Wot?

Is WOT measured with no trim or is WOT measured at max trim?

This has never been clear to me because of the denseness of my head.:o

i would think it would be at highest trim you can comfortably drive and control boat.

WOT is max RPM's the engine should develop. Trim in, trim out, number of people in the boat, fishing equipment all effect WOT. The key is not to exceed WOT RPM's. You prop your boat to obtain, yet not exceed WOT, the way your boat is normally configured. So if you always fish by yourself, and propped your boat that way, and a weekend came up that you were going to have 3 or 4 people in the boat and tow a skier, you should change props out to a lower pitch or diameter.

When you max the gas your engine will run at WOT. Its not going to run any faster. The engine is turning at max prm's. The other stuff affects how much of that power gets transferred to the water, and thus affects your max speed. You can try to reduce parasitic drag by reducing the number of people, trim, tilt, blade pitch etc. and gain top speed, however your still at WOT.

Lets look at the affects of weight on engine WOT/RPM's. You can put a 25hp motor on a ton of different boats. Everything from boats that weigh a couple hundred pounds up a thousands of pounds. If we go off teh assumption that more weight means the engine runs at lsss than WOT the heavier the load the lower the max rpms we could get out of the enigne. Does that mean there is a weight at which point the engine stops turning? What if we put that motor on a barge, will it stop running? No, it will still run at WOT, however you wont go very far very fast. Lets take it the other way, we lighten the load, say to a 5 pound boat, does that mean the max rpms will increase to infinite? No, the engine will only run up to WOT, wide open trottle. Max WOT is not related to boat wieght, trim or any of that other stuff. It is however a function of air/fuel mixture ratio, engine timing, spark timing, octane, etc.

Its a common misunderstanding.

We call it " on the pad " down here.

Wide open throttle or WOT as it's referred to in the forums quite often is the maximum throw of the fuel control. Don't mix it up with Max RPMs. The two are used together to measure the performance of the prop or effeciency of power transfer to the water.

You should be measuring your maximum RPMs at WOT with your boat trimmed for running, not trimmed in all the way, or out all the way, but trimmed for the best ride and neutral steering. This also means, as others have said, trimmed (as in loaded) for your normal day on the water.