How to trim a v-bottom at high speed?
 

We drove our FORMULA 353 Fastech by rough water
up to speed about 85 mls/h.
In that time I try to find the best set up between speed, RPM
and comfort. I asked me how would a race driver trim the
boat. The Drives more in or out, Trim Tabs up or down?
I would like to learn more about driving.
Thanks for any information!
Joe

Welcome to OSO. Well it's not an easy question to answer. People drive their boats differently, and all boats are different..

One thing I would suggest is, to sign up for Tres Martins driving school. There you can learn alot about your boat and how to drive it fast and safe.

Also. If you haven't, try posting your question in the Formula forum.

Keep trimming up the drives until you find max rpm and speed. When the speed drops but the rpm keeps rising you are over trimmed. Tabs are for leveling the boat only unless you are in rough seas and not looking for max speed.

I like to use drive trim more than tab, but thats just me. Obviously there are scenerios where running a little tab improves the ride/handling. Big water, head seas, I'll run the drives neutral or slightly negative, maybe a bit of tab. Following seas, I normally run drives nuetral or a bit positive, and no tab.

Following seas, too much negative trim, or too much tab=STUFF.

My theory on tabs is that say you are running thru some chop. The tabs work to keep the bow planted thru the chop. But in big water, where the boat is really airing out, when it lands back into the water transom first, the tabs being down will want to violently slam the nose back down. Where as keeping the tabs level or up, and the drives negative, when it re-enters the water transom first, the bow will come down more naturally, without "tripping" if that makes any sense. Not too mention that if the boat tends to land more towards the port or starboard side, the excessive negative tab can really upset the landing.

I guess what I am saying, is too much negative tab can be dangerous at high speeds.. I would like to take Tres driving course though, and learn the right way.

i have a 242, so its a bit of a different animal than your larger boat, but i run mine very similar to mild thunder. if the water is getting a bit big, i'll usually run trim a bit negative, and tabs level or just a hair down. the trim being a little negative and tabs level help to stabilize the boat and keep the bow from plowing and hitting hard. when i get out on nice water and open up, i pick totally up on the tabs (unless you have chine walk problems), and run the drive a bit positive. the boat levels out beautifully at higher speeds. i do however get some porpoising if i trim the drive too high, and don't have enough throttle to keep speed. i'm attributing it to the stern is too low in the water yet (b/c of slower speed), and the bow is flying high b/c of the trim angle. you can play that by the seat of your pants and trim back down a hair to get rid of the porpoising. i'm still messing with some prop issues that will hopefully get rid of the porpoising problem.

Thanks for all your response.
I am looking forward for the next run out on the water.
Learning by doing is the best, but with some help it is much better!

Index your drives and tabs so you know where neutral is. Assuming its a twin step run with the drives even or a lil up. Use the tabs in big water to settle the boat.

A FasTech is not a Vee Bottom. A FasTech is a STEPPED Vee. There's a difference.

But as has been stated, for top speed pull the tabs all the way up out of the water, run wide open throttle at slightly negative trim and then start bumping the trim up, allowing the boat to settle after each change. Watch the GPS and note the trim setting that delivers top speed.

Also, turning a step-bottom at high speeds can be dangerous if you aren't used to the boat. Trimming "in" and bringing the bow down while turning can result in a spin. Don't drive aggressively until you are familiar with your boat's habits.

MC