Trim tabs on a rib?

[thorsby]

I have a chasecraft 650 running a Suzuki df140. It's a bit slow onto the plane and carrys quite a bit of weight aft. I've seen these "automatic" trim tabs around and am wondering wether anybody had any experience on them and wether they're worth fitting?

[Jus]

Originally Posted by thorsby

I have a chasecraft 650 running a Suzuki df140. It's a bit slow onto the plane and carrys quite a bit of weight aft. I've seen these "automatic" trim tabs around and am wondering wether anybody had any experience on them and wether they're worth fitting?

Yes, I have used these on a 5 metre RIB.
The boat was rear heavy as it had a 100hp on and tended to bog down quite a bit, and also come on and off the plane trying to tow skiers at a sensible speed.
I fitted the tabs and it did make a difference. It definitely planed more quickly and planed down to a lower speed. It didn't seem to have any negative effects like I have experienced with outboard based fins.

[Oldun]

What were the negative effects you encountered with the outboard based fins. I was concidering fitting them myself. Oldun.

[Jus]

Originally Posted by Oldun

What were the negative effects you encountered with the outboard based fins. I was concidering fitting them myself. Oldun.

I'll say first of all that it was not a RIB, but a an open GRP sports boat that I used them on. The trouble I has was that when turning at speed, the bow of the boat would really, really dig in hard. For this particular hull, it would sometimes cause the boat to then heel hard in the opposite direction to the turn. This was particularly noticeable with a following sea, under which conditions it felt actually pretty dangerous.

I'm not saying it was all down to the fin, it could have been the combination of it with that hull, but it definitely didn't work well!