swan2

Can someone please explain why the BravoIII is not a good drive for high speeds???? Im talking 70 plus in speeds. Thanks guys in advance.

mr3dman

because it wasn't made for it. too low in the water etc....

swan2

Oh ok thanks.

articfriends

iTrader: (1)

I have heard that they don't work on "fast" boats too, is it because the props start screwing up the boats handling? The OP has told me previously his boat runs almost 80 and even after adding twin ram external it chinewalks out of control, I haven't heard much about B3's running them speeds, I would expect that having a double set of props on one drive would do all kinds of evil shiit to the handling at higher speeds , Smitty

apollard

The blackhawk ran two props and it reportedly handled well. However, it was a surfacing drive, so 2x the prop drag wasn't an issue.
The BIII is designed for lower speeds so is deeper in the water and has a larger lower unit case (derived from the BII case, IIRC). So, more drag on the lower unit as well as prop drag. At lower speeds (<65 from my research) the dual props low slip overcomes the drag easily. For example, at 57 mph, my prop slip is ~6%. At higher speeds, the drags goes up - fast. Drag goes up exponentially with higher speeds.

swan2

I am assuming these props have to be clocked on the bravo III?? Maybe when the front prop blade is at the top the back prop blade is at the bottom I assume??? If so mine was off one or two splines. Could this have be causing some handling problems like the chine walking or does this being off really not have anything to do with it??

Knot 4 Me

I doubt clocking them properly will make any difference in handling at speed. I also have never found where Merc talks about clocking BIII props (I'm sure it must exist), only Blackhawk props. But the Blackhawk prop clocking procedure is what everyone uses to clock the BIII props.