Long Shaft on Short Shaft designed Rib

[Bigplumbs]

Amongst my small fleet I have a nice little Valliant D340 Rib that currently has a 15 hp Mariner 4 stroke on the back that is pull start and fixed trim. I use this boat for various small trips and would like to switch out the engine for a Power Tilt and Trim and Electric Start. I have found a nice one for a reasonable price but it is long shaft, This little rib is designed for short shaft.

So with a 4 inch difference I was wondering if I could plant say 2 inches on the top of my Transom and then only have 2 inches too long at the bottom of the hull. Would this be silly or would it go ok.

Interested in views particularly of anyone that might have done something similar

 

[kashurst]

I had a Valiant 320 -with a 15Hp outboard and the transom used to flex and it started cracking. I think if you just raise the proposed new outboard, the transom will be overloaded and you will get cracking at the base and it will start to pull away from the glued on supports on the tubes - especially if you give it the beans.

If you make the transom taller and reinforce it with struts from the top of the transom to the deck (triangulate the forces) it should be OK. The difference in centre of gravity won't matter, once you have a few people on board.

 

[Kola]

As above.
Tried it once with a 15hp, there is a surprising amount of torque in 15hp!
It did work, but never really felt comfortable with it.