On Fri, 05 Sep 2003 13:50:15 GMT, "Paul" wrote:

Ah, very interesting.

I'm beginning to experiment with more of the top end on my boat and have
discovered something that I wouldn't mind hearing a bit about (if you don't
mind me muscling in on your thread).

Running at about 20-28 knots my trim tabs do a fine job of keeping my bow
down to where I want it. At these speeds the trick seems to be to keep the
bow down. The port side wants to be especially high, I assume from engine
torque.

But once now I've opened it out and the bow has flattened right down on its
own, with no high side. I tried to lift it with the tabs and had the tabs
all the way backed off but the bow was still quite low.

I ran out of room (and courage) before I got to play with the drive trim.

I've played with the drive trim in the marina to see what it does (drives go
up, drives go down, drives go up, drives ... etc.) and I've read the manual
so here's what I figu

Once I get past the part where the tabs help keep it down, I can back off
the tabs and start to use the drive trim to get the bow up.

Does this sound about right?

Also, will I be able to level the bow (if one side wants to stay low) with
the drive trim?

I guess I'm asking, will the drive trim behave "sort of" like my trim tabs?

Boats are *so* not cars.


Paul, the drive trim will 'only' raise the bow, if one starts with the drive in
it's normal position, all the way down. Any raising of the drive will raise the
bow, assuming you are on plane.

Lets pretend the water is smooth and we are on plane with the trim tabs up all
the way and the drive trimmed down all the way. Trimming the drive up will now
raise the bow. Trimming it up enough will cause the boat to 'porpoise' if there
are any waves. I will trim the drive up a little, after I'm on plane. As Joe
said earlier in this thread, the engine rpm's will increase a little. The boat
becomes more 'efficient', so to speak.

Now, let's leave the drive trimmed all the way down for a moment, and focus on
the trim tab. I'm assuming you have two controls, one for each tab. If the boat
is on plane and you lower both tabs, you will lower the bow. In very smooth
water, this would not be very efficient, unless -- you have a lot of weight
(mother-in-law) in the stern of the boat causing the bow to be too high. If this
is the case, the trim tabs can be used to 'raise the stern', i.e. lower the bow.

When going from 'no wake' to get on plane, forcing the stern up with the trim
tabs can get you on plane more quickly, especially if you have a lot of weight
in the stern. "Forcing the stern up" would be the same as lowering the bow and
is accomplished by lowering the trim tabs.

Now, let's assume you're on plane, everything is fine, and your mother-in-law
moves to the starboard side of the boat. The port side is riding higher. By
lowering the starboard trim tab, a little, you can raise the starboard side of
the boat, thus 'trimming' it. BE VERY CAREFUL DOING THIS! The trim tabs have a
tremendous effect on the boat, and the effect occurs very rapidly when at speed.
Use only small corrections with the trim tabs when on plane, or you can flip
things right out of the boat, like people!

Hope this helps somewhat!

John
On the 'Poco Loco' out of Deale, MD