Paddleducks
Old Yahoo Group => Yahoo Messages => Topic started by: vawarner on June 14, 2005, 06:36:08 PM
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I have a question for those who know paddle boats better then I. I
have a ship that has a total dipalcement of 550 tons and an net
dispalcement of 250 tons it has a 70NHP engine. So can the speed of
the ship be estimated? Im looking for a rough estimate.
regards
William Warner
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Hi William,
I am not an engineer by any means but have engineered
many things in my life. (hot rods,models etc.) I would
suspect that you are missing several items in your
equation. The first being the diameter of the wheel
itself. The larger the diameter the more power it
takes to turn it. The leverage principle. The next two
are the width of the buckets (paddles) and the number
of buckets on the wheel. Anything that adds resistance
to the rotation of the wheel is going to take more
power to move. There is one more thing that just came
to mind as I am writing this and that is the shape of
the hull. Here again if it is a scow type (blunt end)
it's going to take more to push it through the water
than say a curved bow. I hope this gives you a little
more to work with.
George
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William - I've just looked up my 1972 edition of Heat Engines & Applied
Heat - alas to no avail
One point we do believe is the old term of "nominal HP" ratings for paddlers
appeared rather conservative and was based on dimensions of the piston &
stroke, but should not be confused with "indicated HP" which is calculable -
appears that people rated engines as distinct to a system (boiler,
condenser, economiser & engine etc) that would produce & maintain xyz
indicated HP
From my book on (Australian) "Ships of the Inland Rivers" - it appears that
PS Mannum came in as the heavy weight at 366 gross and 202 net
(135'x32'x8'.6") - in 1884 she was rated at 7 1/2 knots from her 200IHP
About six months ago we had an interesting posting in paddleducks re speeds
of many American paddlers -might be worth going back & finding it
regards Derek