Pedal power???

Foredeck Shuffle

More of a Stoic Cynic, Anarchy Sounds Exhausting
My bike has toe straps and tubulars.
So does mine, triple butted chromoly frame with pencil thin tubes, oval chain ring, 18 speeds.  Was tired of doing my own work and having not serviced it in a few years, took it to the shop for new bearings.  Kid looks at the bike, then me, then the bike and says, "Do you have a leather helmet and shoes to go with that thing?"

 

Pertinacious Tom

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I carry my paddle on my Adventure Island. Mine's an old one, so doesn't have reverse. I use the paddle for reverse. I also use it to swat the telltales when they stick to the sail. When my rudder pins have broken in areas where I didn't feel like changing to a spare, I've used it as a rudder.

But Greg Ketterman made it obsolete as a way to move the boat by making the Mirage Drive.

What happens when an ordinary geek with a Mirage Drive takes on an Olympic medalist with a paddle? He tows that medalist backward rapidly.




 

Panoramix

Super Anarchist
2 hours ago, Pertinacious Tom said:

I carry my paddle on my Adventure Island. Mine's an old one, so doesn't have reverse. I use the paddle for reverse. I also use it to swat the telltales when they stick to the sail. When my rudder pins have broken in areas where I didn't feel like changing to a spare, I've used it as a rudder.

But Greg Ketterman made it obsolete as a way to move the boat by making the Mirage Drive.

What happens when an ordinary geek with a Mirage Drive takes on an Olympic medalist with a paddle? He tows that medalist backward rapidly.


Yes, but it is not often that you have to pull on stuff while static! Also whereas I am not really super fit I row at the same speed as a canoeist who competes at a national level (my rowing club share the same bit of river with a high level training centre for canoeists) without a super human effort.

May be I am wrong but I am not convinced that a pedal drive is more efficient than a pair of oars. Slidy seat rowing is quite good at extracting power out of a human as it mobilises many muscles efficiently.

 
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Pertinacious Tom

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Yes, but it is not often that you have to pull on stuff while static! Also whereas I am not really super fit I row at the same speed as a canoeist who competes at a national level (my rowing club share the same bit of river with a high level training centre for canoeists) without a super human effort.

May be I am wrong but I am not convinced that a pedal drive is more efficient than a pair of oars. Slidy seat rowing is quite good at extracting power out of a human as it mobilises many muscles efficiently.
He went up against a tandem kayak and towed them backward too, but not as effectively.

He did not try it against a row boat with a sliding seat. I think I'd bet on the row boat in that case too. But an oar isn't a paddle and he made the paddle obsolete.

I've paddled my Adventure Island. Even without the amas, the thing is a tank. I have kayaks that move like a kayak is supposed to do. It doesn't. BUT, with the MIrage Drive, I can pedal in company with normal paddling kayaks. I can go a lot faster for a lot longer than I can with a paddle. That's why my paddle is never used for propulsion. I tried it. It sux.

That said, I've experienced and read about various Mirage Drive failures. Never had a paddle fail.

 

bluelaser2

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Mine's an old one, so doesn't have reverse. I use the paddle for reverse.

You can just pop a standard mirage drive into the drivewell backwards, and backwards you will go.  I do it often to back out of ramps etc.  

 

fastyacht

Super Anarchist
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So, the competition shown -- a tug of war is what we call "bollard pull" or literally, how much force can you apply to a fixed bollard on the dock. This is a distinclty ifferent problem from "free steaming" and in fact if you optimise one you tend to get poor results in the other. If you optimise the "propeller" for bollard pull, you will get even more extreme results. Then again you can change the paddle too...

But the interesting fact is that the hobie mirage drive as designed will outperform paddles in both bollard and in free steaming--it is a superior solution from a human output standpoint.

Oars on the other hand are a completely different problem. There is no way a paddler can keep up with oars on an equal basis. Yes, if you look at Blackburn Challenge results (around Cape Ann race) there are some rowing craft that are slower than some paddling, but a more instructive comparison can be made between shells and "olympic" style canoes and kayaks. Unfortunately the C and K run shorter distances but you can get to the shorter sprint numbers for oars too. Oars are faster.

Why? Simple really--it is all bout the legs and big muscles. Rowing and pedaling use them. Paddling does not. Even high knee paddling uses the back but not the legs--although yes your glutes will cramp the first time you try it!

 

Pertinacious Tom

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I wouldn't be interested in a kayak drive with a propeller. I hit stuff too often and they require too much water.

A Mirage Drive requires a lot of water for a full sweep, but you can tuck the blades up against the hull and scuttle along pretty effectively. About like a kayak paddle in shallow water is "pretty effective." It's a good way to bend a Mirage Drive mast but I haven't bent one in that particular way. Yet.

 

couchsurfer

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Rocking and sculling are very effective for most small keelboats and require less equipment. One person can move a soling along very nicely with very little effort standing on the rear deck and rocking and sculling. My J70 will move along decently rocking,  sculling is less effective.
I put an oversized rudder on my US25.  I'm quite amazed at its sculling power now. Seems equivalent to a 2-3 horse motor

 

tane

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wouldn't a rower on a sliding seat beat a pedaller by a lot? on the bike one mainly used leg muscles & gluteus maximus, wheras on the sliding seat you add all the back muscles plus biceps to the same legmuscles you use on the bike (& those over their whole range of motion, wheras on the bike the legs never get fully extended nor fully "retracted"

just guessing...

 

tane

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alas, seems I guessed wrong:
chart2.jpg


 

tane

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https://www.velonews.com/news/how-olympic-rower-jason-osborne-beat-worldtour-cycling-pros/

another athlete who's power output rowing or cyling is practically the same

more musings: max power is limited by the oxygene that can be absorbed; adding more muscles to the effort only goes so far, then all those extra muscles would need more O² - which isn't coming.

