Posted by Bulldog98 on 02/04/23 - 7:04 PM
#1
I have a 1986 Outrage 25 that I have just repowered with a new 2022 Yamaha F300. Motor was broken-in today and did some testing. Hoping someone can help me with the correct height. I am running Yamaha Saltwater Series II 17p x 15 1/2 in diameter prop. I am turning 47 mph at 5700 rpms with two adults and 70 gallons of fuel, so I think the prop may be correct. However, I am getting a fair amount of spray from around the foot and the cavitation plate cannot be seen while running. The motor is mounted all the down, flush on the top of the transom. This is a 25” shaft motor. Boat handles like a dream. I am assuming the motor should be raised due to the presence of the spray to get optimal performance. If so, what hole should I move it to? Currently, it is in the top hole, so I have the option to raise the motor up 1, 2, or 3 holes.
Thanks,
Bulldog 98
Posted by Phil T on 02/05/23 - 1:03 PM
#2
The engine needs to be mounted so the anti-cav plate is 2" above the bottom of the keel. Typically this is "3 holes up", top bolt in the 4th hole counting down from the top.
The F300 has a WOT rpm of 6000.
Note raising the engine will increase RPM by ~125rpm for each hole raised due to less drag.
This is good because the engine is too low.
Once you raise the engine, re-test and report back.
Edited by Phil T on 02/05/23 - 1:05 PM
Posted by BCLedsinger on 03/02/23 - 12:26 PM
#3
Phil T wrote:
The engine needs to be mounted so the anti-cav plate is 2" above the bottom of the keel. Typically this is "3 holes up", top bolt in the 4th hole counting down from the top.
The F300 has a WOT rpm of 6000.
Note raising the engine will increase RPM by ~125rpm for each hole raised due to less drag.
This is good because the engine is too low.
Once you raise the engine, re-test and report back.
Any feed back on raising the motor?