There is really no way for anyone to know unless they have the exact same boat and motor. And then it would still depend on the weight and distribution of the load.
Theoretically, it would be the 12.5, if it allowed the motor to reach max rpm, 5000 rpm or more.
Thanks.
I dont think it is reaching max RPM. I am going to put a Tach on it and find out. There was a broken 11-1/2 in the boat when I got it and a 12-1/2 on the motor. I suspect the 11-1/2 was the original.
