bcarpman

This may sound like nit-picking, but I'm wondering that it might be significant with today's gas prices.

I have a small boat (26ft) and sometimes go distances on pretty choppy water (3ft washboard). In order to have an acceptable ride, I have to plant the bow pretty hard. Up until now I've been adjusting the drive to the positive trim angle that gives me best speed, then dropping the tabs to smooth out the ride.

I'm wondering if I wouldn't be better off running negative drive trim with little or no tabs. Anyone have any rules of thumb for this? Which is more efficient? I would assume the drive trim is just adjusting the attitude of the boat and hence doing the same thing the tabs are doing, but without the drag???

thanks

Knot 4 Me

Drives neutral, tabs down enough to smooth out ride.

StillHaulin@63

I run a small 23' hull offshore around the Channel Islands in California.

I have concluded that in 1-2' waves with 3-4' swells, my best ride is provided by a 4-blade prop while leaving my tabs set at neutral or just slightly negative (-2-4*), and using just the drive trim to control the hull attitude. The stern lifting tendancies of the 4-blade seem to provide a level hull attitude which makes the rougher waters quite palatable, and the drive trim adjustments between waves and swells allows excellent throttle and bow control.

Besides, when your running hard in the open sea, there's no time to be screwin' with the tabs

bcarpman

By neutral, do you mean prop shaft parallel to the hull? I know on smooth water I get the best speed with the prop in a significantly positive trim.

thanks

Dave M

Yes, neutral = level with bottom. I think this will vary with different hulls.

In the conditions you described I would run neutral on the tabs and SLIGHTLY positive on the trim.

StillHaulin@63

In offshore waters, I've never felt that I could set the drive trim ... and leave it!

The constantly changing water conditions require constant adjustment of the trim, and no single setting will provide a consistant ride. From simply getting on plane, changing running angles, or approaching swells or wakes, the trim button gets almost as much adjustment as the throttle.

Relating to tabs, I was told that by keeping them at neutral, your eliminating most of the drag and extending the hull's length slightly. That seems to be the case, since when they're raised to a positive position, the boat feels much lighter and even smaller waves can become jarring.

bcarpman

I guess I need a trim switch on my throttle!

Great, now for the first time, I can't wait for some rough water.

Payton

If you have enough time to adjust your trim while running in rough water, you're to going fast enough. Once I get my boat running and launching how I want. all I touch are the thottles. I don't think you want much tab or you will send the bow down to fast and possibly stuff into the oncoming wave. But you want enough to extend the running surface. And you want enough trim to make the boat fly level.

michigan troll

Every boat is different. You will have to find it your self by setting the drive to N then adjust tabs. Note the speed and RPM's. Then readjust with the tabs at N and drive adjusted accordingly for ride at the same speed as before and note the RPM's.
Which ever has the lower speed for the same RPM's is your worst mpg.

Jim

StillHaulin@63

Once you taste it, you'll get quite bored with "pegging the throttle" and holding on