Run Bravo 3 Drive with only 1 prop?


P

PJ

Member
I have often wondered what the results would be running only the larger, forward prop on a B3. Would it revert to behaving more like a Bravo 1 drive? ie less hole shot but higher rpms due to reduced drag and rotating mass? Possibly cause damage with the outer shaft just spinning along for the ride? It would be cool to be able to remove the 26p dual props and replace with single 28p for more speed. Obvious answer would be to just do it and see. Just never seems to be a good time to risk having to return to the launch to put the outer one back on if it doesn?t pan out.
Has anyone tried this?
Is it a dumb idea?
 
I think if you really want to do that, you'd be much farther ahead selling good condition used B3 lower units and bolting on B1 lowers.
What boat is this on? Single, twins?
 
PJ said:
I have often wondered what the results would be running only the larger, forward prop on a B3. Would it revert to behaving more like a Bravo 1 drive? ie less hole shot but higher rpms due to reduced drag and rotating mass? Possibly cause damage with the outer shaft just spinning along for the ride? It would be cool to be able to remove the 26p dual props and replace with single 28p for more speed. Obvious answer would be to just do it and see. Just never seems to be a good time to risk having to return to the launch to put the outer one back on if it doesn?t pan out.
Has anyone tried this?
Is it a dumb idea?
Click to expand...

Unless your approaching 90mph the B3 is not limiting you. While the B3 has more drag it has less slip. The B1 has less drag but more slip.

Don't remember what boat, but if you supply
WOT rpm, speed (gps) and drive ratio we can figure what might be the issue

Also removing one prop, may hurt the drive, may not, and know of no one which did it on purpose
 
Its a 260ss single engine 502 Mag B3.
Apologize I should have been more clear with respect to my post/question which admittedly is a bit fringe. Let me try. First, I am perfectly happy with the Bravo 3 drive as-is and the boat runs great with the 26p dual propset. 54mph top speed on gps @ 5400 rpms. Planes effortlessly and runs great. Life is good. I realize true high performance boating is not the realm of dual prop drives. I always hear low to mid sixties as the practical limit on the B3 but thats a different discussion.
I asked more as a what- if and had anyone actually tried it because yes in discussions of the B3, pros and cons, one of the cons typically brought up is the added drag of extra gears and rotating mass limiting top speed.

My what-if question was if anyone else had considered the possibility of removing one prop and upping the pitch of the remaining prop to somewhat emulate a Bravo 1 if only as a temporary change, say today Im going out alone and want to sacrafice hole shot and handling to gain a few mph top end.
-Would there be any top end speed gain assuming the single prop sized to maintain wot rpms.
-Would this damage or increase wear on the drive.
I suppose has to be attempted to find out. Can?t imagine I?m the only person who wondered if its doable. Never mind practical or advisable [emoji16][emoji481]
 
If your tach is accurate then your at 18%, if its actually 5200 then its 15%, even better

I think if you went with a B1 your top end would be reduced as well as hole shot. Your boat is just heavy

There is a guy on OSO goes by NoCoast (Bruce) and he has been using B3's on many high speed boats and this is where the 90mph comment comes from. Most that discuss the B3 use info from others and all good. The B3's Bruce does also have props tuned so there a bit thinner which reduces the drag


My 10K lb single 27PC max is 49mph using the same props, and I'm at 23%
The 27PC with twin 5.7 has more top end then I do and that's with 2 sets of B3 drives
 
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