I had a 25 footer I fitted with a Yamaha 9.9 XL (25") shaft. It worked perfectly and rarely popped out of the water, even in 30+ knot
conditions. When I first purchased the boat - which had been cruised up and down the east coast
by the po - it was fitted with an 8 hp short shaft on this funky sliding arrangement. I only ever motored with that combo inside a marina and it worked perfectly but I had serious doubts it would stay that way in rougher water. Another factor to consider that unless the engine
is centred on the transom, it will also have for more tendency to pop the prop out of the water as the boat rolls.