Velvet Drives:Why a 2” drop on port , straight on starboard?

[Billywilly]

Why, in our 1984 Mainship double cabin forty, would there be a drop transmission (2” from engine input to shaft output) on port side (10-14-000-003)) and a straight thru drive (1018-106 rebuild by MTS) on starboard? Velvet drives on Perkins T6.3544M’s.
Have no history and just discovered after seven years of ownership. Duh.
Appreciate any feedback, ideas.
Thanks

Bill

 

[KnotYet]

Greetings, Billywilly. To allow counter-rotation?

 

[rgano]

It would appear to me on first blush that your boat was originally equipped with twin "drop center" Velvet Drives and that because the drop center drives are a known "maintenance issue" with near unobtainium parts supply as compared to the straight-through models, somebody substituted a straight through model when the starboard D-C tranny died.

I had the straight through models on my twin diesel trawler, and to allow counter rotation, because they all used the same outer ring gear, an extra planetary gear was added. My two cases looked identical except that the cooled tranny fluid from the cooler was dumped back into the case directly over the planetaries on the side with the extra one to help cool it better. Probably the same was done with the drop center models.

If I am correct, and no changes were made to the stbd shaft log, your stbd engine is mounted higher than the port.

 

[Billywilly]

Gentlemen,
Thanks for your replies.
Both make perfect sense to me.
I’ll be measuring tomorrow.
Regards
Billywilly