Mainship Trim Tabs

I have a 97 Mainship 350 and my Trim tabs will not extend fully. My zinc diver thinks they may need hydralic fluid, but my mechanic looked everywhere for the pump where he could fill the fluid but could not find it. Anybody know where the pump/s are? Thank you.

On my 98' 350 the pump is on the shelf aft of the starboard rudder. Mainship did determine that the trim tabs have absolutely no appreciable effect on the attitude of the boat. In others words, retract them all the way up and forget about them. They. Are. Worthless. Some owners have remove and glassed over them.

Push the buttons and listen for the pump.

Bob

Chrises Craft said:

I have a 97 Mainship 350 and my Trim tabs will not extend fully. My zinc diver thinks they may need hydralic fluid, but my mechanic looked everywhere for the pump where he could fill the fluid but could not find it. Anybody know where the pump/s are? Thank you.

Click to expand...

They are probably electric. The tabs on our '97 350 are Lenco electric tabs. If your controls for them have Lenco stampet on them, yours are the same. No fluid. I wouldn't worry much about them, they are pretty useless on this boat.

Just a comment from a SOB [some other boat]. I have trim tabs on mine and at first glance I thought they would be useless. Slow boat and although planing hull. underpowered to do that so I figured useless.

After a while I realized I was too quick to write them off. They do help with correcting a list while running and they definitely help knock down the big rolling following wave when I push the boat a bit. The wave size change is quite visible.
I can also hear a ever so slight unloading of the engine as I put the tabs down from fully retracted.

I cannot determine if they help with fuel economy. I suspect they do but the correction would be too small to find without some esoteric equipment I don't have.

But from some observations they make a difference in the boats operation.

Yours truly may be useless as others, with similar boats, say but maybe not quite as useless especially if you are running close to hull speed and not trying to plane.

The Mainship 350/390 is different from most other boats in that the swim platform is actually an extension of the hull. Mainship embedded the tabs in this extension, not outboard of it as most boats have the tabs. In essence, the extension is one massive trim tab. The tabs on this boat really are useless, and the screws attaching the tabs tend to leak after time and allow water to fill up in the extension, which is the main reason some owners have removed them and glasssed the area over. On my list to do someday!

Thanks everyone for your helpful replies.