Horsepower vs thrust
 

Hi,
Too many years ago I spent a month aboard one of Uncle Sam's grey
yachts, the Garcia. It was powered by what looked like a huge single
shaft electric grinder motor, complete with a round "GE" emblem about a
fathom across. The electricity was provided by gas turbine driven
generators. Electric power allowed complete and immediate control
directly from the bridge.

This, plus seeing my marina neighbor polishing his boat using power from
a portable 2KW Honda generator got me thinking. Should my ancient
Atomic-4 die, would it be feasible to replace it with a pair of
thrusters designed for maneuvering bigger boats; these driven from a BIG
battery in turn charged by a pair of these Hondas?

Trouble is, thrusters are rated in pounds of thrust and I dunno how that
relates to HP so I can't figure how much thrust it's take to push my
Catalina 30 down the bounding main at say 5 or 6 kts. Anybody know how
to relate thrust to HP? Anybody tried electric power in a medium size
sailboat?

TIA, Vito

Horsepower vs thrust
 

See also: http://www.solomontechnologies.com/

Joe Wood

wrote:
On Wed, 24 Sep 2003 12:43:13 -0400, Vito wrote:


Hi,
Too many years ago I spent a month aboard one of Uncle Sam's grey
yachts, the Garcia. It was powered by what looked like a huge single
shaft electric grinder motor, complete with a round "GE" emblem about a
fathom across. The electricity was provided by gas turbine driven
generators. Electric power allowed complete and immediate control
directly from the bridge.

This, plus seeing my marina neighbor polishing his boat using power from
a portable 2KW Honda generator got me thinking. Should my ancient
Atomic-4 die, would it be feasible to replace it with a pair of
thrusters designed for maneuvering bigger boats; these driven from a BIG
battery in turn charged by a pair of these Hondas?

Trouble is, thrusters are rated in pounds of thrust and I dunno how that
relates to HP so I can't figure how much thrust it's take to push my
Catalina 30 down the bounding main at say 5 or 6 kts. Anybody know how
to relate thrust to HP? Anybody tried electric power in a medium size
sailboat?

TIA, Vito


This should get you started...

http://www.acbs.org/Public/Rudder/Sp.../ElcoFound.htm

BB

Horsepower vs thrust
 

If you are highly motivated, you *could* try this way....

Get a friend to tow you at 5 kts on a long line with a scales
on the line, reading to say 500 lb.

Multiply the drag in hundreds of pounds times two -
that's in the ballpark for the HP you need with a reasonable
prop to make 5 kts at the attitude you were towed.

Brian Whatcott Altus OK


On Wed, 24 Sep 2003 12:43:13 -0400, Vito wrote:

Hi,
Too many years ago I spent a month aboard one of Uncle Sam's grey
yachts, the Garcia. It was powered by what looked like a huge single
shaft electric grinder motor, complete with a round "GE" emblem about a
fathom across. The electricity was provided by gas turbine driven
generators. Electric power allowed complete and immediate control
directly from the bridge.

This, plus seeing my marina neighbor polishing his boat using power from
a portable 2KW Honda generator got me thinking. Should my ancient
Atomic-4 die, would it be feasible to replace it with a pair of
thrusters designed for maneuvering bigger boats; these driven from a BIG
battery in turn charged by a pair of these Hondas?

Trouble is, thrusters are rated in pounds of thrust and I dunno how that
relates to HP so I can't figure how much thrust it's take to push my
Catalina 30 down the bounding main at say 5 or 6 kts. Anybody know how
to relate thrust to HP? Anybody tried electric power in a medium size
sailboat?

TIA, Vito

Horsepower vs thrust -- Thanks all
 

Thanks for the info.