I have a 1996 20ft Proline WAC with a 1996 Johnson carbed 150 Ocean Runner. Both are new to me. The hull weighs 2500lbs. It looks like it might be the original prop and if I am reading the numbers right, it is a 15 1/4 x 15. My issue is this: with only 2 of us on the boat, trimmed up, and 30...