I just picked up my new boat on Friday and broke it in today. It's a Shoalwater 14.5' cat with 70HP Yamaha. It has a 16 pitch 4 blade prop. It has a great hole shot with a fairly weak top end of 32 mph. The problem is that the tach only reads 2800 rpm at wide open (32mph). Is it possible that the Yamaha tach is not calibrated for this motor? I've never seen one that didn't hit at least 4600 rpm. I can't believe that it's a prop issue. The motor sounds like it's reving higher than the tach says and it otherwise performs normally. Thoughts anyone?