Stephen Baker ) writes:
William Watt says:

no moreso than paddling kills your arms.

Not so - paddling kayak-wise uses a full movement of the arms, ending with the
paddle being withdrawn and the other arm starting to work. No jarring.
Having a blade come out of the water while still under full power, then (say)
half a revolution until the other blade hits is going to be..... hmmmm -
looks for marine analogy.... like NOT having a throttle-man on an offshore
powerboat. The prop will come back into the water after a jump with the engine
spinning maddly, suddenly get loaded and break the shaft/blade whichever. Not
good. ;-(

I'm not actually looking for a continous kayak-style power, but a
discontinuous canoe-style or a discontintuous oar-stlye power. I've seen
foot-operated oars in a film on Southeast Asia.

I'm not looking at a bunch of little blades churning up the surface, but
two larger blades deeper in the water like on a canoe. I want the boat to
go smoothly and silently like a canoe, not making a lot of noise like the
peddal paddle boats I've seen. A slower action with larger, deeper blades.
Low rpm's, larger blades, more effective power.

I don't think the kids peddal shaft allows enough piston action in the
legs to work the large paddles.



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Hobie Cat makes a pedal system for their kayaks that is like a set of wings
flapping under the boat. I've never tried it myself but it looks like an
interesting idea.

http://www.hobiecat.com/kayaking/index.html

- Scott

"Bob La Londe" wrote in message
...
I have wondered about the efficiency of peddle power.

Glen-L has a nice design for a peddle powered boat, and there are numerous
peddle powere ABS plastic boats available for sale at moderate prices both
on-line and in the local big box stores.

They all have one thing in common. They use a paddle wheel for
propulsion.
I can see the obvious simplicity in design. A chain from the pedals to
the
drive axle and its ready to go. In almost all other craft though a
propeller desing seems to be more efficient.

From big ships to small pleasure craft the propellor seems to be the rule.
For a small peddle powered craft would a prop design make the best use of
the available power as well? How in the world woudl you go abotu figuring
out the optimum size and pitch prop for an application like that?

(William R. Watt) wrote in message ...
Stephen Baker ) writes:
William Watt says:

no moreso than paddling kills your arms.

Not so - paddling kayak-wise uses a full movement of the arms, ending with the
paddle being withdrawn and the other arm starting to work. No jarring.
Having a blade come out of the water while still under full power, then (say)
half a revolution until the other blade hits is going to be..... hmmmm -
looks for marine analogy.... like NOT having a throttle-man on an offshore
powerboat. The prop will come back into the water after a jump with the engine
spinning maddly, suddenly get loaded and break the shaft/blade whichever. Not
good. ;-(

I'm not actually looking for a continous kayak-style power, but a
discontinuous canoe-style or a discontintuous oar-stlye power. I've seen
foot-operated oars in a film on Southeast Asia.

I'm not looking at a bunch of little blades churning up the surface, but
two larger blades deeper in the water like on a canoe. I want the boat to
go smoothly and silently like a canoe, not making a lot of noise like the
peddal paddle boats I've seen. A slower action with larger, deeper blades.
Low rpm's, larger blades, more effective power.

I don't think the kids peddal shaft allows enough piston action in the
legs to work the large paddles.

I have often thought of using a track like a snowmobile that ran most
of the length of the boat, it could run under the boat and be pretty
shallow. You would have constant power, forward and reverse, and if
you kept the track under the boat, you could probably make it pretty
quiet. Also maybe using a softer material for the "paddles" you could
make it quiet too. If I were going to build it I would probably use
some sort of canvas with leather or rubber blades every 6-8 inches or
so. For a small boat, you would not need very big blades and this
could almost be done within the exterior limits of the hull itself
without even hanging out the bottom of the boat like a prop or paddle
wheel. What do you all think of that??
Scotty from SmallBoats.com

for a track system you only want it to go front to back. how do you get it
to return if its all underwater? they run snowmobiles short distances
over water but the top of the belt is above water.

if you try hinged blades you have to figure out how to get them to lie
flat on the back-to-front return trip as they will be hinged the wrong
way.

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(William R. Watt) wrote in message ...
for a track system you only want it to go front to back. how do you get it
to return if its all underwater? they run snowmobiles short distances
over water but the top of the belt is above water.

if you try hinged blades you have to figure out how to get them to lie
flat on the back-to-front return trip as they will be hinged the wrong
way.

Well, you could have the return above the waterline... Or if the
return were sealed except for the flat on the bottom, the water would
just go over the top and be expelled when the flap exposed itself
again to make the push trip the length of the boat??? Still have that
steering problem though.
Scotty

Scotty says:

Still have that
steering problem though.

One small track each side? Variable diff off the pedals controlled from a
handlebar?

Just a thought....

Steve

Backyard Renegade wrote:

(William R. Watt) wrote in message ...
for a track system you only want it to go front to back. how do you get it
to return if its all underwater? they run snowmobiles short distances
over water but the top of the belt is above water.

if you try hinged blades you have to figure out how to get them to lie
flat on the back-to-front return trip as they will be hinged the wrong
way.

Well, you could have the return above the waterline... Or if the
return were sealed except for the flat on the bottom, the water would
just go over the top and be expelled when the flap exposed itself
again to make the push trip the length of the boat??? Still have that
steering problem though.
Scotty

Use two tracks.....reverse one for tighter turns?


--
I'd rather put more life in my days than put more days in my life......

Probably more doable with wheels than tracks. In the dark recesses of
my memory I seem to recall seeing a number of vehicles (probably
prototypes) over the years that used the wheels for propulsion on water.
One had 8 wheels and was about the size of a John Deare ATV. Not fast
but versatile. Could be useful on backwaters to get to a remote fishing
hole and a lot quieter than an air boat.

Ron

Probably more doable with wheels than tracks.

a thought does strike me that if cunningly engineered suitably stupidly
outsized wheels on a stupidly light body could be used, they could provide
all the lift bouyancy required... you'd want some very efficient mudguards
though... and you'd have no problem getting over quicksand either.

Al

"Al" ) writes:

a thought does strike me that if cunningly engineered suitably stupidly
outsized wheels on a stupidly light body could be used, they could provide
all the lift bouyancy required... you'd want some very efficient mudguards
though... and you'd have no problem getting over quicksand either.

I've seen a kind of water tricycle made of three large wheels with big
treads like a farm tractor. Used to see it tied up to a houseboat on
the Rideau Canal. Probably used it to commute to shore.

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