Which prop did you calculate the slippage on? They are diff. pitch aren't they??

Just a curious question ,do both shafts spin the same speed.

Why did anyone ever put a Bravo 3 on a 20' Cigarette??!? Completely inappropriate.

A Bravo 1 is a far obviously better choice with a nice Mirage Plus prop for a try.

Exactly what I was thinking!!!!

Yes, they do. As to the staggard pitch, I really don't know. It's not unheard of though. When the pitches are staggered, then you average the two. As to a V-bottom having 6% slip, that's not really feasible with your performance numbers. Something is in error there.

Huh? I think you meant the uppers are similar. The lowers are completely different.

I think VP Duoprop uses a diferent pitch but BIII does not.

I also agree, something isn't right with the prop slip. Although my boat isn't near the same as a 20' Cig hull, mines more like a 24' bath tub, I have labbed and cupped 26p props. According to Winprop mine has about 11-12% slip. Adding cup and labbing made a big difference. BIII props are notorious for being very imbalanced. Mine was much smoother, and of course bit the water quicker making it more responsive.

The amount of cup added was about the equivalant of a 27p. I think generaly with a BIII, labbing will gain aout 200-300 RPM then you add a little cup to bring it back down and you have 2-4 MPH gain plus it's a whole lot smoother! The motor and drive MUST love that!

I'm speaking of the overall shape........as far as a hydrodynamic comparison.

the B3 has far less prop slip than the B1, so your mid range numbers would much better.
Better fuel economy, lower rpm/mph. You may loose some top end, but to me I would rather have better mid range numbers.

The front prop is larger in diameter than the rear, but the same pitch, The Volvo has different pitches.

Unless you have a HEEEAVY 20 footer I still think you'd be more efficient running a B1 with a 4 or 5 blade for midrange and takeoff and not hurt your top speed with the B3.