Shaft Size (length)??

[vampirefish]

Hello all. Well, I aquired a boat with a 1965 Merc OB 90hp inline 6. I've learned quite a bit about what this engine is all about -- especially what it is not. What I mean by this is that my step-dad (who gave me the boat/engine) thought it was a 1975 (it's a '65) and that it's a short shaft. So I take my lower unit to a shop (need replacement or repair) and I'm told it's a standard long shaft . So...what size is that?

 

[JB]

Re: Shaft Size (length)??

Short shafts are for 15" transoms, long shafts are for 20" transoms.<br /><br />Extra long are 25" and XXlong are 30".<br /><br />The measurement on the transom is from the top of the transom, vertically, to even with the bottom. On the engine it is from the part of the mount that contacts the top of the transom to the anti-ventilation plate (often mis-named cavitation plate).<br /><br />What is "standard"? At one time it was 15", then 20". The term is no longer used because there are so many lengths, and each is "standard" but only for boats with the matching transom height.<br /><br />Good luck.