Which is it, a long or short shaft Mercury?

mcgurk34

Cadet
Joined
Mar 3, 2004
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I am helping a friend replace his blown lower unit on a 1993 115HP Mercury in-line 4 cyl. My friend asked if he should switch to a long shaft or stick with what he has now. Frankly, I don't know if he has a long or short shaft now. First question, How do you measure the shaft length? I need to know which type he has now to order the replacement. Second question, How do you determine which lower unit would be right for a given boat? Is there some rule of thumb for shaft length to match a boat?<br />Thanks,<br />Mcgurk
 

roscoe

Supreme Mariner
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Oct 30, 2002
Messages
21,657
Re: Which is it, a long or short shaft Mercury?

THe shaft length is listed in the model number.<br />If you post it, someone can tell you, assuming he has the original lower unit on the motor.<br /><br />Also look here: shaft length picture
 

mellowyellow

Vice Admiral
Joined
Jun 8, 2002
Messages
5,327
Re: Which is it, a long or short shaft Mercury?

where motor bracket sits on transom to the anti-<br />ventalation/cavatation plate on L/U = current shaft<br />length.
 

mcgurk34

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Joined
Mar 3, 2004
Messages
22
Re: Which is it, a long or short shaft Mercury?

Thanks for the responses. I won't be able to get to the boat before next weekend and I'll post the model number after that. I take it from both of the replies and looking at the diagram, that the normal shaft length should place the cavitation plate in-line with the bottom of the transom. Well, thats simple enough to measure. Thanks again. <br /><br />McGurk
 
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