TOPIC: RAISING MOTOR

Hey all,

Ive got my Mark 75 mounted up on my boat and running pretty good. I noticed that when i put the motor on the transom, the cavitation plate sits about 1.5" below the bottom of the boat. Also, when i run it with the motor trimmed in, there is a ton of spray coming from the lower end. I have to trim it out to the 3rd position to avoid the spray.


I was thinking about simply raising the motor and installing a 1" oak block under the transom clamp to take up the extra space. The hand screw clamps will still be roughly 3/4" below the top of the transom. I was then just going to bolt through the transom using the two mounting holes at the bottom of the motor clamp so nothing can move.

What do you guys think? I realize that the oak block adds no structural strength, but i thought it might be better than leaving a gap between the top of the transom and motor clamp.

I want it to be safe, but i also don't want to have to add material to my brand new transom over 1".

IF the keel is not to the back of the boat then raise it to even with the bottom and parallel to the bottom AND BOLT IT ON. drill holes in the middle of the slots . that way you can raise or lower it some.

...and yes to the oak block.

The old Dockbusters Short Shaft model was longer than 15", as I recall maybe 17-1/2" or something like that?

Anyway, what you want to do should work fine. I raised-up my old 1350, on a Sidewinder ski boat, probably 3/4" using spacer sticks. Worked great, didn't spray, got a nice turn of speed, too.

When you seal the thru-transom bolt holes, don't use RTV (silicone). Use a polyurethane sealant such as Boat-Life or use something like 3M 5200 sealer.

www.westmarine.com/boatlife--life-seal-sealant--P004_127_003_005

www.iboats.com/Marine-5200-Adhesive-Sealant-3m-Marine/dm/view_id.39220

These do not deteriorate in the presence of fuel/oil, such as will plain-old RTV. It'll keep nasty water out of your transom, along with rot.

Cheers.......ed