Propeller options

[Kahuna]

PHNX,
The boat currently has a 13.75 x 21. Too much wheel. Need to drop down to get RPM's up. I'm going to have to go with the assumption that the gear is stock on the 1984 apha 1 drive. Agree, the number on the GPS is over the bottom, and not through the water. However in about 8' of water over a sandy bottom, with minimal tide effect, minimal wind, using a Tempo tachometer, the motor turns 3850 and the hull runs just short of 31knots trimmed properly just short of porpoising. Short of wind tunnel testing, or radar gun and putting a calibrated electronic tacometer directly on the motor, I feel the numbers I have got are close enough be able to make reasonable assumptions. I would like to go to a smaller wheel so that I'm turning 4500-4600 wfo with a light load. I spoke with a dealer adn found out that a 13.75 x 19 is not availabel. I don't have the available sizes for the alpha 1 in front of me here (think I left them at the office in Newport), but if I remember correctly, every time they drop two inches of pitch, they changed an inch in diameter. So the trick here I guess is going to be to try to guess right. The dealer did also say that I could take one, try it and as long as I didn't ding it up, I could bring it back, to ensure that I get the right one.