TOPIC: Mark 35A - Transom Height

Looking for some outside objective opinions from mercury fans.

Building a boat to host the '59 Merc Mark 35A I have restored.

I have 'mocked up' the transom onto the engine stand and the cavitation plate is 1" below what will be the bottom of the boat, the transom is exactly 16" high.

I have attached a copy of the original owners manual specifications for engine height.

I'm leaning to step up the transom height to 16 1/2" or even to 17", the baot will be a pleasure cruiser only.

Any feedback much appreciated

Undecided.

keep the cav plate at or a hair above the transom I would not go below

I built my transom to be an 1" above the bottom of the hull when the motor was vertical.

Frank

I agree, keep the antiventillation plate even or just slightly above the bottom of the hull.

Thanks to all for responding. My concern is, as I'm sure you know, that the water pick up/inlet is on the underside of the antivent plate, didn't want to risk 'starving' the puppy of water.

You won't have anything to worry about at 1" above.

I run mk55's , same lower unit as yours...mine are all 1' above.
cav plate level is Fine but 1" below will slow you down a few mph

Thanks again one and all, gives me confidence to procede with raising the transom height a full inch.

I`ve got a Merc350-61 on my Sweet and it`s about 10mm over the bottom.
It gives me very heavy caviation problems turning the boat hard.
10-15 knots no problems, but due to the flat hull it raises up on edges of the transom and cavitate.
So racing straight a head no problems, turning: problems.

With those Mercs with the pickup on the underside of the AV plate you do have to be careful that you keep it close to the water. They can go up a bit, but not much. I would build the transom on the low side and then shim the motor to where it seems happiest. Much easier to shim the motor up than to trim the transom down...

Have 'bit the bullet' and built the transom 17" high, the cav plate will be 'flush' with the bottom of the keel. Figure a 35 horsepower Merc Mark 35A that's 51 years old won't be 'lifting' the boat out of the water.