I have a 1981 17' Starfire Skeeter bass boat, and a 115hp Johnson V4 outboard on it. I just rebuild it and it has good compression and seems to run fine on the lake except one thing! I cant get the boat to go faster than 40mph!<br /> <br />Everyone says that it should do at least 50, and I have talked with a guy that said he had one and it did 55. Right now I have a 13 3/8 X 17p Stainless prop on it. I get it on plane real nice but then when I trim it up the rpms go way up to 6500! So I cant trim it up when running WOT. So I bought a 13X19p aluminum prop and tried that, it seemed to plane out a little slower but the top end was still 40mph and my max rpm dropped down to 5800. So I went and borrowed a 4 blade 12 3/4 X 21p SS prop and it cause me to have terrible holeshot and still I could only get 40mph out of it. But with the 4 blades it did drop my rpm down to 5500 rpms.<br /><br />This motor has a hydrofoil on it and like I said seems to run good but I just cant figure out how to get the boat passed 40mph. I've talked with the local marinas and they reluctantly gave me advice to buy a new 450$ prop!<br /><br />I told them i'm not buying any more props until I can find out what is the reason for my slow boat.<br /><br />Could it be my hydrofoil? Could it be my boat is set down in the water too far? Or could it be I need a jackplate? Can I move the motor up even if I dont have a jackplate to see if it helps?<br /><br />Any help I would really appreciate =), thanks<br />Koltar