Trim - concept?

[RIJIMMY]

Hello,

the boats we owned growing up did not have trim function on the motor. I'm not sure what I should be doing with the trim other than lifting my motor out of the water. My boat does not have trim tabs.

What should I be doing? Should I leave the trim in the middle, up? down? What conditions warrant moving it?
Any advice appreciated!

[RIROCKHOUND]

You can try fiddling with it, Sometimes almost all the way down will give you a better ride...

get a flat calm day, get on a straight shot, and get up to cruising speed. then fiddle up/down a hair and see how she responds. Might ride better with the bow up a bit or not...

9/10 out of ten on OB's I just leave it down all the way unless I;m working very shallow water...

[Mr. Sandman]

I use mine often to fine tune the boats trim under way while in conjunction with the trim tabs. Tilting the motor up will lift the bow somewhat. If you are heading into a chop and want to pick up the nose a little just raise the motor a little while underway. The trim tabs are better to reduce any roll angle induced by the engine torque or incorrect boat loading.
The trim tabs can also be used to move the bow up and down but most are better at moving the bow down and taking out roll.
For minimum resistance, (ie best gas miliage) try an use as LITTLE trim tabs as possible, if you can adjust the boat trim the way you like it with the engine tilt you will be running most efficiently.

Normallyhere is what I do: I get the boat up to the cruising spreed I intend to move along at, then I lift the tabs all the way UP (ie out of the water) then I trim the boat with the motor to the ideal trim (bow up/bow down) angle for the sea condition, and finally I take off any roll with the one tab. This works for me...you mileage will vary

[capecodder]

If you look at the motor in the fully down position, the prop is actually pointed slightly down as opposed to exactly level in the water. This will have the effect of pushing the stern up (bow down) which gets you on plane faster. It will also increase the amount of torque resulting (single motor) in a pull or lean to port. In this position, when on plane, not all of the props power will be translated into forward push as some will be used to push down the bow.

When on plane, raise the engine until the prop is pushing parallel to the water surface. This will raise the bow slightly and use all of the engines power to push the boat forward. This will result in increasing the RPMs at the same power setting. It is more efficient. If you go too far, some of the power is wasted in the other way.

Here is what I do. I keep the engine all the way down until on plane. Then I raise it and watch as the RPMs increase. Usually this increases my RPM by about 100 -200 at a given throttle setting. See how the boat is riding in the conditions you are in and adjust from there. Too far and you will cavitate.

It takes a bit of experimentation to get it where you want it. Also, the closer you get to level the less you will see the effect of the torque resulting in a lean.

[RIJIMMY]

as always - great responses. thanks

[fishaholic18]

Take off with trim all the way down, prop will dig in better with motor down. Once on plane, trim up until prop starts to cavitate, drop trim down until cavitation stops, motor should be easier to stear, run more efficiant, and you should be able to get max rpm's now.. Trim down a little if prop cavitates while cornering. Just watch your tach, play with it, you'll learn what your boat likes best.

[stiff tip]

capecodder. hit it ex-zackly.......trim under way to peek rpm....

[striperman36]

I agree

[MTC]

In a following sea most boats run better and safer with the bow up... trim up as much as you can without cavitating. In a head sea you could put your nose into it some to let the vee of the bow cut the waves some...