# Short or long shaft ???



## stanimals2 (Mar 20, 2011)

OK stupid question but I have a 1995 Sylvan super swamper that has a 9.9 long shaft motor that was on it when I bought it used. The boat is rated for a 35 HP motor and I would like to go to a 25 or so for some of the bigger water, not talking about going fast and beating the rivets out of it just getting places a little quicker on big water. My question is how do I know if it has to have a long shaft or if a short shaft will work ? I have seen some good deals on some tiller 25 to 40 hp short shaft motors but how do I know if I can use them ?? Help please.

Thanks, Stan


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## smokercraft15 (May 21, 2011)

stanimals2 said:


> OK stupid question but I have a 1995 Sylvan super swamper that has a 9.9 long shaft motor that was on it when I bought it used. The boat is rated for a 35 HP motor and I would like to go to a 25 or so for some of the bigger water, not talking about going fast and beating the rivets out of it just getting places a little quicker on big water. My question is how do I know if it has to have a long shaft or if a short shaft will work ? I have seen some good deals on some tiller 25 to 40 hp short shaft motors but how do I know if I can use them ?? Help please.
> 
> Thanks, Stan



Outboard Motor Conversion From Long Shaft to Short Shaft
How to Measure a Long or Short Shaft Outboard Engine

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Short/Standard Shaft

Watercraft whose aft transoms measure 15 to 17 inches in height operate best with a short-shaft (or standard) outboard engine. Short-shaft engines are used with inflatable boats, canoes, small sailboats and small watercraft used for trolling.
Long Shaft

Watercraft whose aft transoms measure 18 to 21 inches are designed to use a long-shaft outboard engine. Long-shaft engines are suitable for johnboats, pontoons, sailboats and certain Carolina skiffs.
Extra-Long Shaft

Watercraft whose aft transoms measure 21 to 27 inches are best powered with an extra-long-shaft outboard engine. Extra-long-shaft engines are less common. They fit large barges, catamarans, sailboats and other watercraft with high aft transoms.


Read more: Short Shaft vs. Long Shaft Marine Outboard Motors | eHow.com http://www.ehow.com/facts_6867503_short-shaft-marine-outboard-motors.html#ixzz2B0v1GTNP


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## sherman51 (Apr 12, 2011)

yep, he pretty much said it all. measure your transom from where the engine sets on the transome to the bottom of the boat. this will give you the shaft length you will need. most fishing boats will take a long shaft which is 20". alot of your saltwater boats have a deeper transom requiring an extra long or 25" shaft. and like he said some boats can use the short shaft which is only 15".

but the only way to know for sure is to measure your boat. but i would just guess you need a long shaft, 20". if you get one to short its not going to perform like it should and would probably handle like crap. get one to long and your going to get to much drag and the cavation plate is going to be under water. and again your going to get poor performance.

i had a nice old mako center console, and i think the transom was like 24" so it took a extra long 25" shaft. i have a 15 ft starcraft tri hull open bow and the transome on it is like 19 1/2", so i have a long shaft 20" motor on it. good luck and let us know what you have.
sherman


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