Is mine long or short?

O

ontheplane

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Knew that would make you look!

I have an outboard for a tender that doesn't seem to go as well as it should for the power.

It measures 23" from the bottom of the cavitation plate to the point where the transom touches the mounting bracket.

I can't find a definitive answer on the internet as to whether this is a Long or Extra Long shaft, but one thing is for sure - I think it's too long for what I need!

Can anyone confirm what the correct lengths are for "Short", "Long" and "Extra Long" shaft engines please.

Thanks
 
short =15, long = 20, xlong = 25. 23 sounds odd. you have to measure perpendicularly to the cav plate, from the cav plate t the top edge of the transom. xlong is quite rare, you'd kinda know if you had one. What make/hp is it?
 
Quote from a forum post some time back:

Measure the transom of your boat, From the top to the keel will be either 15"/16", short or standard shaft. 20"/21" long shaft. On some sailing boats an Ultra Long Shaft is required this will mean a 25" transom. 3 hp and above all come in either short or long shaft. Most inflatables are short shaft as are many sailing dinghies, fishing/row boats, yacht auxiliary motors are often long shaft. You always need to check though!! If you are measuring the engine, then from the clamp where it sits on the transom to the cavitation plate directly above the prop will be 20/21" on a long shaft and 14-16" on a short shaft.
 
the way the measurements taken as described by jfm & cliveshep are quite right, whatever it is though you seemed to have diagnosed that it is too long anyway, and certainly that blunts performance! Really you need prop / gearbox just clear (below!) of boats transom line, but not much more than that!!!.
 
I sometimes pop my Auxilary 6hp long shaft on my 240 tender... it goes fine, but not half as well as a standard shaft 6hp would! In fact even one up it doesn't plane, which a std shaft would.

So its not that it is unusable... just not as good as it could be!!!

....
 
A shaft that is 5inches too long will work ok at very slow speeds but will have very much more drag at planing speeds. Would take many knots off the top speed of a 30knot boat, for example, like 10+knots off perhaps. so very inefficient in that scenario
 
Alas, no book. Sadly, the sort of outboard permaclutter using up my disc space includes the fact that the serial number of my first merc o/b (well, my Dad's, I was in single figures age-wise when he bort it in 1974) was 9037331. We sold it in 1979. It was a nice 200 (20hp, with the swept back leg), 1974 model. My first ToP (a 90ELPT) had serial # 5777855 and if anyone wants to sell it back to me (it went to Cornwall/Devon) I'll gladly buy it :-)
 
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It was a nice 200 (20hp, with the swept back leg), 1974 model.

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nice! sadly the sort of outboard that I get very excited about!!

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you two need to get out more, JFM I have great difficulty remembering the horse power never mind the serial number, /forums/images/graemlins/grin.gif
and on that subject, what's these two then? 9311445 and 9364656 both small merc's ,year and hp please /forums/images/graemlins/grin.gif
 
Yup, need to get out much more :-) Can't answer the question because serial numbers are not unique. There could be a Xhp and a Yhp with the same serial number. If you give us the hp rating as well, then we can tell you the year of the engine. I can tell from those numbers that the engines are Belgium built, not Wisconsin
 
the first one came with a cowl that says 7.5 and the latter is 9.8, although looking at the two side by side there doesn't appear to be much difference between them.
would it be displacement, larger jets in the carbs, or something else?
 
I think You should change Your Forum 'Handle'
Too many of Your Posts concern difficulty, ref getting 'On The Plane' /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif
 
Not at all.....

I have enormous difficulty getting "on the plane" which is why my handle is as it is - it's an aspiration not a regular occurrance.

It's a Yamaha 8hp I have re-measured it, and yup, from the underside of the transom clamp (where the outboard meets the transom) to the bottom of the cavitation plate is definately 23 (or perhaps 22) inches.

The problem is that the clamp base is angled slightly. The way I am measuring it is to clamp it onto a piece of wood, tip the engine to the vertical. Run a spirit level off the wood and measure from the bottom of the spirit level to the bottom of the cavitation plate - doing it that way gets me 22 inch

Just putting the tape on the transom clamp and running it paralell to the engine down to the cavitation plate gets me 23 inches.

So I'm guessing XLong??
 
I'd say it's a long not an extra long imho. Your spirit level method isn't quite how the manufs do it. They measure from AFT edge of transom top lip, which is say 1/2 inch lower than your spirit level point. So yours is 21.5inch. On smaller non planing outboards they often make them a bit longer than the official 20inch to get more grip in water, esp for sail drive type engines. It's only on a fast speedboat that it is important not to exceed the 20inch, and to have the cav plate no lower than the keel

Also the tilt angle of the engine affects the measurement a bit. so it isn't that accurate!

Ref your engines, yes the 9.8 /9.9 were identical with the 7.5, only difference is carb jets. 9311445 and 9364656 are both 1982 models, european built
 
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