JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

[cpahl_99]

I HAVE A 14 FOOT JON BOAT WITH A 18 INCH TRANSOM. WOULD IT BE SAFE TO HAVE A SHORT SHAFT MOTOR

 

[JasonJ]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

How are you measuring the transom? If you run a plumline from transom top and let it hang and use a straight-edge that is held against the bottom and have it intersect with the plumline, measure along the line to where the straight-edge meets the line, it will be a shorter distance than if you are holding the tape against the transom all the way to the bottom.

 

[Johnshan1]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

my boat measures 18" if you measure the transom however if you measure the way JasonJ tells us it is 15"<br /><br />I would say you need a 15" shaft, I would still measure the way Jason explains just to make sure.<br />-John

 

[Tracy Coleman]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

You don't say what engine you want to use, but as a rule smaller engines 9.9-20 don't like to have the cavatation plate above the bottom of the boat. Most motors will run slightly tucked under to keep from porpoising. I would rather jack up the engine with a 1" block on top of the transom using the long shaft than to have to cut 1"-2" off the 18" transom to get the short shaft to run right.<br />Backfire

 

[Clams Canino]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

We're talking about a Jon-boat here. So long as you can get the propeller wet, and the waterpump inlet under water, it'll be suitable for it's intended purpose. <br /><br />Now if your entering some super-secret NMMA sactioned American Jon-Boat nationals event, then we need to talk performance. <br /><br />I'd go with a 20" to make sure all is under water.<br /><br />-W

 

[rickdb1boat]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

If it's 18", it needs a long shaft. You MAY get by with the short shaft if you have alot of weight in the stern of the boat, but...

 

[Johnshan1]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

Ya know, if you measure a short shaft transom most come out to 18" if you measure from the bottom to the clamping area.<br /><br />This is due to the angle of the transom. If the transom is perfectly straight with no angle to it, then yes a long shaft would be needed.<br /><br />However an angled transom would measure 18" on all major boats needing a 15" shaft.<br /><br />Bottom line is we dont know how he measured, so he needs to do with this info as he deems fit.<br />-John

 

[cpahl_99]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

I MEASURED WITH A TAPE MEASURE AGAINST THE TRANSOM FROM THE TOP WHERE THE MOTOR SITS ON TO THE VERY BOTTOM OF THE BOAT. RIGHT NOW I HAVE A 1956 7.5 JOHNSON SEAHORSE,BY THE WAY I AM SELLING, THE CATAVATION? PLATE IS JUST BARELY BELOW THE BOTTOM EDGE OF THE BOAT. I MEASURED MY SISTERS BOAT THE SAME WAY AND GOT 16 IN, BECAUSE HER TRANSOM IS A BIT DIFFERENT, HER CATAVATION? PLATE IS ABOUT A INCH BELOW THE BOTTOM,SO I THINK THEY BOTH MUST BE SHORT SHAFT.<br /><br />BY THE WAY, I JUST PURCHASED A 9.9 MERC 2 STROKE.<br />I KNOW THIS IS A GOOD ENGINE, ANYONE OUT THERE HAVE EXPERIENCES WITH THIS OR OTHER MERCS

 

[cobra 3.0]

Re: JON WITH A 18 INCH TRANSOM, WHAT LENGTH OF SHAFT?

A standard shaft will do.