From too little to too much?

[Gene B.]

After a couple of years of sailing/motorsailing on the Mississippi River I decided to go from a two stroke to a four; from 8hp to 15. The four stroke is considerably heavier,around 130lbs and also has a high torque gearcase/10" prop. Mercury Bigfoot longshaft. I have a new heavy duty mount(91/2") travel compared to the old one which was 13" and spooky. Has anyone had any experiences to share because this is going to be a major job. ie. laying in alot of fiberglass at the lower drain area to accept the 3/8" bolts that I feel this mount needs,plus backing plates to lower the stress on the hull. Will this screw up the center of gravity on this boat? A 15 hp 4 stroke weighs the same as a 9.9 4 stroke. Any ideas will be greatly appreciated. I'm keeping the 8hp just in case.

 

[Larry Mongeon]

Same Gene

No pun intended. I have a 1974 H25 with a 15HP merc4. I have been using the factory motor mount with no problems. The one thing I did was order a new " Work Prop " (thats what merc calls it) designed for sailboats or displacement hulls. It is a perfect combo for my boat. I also have electric start and charger so it makes life real easy. I can push hull speed at approx 1/4 throttle and there are no stress cracks or problems on transom. Hope this helps.enjoy your new iron genny

 

[Steve Dion]

That what we had on our H'25 too.

Gene:We also had a 4 stroke Honda 9.9 on our H'25. Worked well with the stock mount. With the additional weight I would think that a new mount would be in order. I would want this just to make lifting the engine easier. I would use a largeest piece of plywood 5/8-3/4" that will fit. A good coat of varnish or epoxy in case it gets water or moisture would be a good idea too. Like Larry said the stock mount should hold the load if you do not open it up, but I think your idea of a larger mount is prudent.