Rowing Power ?

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Mel

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Anybody prepared to suggest what power equivalent might be obtained by sculling a boat compared to running its engine.

For example, my small yacht will do about 5 knots using a 9HP engine/propulsion.

So, if I used a single oar off the stern (assuming some expertise) what might I achieve with a suitable oar by sculling ?

How could I work this out and estimated the speed likely to be achieved ?
 
I have rowed in an eight which had high-tech instrumentation and strain guages built into the gates. We found that, for a very short distance, about 850 Watts was possible, but he weighed 95kg. My puny 70kg was capable only of 780 Watts. No way could I keep that up for more than a few tens of strokes, and to generate this power required a rating around 40 strokes per minute, but I guess the Blue-boat crews could manage it for the whole 18 minutes of their race.

In any normal craft, even with a sliding seat I think you'd be looking at more like 200 Watts. It's worth going onto the website of 'Concept 2' to look at their graph of 500m split times versus watts: http://www.concept2.co.uk/indoor-rowers/training/calculators/watts-calculator. A good pace for a fit young man to do over 2000m (not me anymore sadly) is a 500m split of 1'30", that's 480 Watts.

All this is for rowing with a sliding seat. Sculling out of the stern will be a tiny fraction of this.

PS: 1HP = 780 Watts
 
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I would imagine that there are too many variables to make arithmetic useful. From my childhood memories of watching fishermen yuloing (as we used to call it) their toshers, I would say that a speed of 2-3 knots would be as much as you would expect. Because the relation between speed and power is so non-linear, I don't know what this would equate to in hp.

I came across this bizarre snippet when looking for yulo (which also means a kinky girl). http://books.google.co.uk/books?id=...w&ved=0CEwQ6AEwCA#v=onepage&q=yuloing&f=false
 
jdc said:
I have rowed in an eight which had high-tech instrumentation and strain guages built into the gates. We found that, for a very short distance, about 850 Watts was possible, but he weighed 95kg. My puny 70kg was capable only of 780 Watts. s
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The rule of thumb I have seen is that anyone can keep of 100W of phyisical output indefinitely, a reasonably fit person can manage 200W indefinitely and an athlete can manage 400W continuously or 800W in a sprint. That accords well with your results, which is nice.
 
I can say from experience that its possible for 2 rather tired rowers, using long oars and rather poor rowlock arrangements to row a Rival 32 at 2 knots in the water for long periods. Athletes might manage more, better oar configuration might add a bit more, but be hard to imagine more than 3 knots under best conditions.
 
Mel said:
Anybody prepared to suggest what power equivalent might be obtained by sculling a boat compared to running its engine.

For example, my small yacht will do about 5 knots using a 9HP engine/propulsion.

So, if I used a single oar off the stern (assuming some expertise) what might I achieve with a suitable oar by sculling ?

How could I work this out and estimated the speed likely to be achieved ?
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There are so many variables that it is almost impossible to arrive at a useful figure.
In the dim and distant past there was a diving boat in Preston dock that was sculled over the stern. The water was calm and the boat heavy. I remember that it was possible to attain walking speed and maintain it for a while but greater speed required enormous effort. I think that in favourable conditions you could travel a considerable distance slowly but forget speed.
 
Many thanks for your input.

What I was thinking was that if I had a suitable oar on board could it be used to get to a buoy or other safe position if the engine stopped unexpectedly and also be used as an emergency rudder if needed. I sail mostly on east coast rivers so distance is not normally the issue, but getting out of a channel and manoeuvring in a current would be the likely issue.

Not decided as yet but it does seem to be a solution to providing an alternative system for both circumstances. Getting the sails up is not always the easiest nor quick option !
 
I have always fancied the idea of a gimballed emergency bicycle frame in the cockpit, with a chain drive to the propshaft. Props are much more effective than oars.

I can never understand why people row across the Atlantic when they could pedal, and use much larger muscle blocks more efficiently, AND see where they are going, all the while reading their Kindle.

Oops there goes another bank-enhancing patent :)
 
sarabande said:
I have always fancied the idea of a gimballed emergency bicycle frame in the cockpit, with a chain drive to the propshaft. Props are much more effective than oars.

I can never understand why people row across the Atlantic when they could pedal, and use much larger muscle blocks more efficiently,...
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Are you really sure about that? When rowing I use all my legs with really quite a lot of compression, and all my back and only use the arms for a little bit of the stroke. A bicycle definitely uses fewer muscles.

As for a prop being more efficient than oars, you may be right, but I haven't seen evidence or calculation one way or the other - have you?
 
