Outboard Motor Mounting Height

[sreidvt]

Hi All,

I'm currently restoring an O-Day 23 and, since I know some folks here, I wondered if I might post a question about my boat which -- in some ways -- is similar to a CP 23.

I'm installing a new motor mount for my Honda 5 and Honda's recommendation, for a sail boat, is to have the cavitation plate about 2" below waterline. On my Mirage 20' the adjustable mount puts that plate about 8" under water (which seems to be fine except when I'm on the foredeck in high waves). I know that it shouldn't go too low because the idle port needs to stay above water but what heights have you folks gone with? I'm thinking something more like 4" to keep the prop in the water even when waves are high.

So....how low is your cavitation plate below the water and how well does that work for you?

Bob?

Thanks,

Sean

[crazycarl]

i've found that when it comes to sailboats, the deeper you can place the prop, the better.

the manufacturer recommendations are most likely for planing hulls.

sailboats will "hobby horse" in rough water and you don't want the prop clearing the surface. 

this is why o/b manufacturers offer long and extra long shafts.

CC

[sreidvt]

Hi Carl,

I agree. Honda's manual says the motor shouldn't be low enough to block the idle port. So that's the "low" limit for that motor at least. Any idea, Carl, how far your cav. plate is below water level (when the motor is down all the way)? Anyone else have a sense of that with their boat? I'm considering maybe 8" below water level instead of 2".

[jcatkeson]

I have just replaced a mount. If the motor is mounted too low, it cannot be withdrawn completely from the water for one of two reasons: it cannot be tilted or the mount will not allow the motor to be lifted high enough to get it completely out of the water. The mount that came with the boat did not allow the motor to tilted and locked. This was due to the motor head hitting the hull. I am aware of the Meed for getting the prop deep enough under power. A longer shaft won't work any better because the mount then does not lift the prop completely from the water. This leads to barnacles.