Wayne.B wrote in
:

Propping a sailboat is always a big tradeoff between sailing
efficiency and motoring. For motoring a big 3 or 4 bladed pop is
ideal for a displacement hull but that is deadly to sailing
performance unless you got a feathering prop, and that is another
level of compromise and expense.


Lionheart's 3-bladed prop freewheels to operate the shaft alternator on its
4-108 diesel setup. For this reason, it has the "hydraulic transmission",
not the straight one. When the engine was swapped out, the transmission
was inspected but not changed to the other type. The mechanic said it
wouldn't be good to freewheel that shaft all the time, but I've forgotten
the "why" he told us. An extra 15-20A of 12V is easily worth the drag of
the turning screw.....

On Fri, 25 Feb 2005 20:23:14 -0500, Larry W4CSC
wrote:

The mechanic said it
wouldn't be good to freewheel that shaft all the time, but I've forgotten
the "why" he told us.

============================================

The reason is that the tranny depends on being powered by the engine
to receive proper lubrication. You will definitely shorten the life
of the transmission if you allow the prop to free wheel for long
periods of time.