could someone please explain to me what pitch prop i need and how you work out which prop i need to get my boat to go faster without reving the nuts out of the engine too much? (simply as this is all to confusing for me)I have a 1981 evinrude 60 hp engine model No# E60ELCIA serial No# B010892 Oh and with gullwings, on a 15.5ft glaston speed boat with a small home made cuddy on the front. she is only getting 27knots she would get 22 knots with my old 30hp mariner but that i was told was a 6pitch prop and the engine was screaming but run very well doing so this all makes no sense to me as i have been told so many different things, many thank to anyone how can help, Tony