Long or short shaft?

[Normelkids]

I have a 70s 16’ aluminum open boat. 17” transom. What would the max motor size capability be and will a long shaft be ok? Looking to buy a Merc 15hp 20”.

 

[racerone]

Long shaft ( 20" transom ) will work.----Perhaps shim a 20" motor up 1" or so.

 

[Normelkids]

Good idea. Will do. Thanks