Mercury 85 hp 1978 restoration, prop question and rudder thing, hull paint cracking

[andrewbabich]

My friend just inherited a 1978 tri hull with an 85 hp black merc on it. I assume the motor is 1978 as well, but not sure, and I'm in charge of getting it back to running condition. It was ran as a recreational lobster boat the last few years and its in baaad shape.

I have a couple 13 3/4 x 15 Johnson omc props from that era. Are they interchangable.

The prop needs replacing and

The rudder/ stabilzer tab thingy that hangs off the outboard near the top of the prop is all corroded and needs replacing. (whats this thing called).

The steering cable is shot and needs replacing too, unless I can un seize it. Any tips?

The below waterline area of the hull is red painted and all cracked and nasty. What should I do, can I sand it down, does in need replacing? I don't know why a fiberglass boat has cracking paint.

 

[Bondo]

Re: Mercury 85 hp 1978 restoration, prop question and rudder thing, hull paint crack

I have a couple 13 3/4 x 15 Johnson omc props from that era. Are they interchangable.

Ayuh,... Donno, try 1...

The rudder/ stabilzer tab thingy that hangs off the outboard near the top of the prop is all corroded and needs replacing. (whats this thing called).

Torque tab, or trim tab...

The steering cable is shot and needs replacing too, unless I can un seize it. Any tips?

Replace it, they don't last forever...

The below waterline area of the hull is red painted and all cracked and nasty. What should I do, can I sand it down, does in need replacing? I don't know why a fiberglass boat has cracking paint.

It's probably bottom paint that stops the critters from living on the bottom..

 

[jbcurt00]

Re: Mercury 85 hp 1978 restoration, prop question and rudder thing, hull paint crack

Pix are always helpful & get a serial # off the motor's transom bracket or somewhere under the cowl, around or on the powerhead.

Bond-O, & many others, can & will be very helpful,even if you have to gut the boat & strip it down to nothing but bare fiberglass..

 

[Chris1956]

Re: Mercury 85 hp 1978 restoration, prop question and rudder thing, hull paint crack

Those Johnny props may fit the Merc, but will likely require some engineering on your part to make it happen. First the Prop hub diameter needs to be 4-1/4". The splines on the Merc propshaft are shorter than the Johnny Prop, but that will likely not be a real issue. You will need to fabricate a thrust washer and some spacers to sanwich the prop into the right place. I would recommend buying a new aluminum prop for that very motor, on sale instead. You can mess with the existing props later.

The engine wiring on that motor is probably shot. New harnesses are avail on the web.