Re: tri-hull
Planing is when the boat is going at a sufficient speed to allow it to skim on top of the water rather than plow through it. This is the most efficient way for a boat to move as it cuts resistance. You have to have enough power to move the boat fast enough for this to happen. For most average boats of average load, this speed is usually high teens/low twenties. Too little power and the boat just plows through, which is very hard on the motor and wastes fuel.<br /><br />Trim is the angle of attack the propeller has in the water while the boat is on plane. In a perfect world the prop's thrust vector is roughly parallel to the waters surface, and the boat is riding on the last 1/3rd of the hull at the rear of the boat. In the real world, the prop thrust is often either pointing downward or upward, which affects efficiency, and is dictated by load placement in the boat, hull design, prop design, and horsepower. Again, too small of an outboard results in a thrust vector that is pointed downward, usually in an attempt to bring the bow down because the bow is pointing to the sky because there is not enough power to get it on plane.<br /><br />These are things that becom immediatly apparant when you get out on the water. The best way to learn is to go out with someone else on their properly set up boat and have them show you what this stuff means.<br /><br />As for old motors, they are a crap shoot unless you are mechanically inclined or have a buddy that is mechanically inclined. You either score an awesome deal with old outboards or end up in living hell. Typically you can find old 2 stroke 100+ hp motors that run for $500-$1000. There are cheaper ones, but unless a little old lady is selling it, you end up having to fix stuff on it.<br /><br />My personal belief is if a person is buying a cheap boat that needs work, and does not know much about motors, they should get a boat with a running motor and a thrashed hull. It is easier for a beginner to fix a hull than a motor. If you are going to get an old motor, at least get one with sufficient power. There is no need to sink tons of money into a motor that will not do what you need it to. There is no such thing as too much power. A higher horsepower motor will live longer, and give you better economy at half throttle than a small motor that is being wound out the entire time. Good luck...
