Correct Mounting on transom

[John]

Hi, i have had lots of problems with my 55ae particurly with the prop size.

i have kind of sorted it out and got the best possible rpms. However a friend who has just brought a boat and mounted an engine on the back and it was not running right. he was told to cut the transom out about 2 inches and then remount the engine. He did this and the boat flies along now.

If i was to do the same would i get better results. One thing i do notice is that when i trim the engine (baring in mind its manual tilt) down to the bottom notch it pushes the boat better. My boat doesn't plane at all. but it should go much faster than it does.

I tried looking for a diagram about how to mount the engine and how to get the cavitation plate in the right place but i could not find one. Does anyone know where one is or could someone point me in the right direction so i can sort this little problem out.

Many thanks in advance.

John

[Dennisg]

hi John, the cavitation plate should be even with the bottom of the boat when the motor is at 90 degrees to the water, with boat floating, not on the trailer.(The motor should not be trimed IN more than this, ever) A inch below is acceptable, but not more than a inch. It is all spelled out in the installiation manuel from yamaha, or for that matter, any outboarb manufactuer. I am pretty sure that you can find the installiation manuel on this site, if you hunt arround for it.
Dennis

[Ken]

John,
In general, you want to mount the motor on the transom as high as you can w/o the prop ventilating.
Also, in general, if your boat is a v-bottom, you want the cavitation plate just about in line with the keel when the motor is at right angles to the keel.
The lower you go with the motor, the more drag from water resistance, and the slower you will go.
On my Pathfinder, there is a small cut-out area just in front of the motor at the bottom of the hull. This allows the water to "well-up" when on plane, and thus the motor cavitation plate is actually higher than the keel.
When all is said and done, when you are up on plane and trimmed out and WOT, you want the cavitation plate riding just on top of the water surface.
Hope this helps [img]smile.gif[/img] ,
Ken K