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Author Topic:   Shaft Size--Montaulk 17 1977
GSCAT posted 07-17-2003 08:00 AM ET (US)   Profile for GSCAT   Send Email to GSCAT  
I am sure this basic question will bother some of you seasoned pros, but I have searched this forum and not found the answer.
I am looking at a 2001 Johnson 90hp to put on my 77 montaulk.
Shaft size for this engine is 20". WILL THIS WORK?
How do you measure shaft size when looking at engines.

Thank you.
whalersman posted 07-17-2003 11:35 PM ET (US)     Profile for whalersman  Send Email to whalersman     

The Montauk needs a "Long Shaft"... That would be 20"...

Regular or Short Shaft = 15"
Long Shaft = 20"
Extra Long Shaft = 25"

I think there may even be one longer but maybe someone else can expand on my knowledge...

Joe Kriz

Tom W Clark posted 07-18-2003 09:57 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

As Joe points out, you need a 20" shaft motor for a Montauk.

It's best to avoid using terms like "short shaft" or "long shaft" because these can be ambiguous as the terms have changed through the years as outboards have gotten larger.

In the "old days" it was:

15" -- short shaft

20" -- long shaft

25" -- extra long shaft

When outboards started to get bigger it became:

15" -- short shaft

20" -- regular shaft

25" -- long shaft

30" -- extra long shaft

In Europe there's even a 22.5" shaft length! I have no idea what they call that.

Using inches to describe a shaft length avoids this confusion and "cuts to the chase" when figuring what will work on what boat. It's important to understand that shaft length refers to the approximate vertical height of a boat's transom that will work with a given outboard. It is not a precise number that is measured form point A to point B.

In general, a motor's shaft length will equal the distance measured from the underside on the motor mounting bracket to an inch or two above the cavitation plate.

whalersman posted 07-18-2003 01:32 PM ET (US)     Profile for whalersman  Send Email to whalersman     
Thanks Tom,

I must be getting old....

My 1985 Evinrude 150 as an "X" in the serial number for "Extra Long Shaft"... 25"...

My 1985 Evinrude 70 has an "L" in the serial number for "Long Shaft".. 20"...

I knew something had changed later, not sure when, when they came out with that 30" shaft model..


jimh posted 07-19-2003 09:18 AM ET (US)     Profile for jimh  Send Email to jimh     
The answer to transom height is contained in the listing of specifications for 9-22 foot Boston Whaler hulls that is found in the Reference section. It is also in the Reference section article on the 16/17-foot hulls.

There is a great deal of information that has been collected, organized, researched, and presented in the Reference section. While the forum contains much information, it is not the exclusive source of information on this website.

Regarding posting public questions and soliciting private responses, this has always struck me as rude. The whole nature of the forum is to conduct an open discussion. If everyone just posted questions and had the answers emailed to them there would be nothing to read here. Therefore, this practice is strongly discouraged. If you have posted a question to the forum you should anticipate having to return to the forum to find the answer. That is how forums work.

By participation in a open discussion there is also the benefit of peer review. Perhaps someone mails you a private response, but it is incorrect. Had this been posted to the message thread it would be quickly corrected by others.


We now have this thread posted to two forums, and people have provided answers to your inquiry in both.

Again, posting the same article to multiple forumsis strongly DISCOURAGED.

jimh posted 07-19-2003 09:20 AM ET (US)     Profile for jimh  Send Email to jimh     
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