20' seafari IO to O/B transom notch and outboard height

[samcfuller06]

Hi all, im looking for some guidance on cutting the notch in my 20' seafari transom. Boat had a straight 6 mercruiser and alpha one outdrive, both of which were fairly used up. I have a 135 Mercury Black Max that i want to put in their place. My question is, what are the standard notch dimensions on those of you currently running a notched transom ? Width of the notch Left to right, and how far up from the bottom of the vee, or down from the top of transom does the notch begin at ? I believe the merc has a 25" shaft. I'm going to verify that again in the morning, is there a rule of thumb with regard how high above the bottom of the vee the outboards cavitation plate should be ? Any help in making sure i set the outboard at the right height on the first go round would be very much appreciated, thanks in advance
Sam

[SailorChlud]

Hi, Sam - Last fall I had my transom redone with a 25 inch height, and wished it had been done to 26 or 27 inches, so the motor has more adjustment up. I have a 25 inch Johnson 115hp on it, and the best advice from the site was to start the motor mounted with the AV plate at 1.5 inches above the keel. Right now mine is at about 1 inch up and will be adjusting it up one more hole (3/4 inch) in the near future.

I would be happy to measure my notch for you this weekend. What are you planning on for the splashwell configuration?

My boat is a 1972 Seafari 20.

John

[samcfuller06]

John, thanks for the advice, i cut it at 26 and a quarter today. Unfortunately a large portion of the transom was wet, so i stripped the transom interior ply and removed the two seats and old IO ingine box, flush cut all the engine box coaming and am preparing to make template in the morning to relaminate the transom with two layers of 3/4" marine ply. Im also goung to glass in two knees coming up from the main stringers which will sit just outboard of the OB mounting bracket/bolt configuration. The knees will be incorporated into a splash well, once i get to that point. Im planning to put two pieces of ss plate on inner and outer transom to bolt through after decoring the engine hardware holes and filling with hull and deck. Was really hoping the transom would be moderately intact but not the case. I cut the notch 32" wide, at the top, tapering to about 28 where the OB will sit