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R.W. Behan
 
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Default transmission in reverse during sailing


"John R Weiss" wrote in message
news:cjcVa.168299$H17.60017@sccrnsc02...
"R.W. Behan" wrote...

Can't tell you why your transmission is getting stuck in reverse, but I
would heartily recommend PUTTING it in reverse while you're sailing.

That
isn't boat-specific, it is common-sense specific. An auto-rotating

prop,
whether on an airplane or a boat, creates drag that is equivalent to

towing
a disk of the prop's diameter, and that's a LOT of drag. When you

"freeze"
the prop by shifting to reverse (the equivalent of feathering an

airplane's
propeller) you lower the drag to what is caused by the area of the

prop's
blades--probably a third or so of the area of the prop's diameter.


Not quite...

Feathering an airplane's prop also includes turning the blades within the

hub so
they are faired into the air stream, more like the folding/feathering

props
available (at high cost) for sailboats. Simply stopping the prop will

slightly
reduce drag, compared with autorotation, but will not reduce it anywhere

near
that of a feathered prop. There is still the turbulence created by the

unfaired
blades, and that creates drag.


John, you're dead right. My statement was a bit ambiguous. By "equivalent"
I meant that feathering and shifting to reverse are "equivalent" in terms of
stopping the autorotation. They are not equivalent in terms of reducing
drag.


OTOH, putting the prop in gear may reduce wear on the transmission, shaft

seal,
and cutless bearing...



Yep, and that's reason enough, right?

Cheers,

Dick


 
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