Trim/Pitch

[Rattle-]

I have to ask...<br /> When I bought the Boat/Motor from my buddy, he said you may have to adjust the "trim" to where you want it...<br />There is a bracket in the back of the motor, with 5 or 6 spaces for a pin that inserts, that the motor rests on. Is this what he was talking about, reguarding the pitch of the prop, and the way the boat handles?<br /> I have a small 12 ft. Springbok, with a 9.9 Johnson, and would like to have everything where its supposed to be. Thanks to everyone for their help. Eventually, these stupid questions will stop...<br /><br />Kerry

 

[Paul Moir]

Re: Trim/Pitch

Generally speaking, you should set it so you have the cavitation plate just above the propeller flat with the bottom of the hull. That is, if you stuck a board off the bottom of the hull, it should be parallel with the cavitation (actually, anti-ventilation) plate.<br />Specifically speaking, borrow a handheld GPS and figure out which hole makes you go the fastest when the boat is loaded normally.

 

[Rattle-]

Re: Trim/Pitch

Hey Paul;<br />You must be getting tired of the questions, but thanks for the info on all that I'm asking. Cavitating, must be unecessary disturbance, I'm guessing...<br /> Three goofs fishing in a 12 ft. Springbok, is not a big deal, but if I'm shellin' out the Bucks for the whole deal, then I want to know.<br /> We have to have things working like they're supposed to.<br />There are only 5 or 6 positions for trim adjustments, and I think I've got it close..<br /> Michelle is getting me me a GPS (Garmin/Rhino) for Christmas! We'll not get lost on Cloud Lake ( or any other) next year.<br /><br />Kerry

 

[Paul Moir]

Re: Trim/Pitch

Hey, we take all kinds of questions here. Lots of them too.<br />Cavitation is what happens when you have such a low pressure in water that the water vaporizes producing tiny bubbles that near instantly collapse. It's essentially a speed limit on anything moving through water. Fortunetly, the number is quite high (~140mph) so that doesn't affect boats, but it does limit the tip speed of propellers. If the tip of the prop exceeds this speed, then it cavitates and spins freely in a water/water vapor froth, loosing it's 'grip' on the water.<br /><br />This is not what the 'cavitation' plate prevents. Rather, it keeps air from getting sucked into the propeller from the surface, causing much the same effect: the propeller spins freely in a air/water froth and looses it's 'grip' on the water. So properly called, it's an anti-ventilation plate. But if you go talk to your local dealer about your anti-ventiation plate, he probably give you a look like you have two heads. <br /><br />Cloud Lake looks real fine. So does the Garmin Rhino. I've been ofshore in thick pea soup a few times with a much simpler handheld (Garmin 310), and it's been an essential thing to have.