Larger trim tabs will help the boat to stay on plane at lower speeds but
they will create more drag which will defeat the purpose. For best fuel
economy - you need to use minimal tabs (just enough to keep the boat level)
and use enough throttle to keep the boat on plane. Throttle gives you more
speed. Tabs create less speed due to drag. Speed vs throttle setting is
what controls fuel economy. The more speed you have for a given throttle
setting the better fuel economy you will have. W/ tabs buried to stay on
plane you are creating a lot of drag and load on the engine. This really
reduces economy.
At least that is my (and several friends) experience w/ larger boats.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com
"Big Daddy" wrote in message
m...
Hello. I have a 29' Chaparral (great boat) with twin v-6's and Volvo
duoprops. It comes on plane extremely fast if I work the trim tabs
full and use the outdrive tilt. You almost don't even know the bow is
raising!

My question is...in lieu of the damn gas prices, I'm wondering if I
could get better mileage if I added larger trim tabs so that the boat
would plane at a slower speed. Right now, I have to get it to 3,000
rpm's to bring it down on plane.

Any thoughts?

Thanks!