# Standard outboard shaft length?



## birdsnest (Oct 2, 2007)

I saw a good deal on a Yamaha 90HP with a 20" shaft and the another on a 115HP with a 25" shaft. Where do you measure it from to see what my boat would need?


----------



## sealark (Sep 27, 2007)

Would help to know what boat you have.


----------



## birdsnest (Oct 2, 2007)

Sorry. I have a 24' Pontoon boat


----------



## sealark (Sep 27, 2007)

I would think a 25" would be what you need. Call the boat manufacturer to be sure.


----------



## Mikvi (Mar 11, 2008)

20" usually used on Bass boats. 25" standard on offshore, with some 30". 30" seen more as a center motor in triple setups these days. None of these are hard and fast rules, just guidelines.


----------



## murfpcola (Aug 28, 2012)

Does your pontoon have an old motor on it now? If so yo measure from the bracket where it sits on the "transom" to the cavitation plate. This is also assuming the motor on it now is the correct length. As stated contacting the manufacturer with your vin number might be the easiest if they are still in business.


----------



## ShortBoatFishin (Mar 6, 2013)

Details of boat please. But I'd say measure the height of the transom. You should match that with the outboards shaft length.


----------



## SHO-NUFF (May 30, 2011)

Measure from top of transom, where motor will sit, to bottom of pontoon. That measurement should be same on engine from inside of engine transom mount to cavitation plate (horizontal plate above gear case) on whatever outboard you choose. 
90 percent of pontoon boats use a 20 inch shaft, like bass boats. 
There are more 25 inch outboards out there for sale, and can be used with a jack plate to get the right height. 
You can put a 25 inch shaft engine on the boat if it needs a 20 inch shaft, but it will have more foot in the water than needed, causing excessive drag and harder steering. An advantage to buying a used 20 inch engine, it most likely came off a Bass boat that spent most of its former life in fresh water.


----------

