Transom Height to Motor Shaft Length

[Brad S]

I havea 16' Valco Bayrunner, the transom was notched out +7", it appears the original transom was very close to 25". The cut out area was very poorly done. I am proably going to restore the transom to its original height.
Am I going to have to use a 25" shaft motor or can I use a 20" shaft?
There seems to be more 20" shaft motors available in my area.

 

[88BLiner]

Re: Transom Height to Motor Shaft Length

From what I have read the cavitation plate should be at or within 2 or 3 inches of the bottom of the boat. Just make sure the water intake will be under water.

 

[sschefer]

Re: Transom Height to Motor Shaft Length

I havea 16' Valco Bayrunner, the transom was notched out +7", it appears the original transom was very close to 25". The cut out area was very poorly done. I am proably going to restore the transom to its original height.
Am I going to have to use a 25" shaft motor or can I use a 20" shaft?
There seems to be more 20" shaft motors available in my area.

You can raise the transom and still use a 20" engine but it will require the use of a Jack Plate. The good ones run between 400.00 - 1000.00. The one I use is the CMC PL65 w/gauge.
The jack plate will allow you to mount the engine at the original height and the offset will keep your cables from binding. Unless you go all out like me you should be able to do it for less than the price difference between a 20" and 25" engine.