please help, prop trouble
 

hi, i successfully converted my 12 jon to a inboard using a 18 hp
b&s boxer engine, runs fine but will not plane, prop is a 7"
7pitch, no room for larger diameter, thinking maybe a 7" with a 9 or
10 pitch(possibly 4 blades or cupped) but don't know where to find,
please help. p.s. 1/2 shaft with pin and lock nut,