I got my 90 31-2 hull 252 with a 2 blade 16x11 on it. I put on at the suggestion of Campbell Props, the prop manufacturer, a 3 blade bronze 14x8. They both gave me the same performance at the same RPMs...nice cruising speed of 6k at 2200 in calm waters, but anything over 2400 would cause black smoke, and can never get higher than 2600 RPMs anyway, unless in neutral, then all the way to 3500. So when I'm knocking back the waves, I can get put back pretty good, even all the way once to 0k in a 40k headwind once. The one big difference though I found with the 3 blade was much less power in reverse, but as promised, my prop walk is very minimal, and less vibration. I'm wondering myself what I should do to achieve higher working RPMs with no black smoke?
