Reduction ratio - MSB & V Drive

[S/V Ethan Grey]

Okay, I’m confused, which doesn’t take much. I am getting a new propeller, which requires I enter in the engine max power, RPM, and the reduction ratio.

For the Volvo MD7A with the MSB and Walter V-drive (standard setup), the MSB has a 1.91:1 reduction and then the v-drive has 2-1 ratio stamped on it. Does that give me an overall gear reduction of 3.82:1? Do I consider the V-Drive, or just the MSB?

[S/V Ethan Grey]

I posted this same question on the FB group and the answer I got was that the reduction gear in the MSB is removed to add the Walter V-Drive. This makes sense to me since the MSB rebuild manual states it is a 1:1 and there is an alternate version with a 1.91:1 ratio. I don’t know if this will make any difference when they figure out what size prop I need, but it’s good to know nonetheless.