centre or in a crosswind, and of course to adjust the attitude of the boat (ie, bow up or down) for max speed in flat conditions, or safer running in choppy conditions.

They would do much the same thing as power trim on the motor.

They would do much the same thing as power trim on the motor

Which the motor has?? I guess I would use them for trimming her level then.

Thanks Twister.

PS I want your honest opinion of this one when you get the chance to give her a run.

Yes please!!!! :thanks:

The boat explains the 'almost static' trim tabs - very deep vee, therefore prone to running on one chine in a seaway, specially if ski racing.

Ahh right. Makes sense now, she is built as a ski racer same as Phil's 'Tarantula'. Thanks Rod. :thanks:

we had tabs on our first three boats and I had good and bad experiences. (the first boat being our 1st ever boat and was very green !)

1) Make sure they are both flaps down before coming out the plane (or both up but they are not helping then). If they are slightly different you will pop up out the hole and suddenly heel over onto one rubbing strake..hahaha did this at about 25 knots in a sealine 19 in the early days mid solent and fought like hell to put her back. Was hanging onto the helm for grim death and could not let go to fiddle with the little switches (bennet hydraulinc ones) and she was very very tippy as yours will be. Lynn was kissing the water on her side and am sure will tell you all about it

2) Once out the hole trim the nose using both flaps equally to suit sea conditions, nose up a bit more in a chop of course and on a flat you can nose down more to get better speed by being more on the water. That deep V like an old sunseeker of ours will give a soft landing as you fly of the waves.

3) Yes you can trim the level (port starboard) and this is of use with either an uneven load or more i found in a seaway. wind and tide could cause a surprising heel over by some degrees and turning round to run back the other way on a long run meant trimming the flaps the other way.

I think you will find the tabs quicker to react and in many ways better than the engine trim. We had this on the OMC inboard/leg but it was slow and frankly we tended to just set it and fine tune on the tabs.

Hello there
I have recently purchased a second hand pair of Gibson trim tabs before fitting to them my boat I was wondering what the travel of the rams should be ; from what I can tell it appears to be only 20mm does this seem right ;


cheers Dave

I will have a look at mine over the weekend, I don't think they move far, but don't need to if mounted closed into the hull (tab end).

Anyone know where to get spares for these? One of the rams on my boat leaks.