Paul I. wrote:
The big difference between the 2 drives are, or at least to me.
On the alpha, the raw water impeller is built into the drive. So you need to split the drive to get at it. On the B3, its on the engine. So the boat can remain in the water and its much easier for you to do. Also cheaper if you want the dealer to do it.
The B3 has 2 counter rotating props on it. Which takes out what some boaters call "prop walk". So in docking or slow speeds, the boat will go were ever you point it. Not so on a Alpha.
The Alpha uses a AL prop were the B3 uses a S.S. prop. So the B3 will give you better MPG and better all around performance. BUT the AL prop will bend over fast & easier if you hit something. Were the S.S. prop is harder and send more of the shock into the drive.
If it was me, I would go with the B3!
Paul,
I respectfully disagree with you on a few of your major points....
The Alpha impeller is much easier to change...but only if trailered! (the only gripe I have about the B1)
For me, I prefer "prop-walk" when docking; it allows me to move the boat side-ways up to the dock. (personal preference)
Al vs SS.... you are allowed, and IMO encouraged to use an SS on Alpha, or B1 drives. We have beat the whole argument to death on that, so I wont go there.
The B3 will give you LOWER MPG and LOWER TOP END, as you are turning twice as much gearing, and have twice as much drag (2 propellers) in the water. As pointed out in my previous, you get about the same hole-shot and top end as a lower pitch 5 blade prop on a B1 compared to a VP DP (and likely similar for B3 with same gear ratio)
From an ease of maint perspective, I recommend the B1 drive... it's rated to something like 600 HP and 100 MPH (alpha is rated to 300 HP), remove the prop to change the drive oil; but the impeller is underneath the engine.... at least Volvo did that part right (front of engine).
_________________
Walt B
"Debt-Charged"Black '07 H210SS6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.