what shaft length do i need

[reynold460]

hey guys my boat has a transom height of 21 inches from top to bottom does that mean i need a 20 inch shaft motor or do i need a 25 i have a 115 mariner on boat now but dont know how to measure how long of shaft it is the serial of old motor is 6527845 is there a way of telling what shaft length a motor is by the serial number

 

[JB]

Re: what shaft length do i need

Shaft length is measured from the underside of the transom clamp to the anti-ventilation plate. Yes, you need a long (20") shaft.

 

[Mi duckdown]

Re: what shaft length do i need

+ 1

 

[reynold460]

Re: what shaft length do i need

ok i need a 20 inch shaft would it be possible to use a 25 inch shaft instead and what would be the problems if i did use a 25 inch motor thanks in advance

 

[Mi duckdown]

Re: what shaft length do i need

You will have 5" to much motor in the water. They say, for every inch, you will lose 1.3 MPH. which also leads GPH. Plus handling and Planning

 

[reynold460]

Re: what shaft length do i need

ok thanks alot . great info from knowledgeable people