I am contemplating a repower with either a Beta 35 or a Beta 43. I have no interest in the top end rpms of the Beta 38. I have been reading Dave Gerr's book on propellers. He says the MINIMUM diameter propeller for a vessel of Morgan 382 proportions is 18" We all have 16" wheels. Keefer Douglas tried 17 and 18' wheels and rejected them because of high cavitation. The Brewer "owner plans" show an aperture of 21" in height and a prop drawn to be 18." Does someone have available an actual measurement of the aperture? Thanks. I will try looking in archives, as well.