Borg Warner Velvet Drives are hydraulically operated by the boats engine
turning a gear
pump. While the BW manual states that "windmilling" is acceptable while under sail or on twin engine fishing
vessels, there is wear. Some of the bearings depend on the pressurized oil
for lubrication, plus you have more moving parts
like your shaft, the cutless bearing, and stuffing box.
I have been rebuilding BW Velvet Drives for over 40 years and have seen the damage caused by not locking your shaft. Continue long term windmilling and you will pay
. I recently rebuilt a gear box like yours $850USD + a bottle of Talisker.
There are several shaft locks on the market for hydraulic gear boxes. If you intend to continue anchoring
and/or sailing with your engine off, lock the shaft. I have a Luke feathering prop on my boat, so when we sail, I have the Commodore bring the boat up into the wind
until the prop stops spinning, then I grab the shaft with a heavy leather glove, stop it, and attach a pair of "Vise Grip" pliers to a bolt on the output shaft coupling. In case of emergency
or forgetfullness, I have a short lanyard attached to the pliers, so if I must start the engine they will not launch.
This has worked for me for 29 years. Your mileage may vary. Be careful.