Mel said:
Many thanks for your input.

What I was thinking was that if I had a suitable oar on board could it be used to get to a buoy or other safe position if the engine stopped unexpectedly and also be used as an emergency rudder if needed. I sail mostly on east coast rivers so distance is not normally the issue, but getting out of a channel and manoeuvring in a current would be the likely issue.

Not decided as yet but it does seem to be a solution to providing an alternative system for both circumstances. Getting the sails up is not always the easiest nor quick option !
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My son has an International Folk Boat.

With no gear at all on board with a very clean bottom, we just ran short of the buoy in almost dead still conditions this summer.

Instead of starting the outboard, I sculled off the stern, the distance of about 6 lengths of the boat, to the buoy at a very slow pace.

I would not want to do it against a tide, in a chop or into any breeze, but we were still impressed that we could do it at all.

S.
 
jdc said:
Are you really sure about that? When rowing I use all my legs with really quite a lot of compression, and all my back and only use the arms for a little bit of the stroke. A bicycle definitely uses fewer muscles.

As for a prop being more efficient than oars, you may be right, but I haven't seen evidence or calculation one way or the other - have you?
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It's not an axiomatic thought.

https://www.google.co.uk/search?q=p...nnel=fflb&gfe_rd=cr&ei=TuplVMS0PMHH8ge4oIKABQ

An oar blade is delivering power for about 50 to 60% of the time; a prop blade almost 100%.


Rattler vs Alecto, 1845, refers. :)
 
I've rowed the RYA's Sonatas in my youth.
I've rowed 20ft 1ton keelboats against the tide, you can get 3 knots or so through the water.

For short range mooring etc, a couple of big Canadian style paddles are good.

Don't forget the HP of an outboard is the power input to the prop, and only at optimum loading and max power rpm.

A one-HP horse used to move 70ft canal boat at about 3 knots.....

Sculling off the stern, as opposed to rowing like in a racing scull, seems very inefficient unless the boat and oar can be moved against each other.
Big oar, little boat, it can shift. But normal oar, heavy boat, very slow. But it does steer as well.
 
The paper was interesting, concluding that oars are significantly more efficient than are "good nautical propellers". That it's only for some proportion of the time is irrelevant because the energy input is a human, limited by his cardiovascular system, the time-constants of which are very long compared to the stroke rate of rowing.
 
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I've often wondered about the usefulness of a scull to suit the boat and here you all are discussing the very questions I got stuck on. My interest was particularly rekindled by an occasion when I was returning in the rubber duck and couldn't get the outboard started. As the landing was half a mile downwind, I left the leg in the water so that the dink lay beam on to the wind and sinmply rowed forward and back as required to maintain track.

Looking around the cockpit, I can't imagine rigging a rowlock for sculling would be too easy, but could use the main winches as a thole pin. Then I wondered whether the spinnaker winches on the quarter couldn't be used the same way with a single sweep like a gondalier uses, with body weight used to provide the assymetry needed for the boat to go straight - anyone tried that?

Rob.
 
My Hunter 490 has no engine or bracket - just a couple of 8' oars (which are the longest I can fit in the cabin for storage). It's not as bit, of course, as some of the things being talked about, but I can move its 1000lbs + crew at a respectable speed under oar. It takes a while to get going, but once its moving progress is quite satisfactory. The furthest I have rowed it was about a mile, and I wasn't at all tired. Ming-Ming (modified Corribee) only has sweeps as auxiliary power, and I think Ming-Ming II (modified Achilles 24) is the same.
 
JumbleDuck said:
My Hunter 490 has no engine or bracket - just a couple of 8' oars (which are the longest I can fit in the cabin for storage). It's not as bit, of course, as some of the things being talked about, but I can move its 1000lbs + crew at a respectable speed under oar. It takes a while to get going, but once its moving progress is quite satisfactory. The furthest I have rowed it was about a mile, and I wasn't at all tired. Ming-Ming (modified Corribee) only has sweeps as auxiliary power, and I think Ming-Ming II (modified Achilles 24) is the same.
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Can you row into the tide ?
 
Larry Pardey writes of sculling his first circumnavigation boat (around 28 foot IIRC) at an average of 2 knots on many occasions - as he had no engine it was the only alternative to sail...
 
Yes rowing is a very viable option for a small sail boat. I use 2 long oars hooked into the stern rail to grt quite decent usable speed 2knots in my 21fter. What really stops it dead is ahead wind. Of course any tide running will have a big effect if you only have 2 knots water speed. Well worth setting up your best arrangement for rowing that suits you. good luck olewill
 
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