Anyone with BMax Drives? - Page 2

PatriYacht · 06-21-2006, 03:34 PM

Spinning the prop faster with the 1.30 ratio would cause more drag on the prop blades. The 1.5 ratio in a Bravo is thought to be more eficient up to about a 32 pitch prop. Only go to the higher ratio when you run out of prop pitch or when you want to reduce stress on the lower. Of course all boats react differently.

LiveWire · 06-22-2006, 02:23 PM

What about leaving the gear ratio alone - like a lot of you have said and going to a 5 blade prop? This is some of the response I got from another thread I have going. If this is true then which 5 blade and what pitch should I start my test with?

zt260 · 06-22-2006, 03:18 PM

Quote:

Originally Posted by alamping

What about leaving the gear ratio alone - like a lot of you have said and going to a 5 blade prop? This is some of the response I got from another thread I have going. If this is true then which 5 blade and what pitch should I start my test with?

What is your WOT speed (GPS), RPM, and prop?
If you go to shortys the 5 blade will help otherwise they will slow you down.

PatriYacht · 06-22-2006, 03:39 PM

Were the boxes from the factory or were they added later? If they were added, did you raise the drive height? There might be a little more speed there if you went to -2" shorty's and 5 blades.

LiveWire · 06-22-2006, 04:37 PM

zt260 here is your answer: WOT 83/84mph on GPS at about 5400rpm spinning 28P Bravo 4 Blade. This is two guys and 2/3 tank in glass to 1ft chop.

The boxes are Warrlock and were installed at the factory. Original drives were Mercury XR if I recall and then switched to the BMax which had the same X Dimension and those were installed by BMax themselves (Donzi and BMax are close to each other) which made things easier. I just know I'm not getting the full use of my power.

zt260 · 06-22-2006, 04:55 PM

Measure the propshaft up to the hull. How deep is it in the water? If your say 5"+ deep the following should work.

If you get shorty housings swap everything over and 26" maximus props. You should gain some speed. I gained 7mph after this swap and some lab finishing by BBlades.

LiveWire · 06-22-2006, 05:22 PM

I'll get back to you after I get the measurement. Just to make sure I measure it right. With the drive level - do I extend a horizantal line to the bottom of the Hull where the prop shaft would run if it could reach the transom (Not to the bottom of the V)?

zt260 · 06-22-2006, 11:13 PM

Yes run an invisible line from the propshaft back to the hull where it meets even with the hull. (Not the bottom most point in the center) I know it is hard with twins, but it is necessary to give you good advice.