Clean up the prop with a $2 bottle of toilet bowl cleaner when it becomes "unbearably rusty".
Also I think I wasn't clear . . . Boat manufactures have a good idea of what their boats will do with what power, but customers are a PIA when their boats don't perform as stated. It's not the manufacturers fault either . . . Riggers and customers setup the hull . . . a few hundred pounds of extra weight in the wrong place can be the difference b/w 3.4mpg and 2.8 mpg cruise. A customer that doesn't know how to trim out the boat properly won't achieve the specs . . . is that the manufacuters job to teach the dumb owner how to drive? Hell No!!
Air Density also has a big effect on power . . . so you need to make sure that the tests are done under the same conditions when comparing power. Wind, Tide, wave height, etc all effect performance numbers. There's just too many variables to control.
http://www.go-fast.com/Prop_Slip_Calculator.htm
Can you see the problem now with posting numbers now? It's much smarter for them to suggest props and power rather than provide exact numbers (which is a lose . . . lose deal for the builder). It's not that I wouldn't want that information as a customer, but I understand and respect their position for not releasing that information to the public.
Unfortunately uneducated folks making decisions from magazine performance numbers would be pissed off when the numbers don't match up.
I wonder how many Seacrafts sold in 2005, 2006, 2007, 2008. I doubt it would be enough to put together a spreadsheet with all the different power combinations, but I don't know that for sure. You'd have to follow up with each owner after the engines are broken in too. Anyway . . . It's just not worth it IMO, b/c the data would be junk.