Automatic Freewheeling gearbox?

[BobT]

Can anyone identify the gearbox behind the transmission? This is in my new old ('79) Gulfstar 37. All historical data is no longer pertinent as the boat was repowered with a Yanmar 4JH4E about 7 years ago. The prop shaft spins under sail no matter what the shift lever is set for. That's ok with me for the reduced drag.
This box also apparently reverses the rotation. According to the engine data, it's Right-handed. The prop is L.H.
It all works fine. It would be good to know what's there when it decides to do otherwise...

Thanks,

Bob

 

[BobT]

It's looking like a Velvetdrive, but getting a peek at any number plate is pretty challenging if it's on the port side.
Do these transmissions freewheel normally?

 

[oldersalt]

I believe most VelvetDrives are supposed to be left in neutral when the engine is off, so the prop will freewheel. As I recall, you can damage the VelvetDrives hydraulics be leaving it in either forward or reverse when the engine is off.

 

[BobT]

Thanks for the tip.

 

[kloudie1]

Found this at the Gulfstar Owner's Club site. Probably not your exact model but it looks like they kept the Velvetdrive transmission when they re-powered. Very complex compared to a "normal" marine gear, but pretty straightforward. Like a one gear auotomatic transmission using no torque converter.
http://www.gulfstarownersclub.com/library/VelvetDriveServiceManual.pdf

 

[BobT]

Excellent. I'll crawl down there again and find the name plate. And the dipstick! Very cramped on the port side...
Many thanks.