We recently bought a new Yamaha 115 HP four stroke long shaft [ F115AETL ] to fit onto a Yamaha 23 foot long boat. On fitting the engine on the transom we find that the engine is cavitating a bit - we can lower the engine into the water by cutting off some of the transom - I think about 2 inches will do the trick. My question to the forum is how far above the water must the engine be in order for water not back-washing into the engine ( or how far into the water can you put the engine ). Is there some guidelines? At present the rubber seal around the engine cover is about 12 inches above the water level when the boat is sitting at rest in the water. I would appreciate some advice and thanks in advance.<br /><br />I have been quote for a shaft / leg extension to 25 inches to cost about AU$4000 [ = US$2000 ]. We made the mistake of not getting XL from the start.
