That analyzer kinda sucks. Try going to www.go-fast.com .
Look under knowledge base,speed calculator. I have found this to be very close to real world. You must be fairly accurate about the REAL weight of your boat. I generally add 1000 lbs to the factory number for gas,gear and bodies.

I tried it and it was 8mph fast. I dont understand how you can accurately judge speed using HP and weight. Knowing how many rpm's you can turn an inch/pitch prop makes more sense.

Something else to figure in the
calculations.....Bravo style props
are said to be about 1.5" over rated
compared to other styles.

I don't see how using weight and horsepower on a boat can be near as accurate as rpm's and pitch. It leaves way to many variables, where rpm and pitch are real numbers. On a car it is possible to get fairly accurate acceleration numbers since most cars roll with (about) the same resistance.