baywatch & Payton,
The reason I ask is simple, baywatch is you are serious about converting to diesel in the future I made want to help you. If you read my notes (5 pages) on the other diesel thread here you see I make refernce to a gear box. I might be willing to dust that off and make you a set of those so you can run your same bravo drives.
This is not a tomorrow thing, I need to rework the design a little, build a proto and slap it on a genset for 1,500 hrs.
Now Konrads or Arnesons??? Depends on what you want to do.
I don't know what ratios Konrads come in but here is where RIK and myself disagree. I will give him credit that his turn a big wheel slower advise is good for 99% of the boats out there. It's the little 1% of the world that I have spent years playing in.
In my experience running the diesels in open water where you had to actually throttle a boat (not just cut the engines back) when we tried big wheels, the second you move that throttle back and props loose a little bite the diesels loose boost. With the big wheels you just can't accelerate the engines quick enough to get that back and boat just flops rather than fly like a gas boat.
The bigger reduction gear also works in reverse now because of the prop drag and further holds the engine back. Here's an example when you push start a car do you use first gear or high gear? You use high gear which is less reduction, the same with a prop, the water grabs it like push starting a car in 1st gear.
Again, if you are just crusing, high speed running on the smaller lakes, bays, etc. That big prop provides good top speed, great cruise speed and great economy - RIK is right.
Run the boat from Sandy Hook to AC with a 20 knot South and wind and you'll suck wind!!
Again, my opinion alone.