I don't know Alabama at all, but perhaps I can shed some light:

Great Britain (first iron screw steamship, launched in Bristol, 1843, now
back in Bristol, see http://www.ss-great-britain.com/) was refitted in 1857
for the Australian trade, which required that she sail well. To accomplish
this she had a lifting screw. Perhaps Glenn should consider this for Rutu
instead of a MaxProp.

Take a propeller with a stub shaft, fore and aft. Put bearings on both
ends and a square on the forward end. Hang the bearings on a frame that can
be lifted straight up in channels.

In order to raise the propeller for sailing, you:
1) remove a short section of shaft inside the vessel.
2) slide the tailshaft forward
3) raise the frame with tackle.

To operate under power, it's the reverse, except that when sliding the
tailshaft aft, you have to engage the square on the stub shaft in a hollow
on the end of the tailshaft.

That's how it's described in the text of The Story of Brunel's SS Great
Britain, Ewan Corlett, Conway Maritime, 1990. However, a drawing by Basil
Greenhill in the same book shows a dog clutch rather than the square.

The Great Britain museum is a wonderful view into the first large ocean
going screw vessel -- it's a great story, as she was rescued from the
Falkland Islands where she rusted from 1886 until 1970.


--
Jim Woodward
www.mvFintry.com


..
"BF" wrote in message
...
"Glenn Ashmore" wrote in message
news:ghSqb.10765$62.10532@lakeread04...


Jim Woodward wrote:

Interesting. It's amazing to watch a vessel equipped with a VS
drive --
they really can go in any direction with full thrust.

I'd worry about efficiency -- the end plate is a larger problem in a
small
one than in a large one, a VS is not as efficient as a propeller, and
you'd
probably have to go diesel electric or diesel hydraulic in order to
retract
it, and both are lossy.

Do you know what it costs?

That's why I said it was not ready for prime time. It would be fun to
dock though. Especially with a retractable bow thruster. A pas de
bouree up to the end of the pier and with a quick piorette and a short
petit jete you are into your slip. (Tutus and leotards optional)

The web site said to contact about prices and if it were objectionable
they would let you know when the production gets above 10 in a batch.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com


Changing the subject totally:
Raphael Semmes, in his account of the CSS Alabama, mentions on several
occasions of fitting the propeller (maybe he used the word screw, not
sure)
before making steam.
Anyone have a clue what he meant.
Did they actually remove the screw and shaft when sailing. If so, how,
without stopping and sending divers down, which they obviously didn't do.
Or did they simply disengage the screw from the drive shaft so it free
wheeled, and then needed to reattach, perhaps lacking a clutching means?
Or did the shaft pivot on a u-joint near the packing gland and could be
pivoted so the screw was above the water line?
Anyone know or have other ideas?
Anyone else care?
Ray
(btw, I will definitely try Duke's in Ridgeway this Spring when in
Charleston, hope a good thing isn't being spoiled here. Can you say Wreck)