rowing vs. kayak

whats the difference in speed between say a shearwater 17 and an  annapolis wherry tandem [one rower]


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RE: rowing vs. kayak

I can't vouch for comparative speed. The naval engineers on this forum can probably tell you theoretical boat speed based on the dimensions of each craft. Of course, it'll depend on the rower/paddler ;).  With regard to strength and fitness, I favor rowing as a full body workout. As you build strength and endurance, you can make either of those boats move fast enough. I've calculated my rowing speed (solo Annapolis Wherry Tandem) at about 6 knots sustained for about an hour. Olypic rowers in race craft can reach speeds of 14-15 knots in racing shells. Cleary the Wherry is not a racing boat. 

 

JF

RE: rowing vs. kayak

I am not sure anybody can answer your question without better understanding of what distances you will be going, what kind of a load you will be carrying and what conditions you will be facing.

I am a fit 52 year old and my GPS says that I average 4.7 mph on 10-15 mile paddles in my 17LT in benign conditions.  Of course, speed drops in constricted waters and adverse conditions.  I would expect a Shearwater 17 to be slightly faster.

I suspect that the wherry would be faster over short distances but the kayak would be faster over a long haul.  Certainly a wherry could never keep up with me on some of the waters that I kayak because they are so narrow that both oars could not be used simultaneously.

    

RE: rowing vs. kayak

I believe the answer is contained more in the boat design than the method of propulsion.  Generally speaking, speed is a function of boat lenght. For any given lenght of boat, (except when surfing) the energy required to exceed hull speed increases dramatically.  Thus for an 8ft boat the amount of energy required to go from say 2mph to 3 mph may be minor, but from 3 to 4 can be more than twice and from 4 to 5 may be 8x as much.

 

The real difference between the two boats is what you can carry at that speed. Kayaks are not designed for high load, so paddling works.  Boats that carry higher loads are all row boats. I think this is to bring into play larger muscle groups.  That said, the human can only deliver so much power no matter what. I believe I've heard about 5hp is the maximum a human can deliver.

 

I have an eastport pram and have done some experiments with a Torqeedo.The pram weighs about 80 pounds and is 7 feet, 7 inches long. I found that adding a second person didn’t really affect the power consumed. For the pram, the watts/speed values are: 9.5 watts/1 knot, 19 watts/1.5 knots, 39 watts/2 knots, 52.5 watts/2.5 knots, 107.5 watts/3 knots, 67.5 watts/3.5 knots, 425 watts/4 knots, 850 watts/4.5 knots, 1,005 watts/4.7 knots.  If you graph these numbers out, you can see why adding horsepower just wont matter. 

Thus, speed is more about the boat design and paddling vs rowing is more about what is needed to get that load moving and how long on can move that load.  If you tryied to kayak a 300lb load, I suspect it would be difficult.

 

George

RE: rowing vs. kayak

wow !! so.... which is faster?

RE: rowing vs. kayak

A Shearwater 17 will be faster than the Annapolis Wherry Tandem rowed solo.  This would be true both in a sprint and over some distance, I think.  The single Tandem Wherry rower will be drier, and can carry bulkier gear, but will be fighting much higher wetted surface.  

With two people in the Annapolis Wherry Tandem, the race becomes more interesting.  My guess is that the Shearwater 17 and AWT would be a pretty good match in a sprint, based on the strength and skill of the paddler and oarsmen.  Over any distance the AWT would begin to pull away and eventually leave the kayak well behind because of the horsepower advantage.  

A single Annapolis Wherry vs. a Shearwater 17 would be an interesting race.  I think it'd be close in a sprint, but would go to the Wherry over a few miles or more.

 

RE: rowing vs. kayak

Hey John, et al,

What would you expect to see from a NE Dory, with two people in the boat (my Wife and I) comparing just me rowing vs her also rowing?  What incremental speed would you expect to see?

Thanks

 

Curt

RE: rowing vs. kayak

A lot depends on your mutual timing. Your rhythms have to be in synch. Then there's your weight vs. her weight and where you both are sitting. Plus your relative skill levels. If you're very much better than her, then she's just ballast. If she's very much better than you, then you're the ballast.

So it's unanswerable for the specific situation you described without more info.

Once you finish your boat, try it out and tell us.

Have fun,

Laszlo

 

 

RE: rowing vs. kayak - sounds like some okoume-fest experiments

john,

sounds like you should incorporate some of these experiments into fesitivities at okoume fest.

wherry v kayak

kayak v kayak

won't be scientifically rigorous....but it may be fun/interesting

on the question of the incremental speed difference with another rower (wife), holding all thinks constant, the incremental speed is going to be where on the power to hull speed curve you are. 

if you think about power on the y axis and the speed on the x axis, as you add in power the boat speed increases with diminishing marginal return as you approach hull speed.....where basically you can't go any faster (unless you can pop the boat up on a plane....which is probably not going to happen on a dory.)   so if you alone have enough power to approach hull speed, your wifes contribution is going to make little difference in speed.   

my intuition, after spending a lot of time in a double with my daughter in a circumnavigation of crete, is that it will be less about speed, but about your ability to maintain speed with a greatly reduced effort...which has a big impact on endurance (the ability to maintain a given output over time)   

our double almost always arrived first in our party (which also included a number of singles) in our trip which included seven back-to-back days of 20 to 35 miles of paddling.   but it was not really about outsprinting the other boats, they just were fatigueing before we were.  which in the end...i guess amounted to a to us getting there faster if the distance was long enough for endurance to be a significant factor.

