No clue how to trim motor

[Merc90HPnewbie]

Ok I'm relatively new to boating. I got a 1985 Glastron 16' fiberglass bowrider with a 90hp mercury outboard over a year ago. We've had a lot of fun with it (and I learned more than I wanted to know about boat and motor maintenance and repair but one thing still has me stumped. I am clueless on tilt/trimming the motor in or out. It doesn't appear to me to make much of a difference at all.<br />-At extremely low speeds (like the 5MPH no wake zone) it does nothing. <br />-At moderate speeds (around 15 mph) it does seem to have a bit of an effect. I can see a further to the horizon when I trim the motor in so I know it is bringing the bow down. And if I trim out too much I can't see anything so I know the bow is going up. <br />-Anything faster, and certainly at WOT (about 45 MPH) the angle of the motor seems to have no effect at all on the boat. It seems to me that the speed, attittude, handling, etc are all the same at all motor angles (up until the motor is so high out of the water that the prop is sticking out and spraying water all over). The boat doesn't seem to 'porpoise' at all, though in choppy water it can get a little bumpy&jumpy.<br />Am I being completely clueless here or what?<br />Thanks

 

[DJ]

Re: No clue how to trim motor

Some boats are not sensative to trim.

 

[rc581]

Re: No clue how to trim motor

merc90.proper tilt/trim is important. go to general outboard discussions, click on "best motor angle" and read what cobra 3.0 has to say. you will find it most interesting. good luck.....bob

 

[Merc90HPnewbie]

Re: No clue how to trim motor

Basically his advice was to go look at this article:<br /><br /> http://www.clubmarine.com.au/internet/clubmarine.nsf/docs/MG19-2+Technical <br /><br />I was expecting it to be like everything else I've read on trim, which assumes you can somehow see the outside of your boat while you are underway (impossible). This article does have some tips on setting the trim angle while realizing that you can't be looking at the side of your boat at the same time (eg: "As a rule of thumb, an indication of good calm water trim angles is when the steering goes light. Try it a few times. Trim in/down and out/up until you feel this freeing or lightening in the steering. ")<br /><br />I'll try a few of these things and see if I can get a better feel for the tilt angle adjustment. Part of the problem is I don't have a tilt angle indicator on the boat...

 

[agrazela]

Re: No clue how to trim motor

Merc90,<br /><br />I have a 15' bowrider with a 70hp mercury. I, too find that trim angle does little for "overall" performance...i.e., top speed, WOT rpm's, etc.<br /><br />What I do find is this: in calm water (i.e., lakes, or early morning on the bay), trimming out to hole number 2 gets me up on plane faster. I usually do this if fishing a lake or pulling a light tuber. Trimming out to hole number 3 gets me up on plane superfast, but I have to take longer turns to keep from ventilating the propeller...I only do this if pulling an adult tuber.<br /><br />In rough water (such as the bay in wind), I have to trim all the way in to hole number 1 in order to avoid taking a MAJOR pounding on the chop. The nose digs in sometimes in a big wake, but that's why I have a bilge pump!

 

[macshak]

Re: No clue how to trim motor

Wether this is right or not, here is what I do. When I launch, I usually trim all the way down. Then when I head out on the lake and hit full speed, I slowly trim up. Usually I can feel and hear when it is just right. I've noticed it also depends on how many I have on the boat and were they are sitting. I have a 78 Ebko 16' tri-hull with a 90 HP Merc.

 

[swist]

Re: No clue how to trim motor

I'm sure this is hull and motor (and load) dependent, but I was taught to get the boat on plane at full trim in (supposedly fastest planing time/least engine load) and then trim out watching the tach for max rpms (obviously stopping short of ventilating or porpoising).