BTW: hava a look:

"20-minute cycling power: ~480 watts  (6.67w/kg)"

"...in excess of 10.3w/kg in the closing 400m..."

F....G 721W for a 70kg/155,6lbs athlete

 

Marcjsmith

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wouldn't a rower on a sliding seat beat a pedaller by a lot? on the bike one mainly used leg muscles & gluteus maximus, wheras on the sliding seat you add all the back muscles plus biceps to the same legmuscles you use on the bike (& those over their whole range of motion, wheras on the bike the legs never get fully extended nor fully "retracted"

just guessing...
i would think that a prop would be more efficient at  transferring the energy to the water.  also with a rowing setup   you are wasting energy resetting the oars

 

JohnMB

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i would think that a prop would be more efficient at  transferring the energy to the water.  also with a rowing setup   you are wasting energy resetting the oars
Rowing is surprisingly efficient; at speed the losses in resetting the oars are tiny. The biggest losses are in the water, and there a well placed oar blade will beat a prop every time. There should be almost no 'slippage' of the blade in the water at steady state,  and the oarsman can 'tune' their stroke to match the speed of the boat, with a prop you are always not quite in the perfect speed range, and even there the losses are significant.

Some guys at cornell did a study....

 
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Marcjsmith

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The biggest losses are in the water, and there a well placed oar blade will beat a prop every time. There should be almost no 'slippage' of the blade in the water at steady state,  and the oarsman can 'tune' their stroke to match the speed of the boat, with a prop you are always not quite in the perfect speed range, and even there the losses are significant.
thinking about a rowing chair, on a sail boat, where the person rowing probably isn't the kind of oarsman who can tune their sweep...

 

longy

Overlord of Anarchy
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The Hobie drive is 'continuous' power - there is very little time spent in the blade reversing stage. Oars/paddles, however, have about a 50/50 pattern of power vs re-set(no power)

 

bluelaser2

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I'm far from an athlete and 54 years old, but 180 watts for 30 minutes on a rower is about all I can take.  I can push 200+ on a bicycle for an hour without too much discomfort.   Point being: if your body is not pre-optimized for either sport, pedaling will probably produce more power for longer v. rowing or paddling.  

 
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tane

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a disadvantage of the rowing must be the pronounced "pulsing" of the power with commensurate ac- & deceleration. Pedalling, the powerpulses are much less pronounced.

more musings about the limit of the output being determined bei max. O² absorption, no so much (within reason) by the numbers of contributing muscles:

cycling I notice distinctly, that standing up in the pedals when climbing steeply doesn't make me any faster over a distance longer than say 50m. The numbers of muscles contributing  increases quite a bit, but as I am at max O² anyway the additional "push" only lasts 10sec. or so.

(BTW: seeing all those Watts here again confirms, that one's attainable limits are extremely predetermined by genetics. Killing myself in training & dieting I will still never attain 200W steady for 1/2h, & not because I'm 66 now; would have been the same 25 years ago...)

 

Gouvernail

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Most of the reason I rarely use a motor in n a sailboat has to do with two things;

* I thoroughly enjoy trying to figure out where the wind is coming from when there is so little it is difficult to tell

* there is never any hurry to get back to the dock because I would rather be sailing than on shore

++++++++
I pity those whose priorities are so screwed Up they have convinced themselves it is ok to have  obligations whose servicing interferes with sailing. 
 

47 years ago we scheduled our wedding on a weekend when there were no nearby regattas scheduled. What kind of inconsiderate must a son or daughter be to schedule a wedding on a day when the parents would otherwise be sailing?? 

 

Panoramix

Super Anarchist
https://www.velonews.com/news/how-olympic-rower-jason-osborne-beat-worldtour-cycling-pros/

another athlete who's power output rowing or cyling is practically the same

more musings: max power is limited by the oxygene that can be absorbed; adding more muscles to the effort only goes so far, then all those extra muscles would need more O² - which isn't coming.

BTW: hava a look:

"20-minute cycling power: ~480 watts  (6.67w/kg)"

"...in excess of 10.3w/kg in the closing 400m..."

F....G 721W for a 70kg/155,6lbs athlete
Yes, that sounds logical whether on a bike or in a rowing boat, fitness rather than raw power for any effort lasting more than 30 seconds will be my limit. In the pedal drive, there are cogs which will eat power and the area of the propeller will be much smaller than the oar blades area which implies more slippage, but that is just "gut feeling".

I actually want to know, if I had access to pedal power, I would try as I am equally (un)fit with sameish technique level for cycling and rowing and I wonder which one would be more efficient. Ideally one would want a boat that can be fitted with either propulsion system. My instinct tells me rowing as there is a very direct connection between a reasonably good rower and the water but may be I am wrong.

 
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JohnMB

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 My instinct tells me rowing as there is a very direct connection between a reasonably good rower and the water but may be I am wrong.
This is correct, there are hundreds of papers dealing with many aspects of the rowing vs pedal question.

On efficiency there is this one:

https://www.semanticscholar.org/paper/Propulsive-Efficiency-of-Rowing-Oars-Cabrera-Ruina/c37e281e0aaddc0bcf34db0d5a9176cba1d27dd0

Of course there are some many different ways of posing the question. This only looks at the efficiency of the power transfer. Other papers show that the rowing action itself is less efficient than pedaling, in terms of available human output power. Also it will be very different if you are considering steady state vs acceleration, and working at UT1(low aerobic) say vs at AT(Aerobic threshold).

The whole story requires that all these different things are put together.

 


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