RE: rowing vs. kayak

just a couple more comments on boat speed and the effect of another paddler to go with my previous comments.

look at johngalts comments above to do a graph of power to boatspeed or the hull speed curve.   here are some important other factors and a way to play with the curve.

all hulls have design displacement weights....where the boat pretty much sits on the lines the designer expects.  the theoretical boat speed/hull speed of the boat, in most designs, stays pretty much fixed if you are within the design displacement range.  if you are within the design displacement range, the boat's not getting a substantially different waterline length and wetted surface area is staying pretty much constant.  so adding weight within that range doesn't change the boat speed significantly.

most displacement hulls, including a modern kayak design, are designed to be capable of approaching their hull speed with the 'expected' motor.   that is why a human-propelled craft like an 18 foot kayak does not look like an 18 foot motor boat.   speed is a desired characteristic.   most people would be very unhappy with the result of paddling an 18 foot motor-boat hull.  

most twin paddle craft that occassionally are expected to be handled by a single person  are not designed to require two units of power (two people) to achieve their cruising speed.   its somewhere between one and two units.  so if we assume the double needs 1.5 units of power to achieve its cruising speed (which is often defined as 80% of hull speed ~ 4knots/425 watts on johngalts craft) two equal people working together (assuming equal capabilities) only have to put out 315 watts apiece (425 watts X 1.5 divided by 2).  vs the person in a single has to put out 425 watts.

so the folks in the double only need 75% of the effort to maintain the same speed as the single (assuming the double and the single have pretty much the same hull speed) ....and that can typically be sustained over a longer time. 

to the extent they want to use their extra power to match the power output of the single, they will go faster than the single but as johngalts graph will show, as they approach hull speed their power advantage won't translate to much of a speed advantage.

in the example above, if the double only has a single person on it, he would have to maintain an output of 630 watts to keep the same reference cruising speed compared to the (150% of what the single is putting out)

most people only have a certain amount of power they will put out over an extended period of time (non sprint)....so the crusing speed is going to settle in to match the output of the paddlers over the length of the journey.  my sense is that when not racing, paddlers of double designs i see hit their cruising speed and conserve energy and use their power advantage to have increased endurance which then becomes a 'speed advantage' over a long distance. 

now that you have the factors and bit of a framework, you can play around with different assumptions about the the two paddlers, the ratio of power to get a double moving at the same speed as a single, etc.

RE: rowing vs. kayak

final comment....

in the case where a single person is rowing a double and only puts out the same output as the single, he is going to slide back to the left side of the power curve and his speed will drop substantially becuase a unit of power in that direction is having a larger impact on hull speed than to the right side of the power curve.

that is why johnCLC, i suspect, is saying that a single kayak will beat a double rowboat if only one person is rowing.

RE: rowing vs. kayak

intresting, bring a tandem wherry to merrit island and i'll bring my shearwater and we'll experiment. ps i'd really like to see more of your newer line of boats at the demos [i guess its because most of them are on the larger side and harder to drg around the country]

RE: rowing vs. kayak

which one [rowing or kayaking] do you feel more comforatable doing over long distances?

RE: rowing vs. kayak

Personally, if I want to go FAST on the water I'll use the bay boat.

RE: rowing vs. kayak

People have crossed the Atlantic in both rowboats and kayaks, so I think it comes down to whichever style you are more comfortable with. Over any kind of distance I would want to have a sliding seat for rowing, but again it isn't a requirement--the first rowing Atlantic crossing was done in 1896 in an open dory with fixed seats.

Kayaks do have the advantage of being closed boats, and so generally better able to handle rough conditions. Sliding seat rowboats let you take advantage of the larger leg muscles, so you can put out more power for longer, and with less fatigue.

Obviously the fastest human powered boat would be a racing shell, but there's no way I would want to take one of those any distance.

It ultimately comes down to knowing what you plan to do with the boat, and choosing one that fits the task:

Something like the wherry or dory was designed to haul cargo and people, and so they can move a lot of mass at a low to moderate speed without too much effort.

Kayaks were originally designed for hunting seals, and so can move a comparatively small load quickly, and with a fair bit of agility.

Racing shells go really fast in straight lines and can't handle much more than the weight of the rower(s).

Which one do you prefer? Rowing or paddling? That's the one that will be the most comfortable over long distances assuming you don't try to push your boat beyond the limits of its design.

RE: rowing vs. kayak

   I just finished my ne dory and can now answer my own question .I need to get the GPS out for exact info but my first impressions are in low wind conditions I can keep up with kayaks. If the wind picks up though I'll be struggling, there's a lot more boat sticking out of the water. As it's intended to be primarily a sail boat that shouldn't be a problem 

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