Say you have identical triplets, all with the same weight, all with the same paddling ability. They have two kayaks, a 16 foot solo and a 16 foot tandem. Both boats weight the same, have same hull shape, only difference is one has 1 cockpit, one has 2 cockpits. Which is faster, the solo or the tandem?
It seems to me that the doubled weight would trump the doubled paddling effort, but I am willing to be convinced otherwise.
Alright, if the tandem boat is slower, let’s say we start adding to its length, a foot at a time (with the inherent weight addition) is there a point at which the increased length will tip the scales in favor of the kayak?
interesting question
While people are working on that one, I was also curious what would happen if one of the boats started 10 miles upstream, with a 3 mph current, while the other started 5 miles downstream, 25 minutes later, and towing a stardard sized Coleman cooler of beer against the same 3 mph current? Assuming the water level begins to drop at a constant rate of 0.5 feet/hour, and that there is more suckwater in the upstream section, at what point will the two boats pass each other?
Get back to me on that when you have a minute.
af
I Dont Know
But I think that the answer to your question is going to turn out to be more complex than just adding or subtracting length. Hull shape and wetted surface will be important criteria in the final analysis. As weight, (the second person), is added to the boat the boat will sink further into the water. The shape of the hull that is in the water will change and the entire characteristics of effort vs speed will change.
Mark
Depends
on how much beer is in the cooler being towed and how much time it takes to “reel in” the cooler while paddling.
happy paddling,
Mark
The tandem will leave the solo…
in it’s wake if all the paddlers are equal going by your specifications.
Cheers,
JackL
Would the beer be in a camelback…
or would they need to get out the bottle opener each time?
IDENTICAL TRIPLETS IMPLIES HAVING
THREE paddlers, so are you putting 2 of the 3 in the front seat of the tandem or the backseat of the tandem. Might affect the trim. Or did you mean identical TWINS??? LOL
READ IT AGAIN
– Last Updated: Oct-06-05 3:28 PM EST –
There are two boats, same length, same hull shape. Just one happens to have two cockpits, ie, is a tandem, and one has one cockpit, ie a solo.
Two of the triplets are in the tandem.
One of the triplets are in the solo.
The two boats are racing. Who wins?
I took the question to mean.
three triplet kids.
One in the solo, and the other two in the tandem.
If that is the case then the tandem will leave the solo in it’s wake as I stated above.
Cheers,
JackL
more issues
i think we also need to take into account the life issues these 3 people may have faced growing up as apparent copies of one another. there could be a lot of psychological issues impacting their paddling performance in a single vs the double. conceivable the two in the double might be entirely sick of working together, and might sandbag. this is really a very complex problem. i think we need federal money for this one.
af
I paddle a tandem and a solo
I would say the extra paddler in the tandem more than makes up in speed for the extra weight. All things equal, the tandem is faster (once it reaches cruising speed which takes longer).
My question answered
A definitive answer is a rare thing on this board. So the dual power of the paddlers more than makes up for the extra weight, and a tandem is faster. Cool. Thanks everyone.
(now if I could only get my 7 year old to start pulling his weight, MY tandem would actually be faster).
is…
this a case of cloning- or was it nature’s way???
maybe fertility drugs…
Weight does not matter much…
The weight being pulled PER paddler is slightly less for the paddlers in the double.
The weight is not as important as water resistance.
The double has more water resistance but probably not twice the hull resistance of a single.
Therefore, the double will be faster.
If you assume the same water resistance, then, clearly, the double will be faster than the single.
That’s the most
cogent breakdown of why a tandem would be faster than a solo.
Until your 7 year old
starts pulling his weight, the tandem will be very slow. It’s hard to paddle from the stern of the boat if you have to paddle the extra weight of a non-paddler in the bow; and vice versa.
Plus you leecock like a monster
when the wind picks up. But it’s all in good fun.
Extra paddler power doesn’t matter much
– Last Updated: Oct-07-05 10:56 AM EST –
I've done a high speed beer run with another strong paddler in a 24' glass Mirage Double. We weren't significantly faster than if we'd each taken our own boats. We were probably cruising at near 6 mph. I'd bet the guy with the QCC700 would have beaten us.
Using pump theory, a paddler is like a centrifugal pump and speed is like flow velocity through the system. Flow velocity is proportional to pump discharge pressure and it may be easier to think of pressure. There is a point at which discharge pressure/flow velocity or kayak speed stops increasing no matter how much power is behind the pump/paddler. To add another paddler is like adding another pump in parallel since both paddlers are pulling water from the same source as they stroke together.
The second paddler puts a lot more work into the water but the flow resistance or boat's drag increases exponentially with a small speed increase. When you add a pump in parallel to another in the same system, pressure and flow velocity in the system will barely increase if you are near pump capacity because the friction in the system hasn't changed. In this question you increase the boat's drag with the weight of the second paddler.
This thermodynamics makes my head hurt! But like somebody else said, you could expect maybe an extra .5 mph for the tandem on the high side.
Fun with math
Being curious about how much the wetted surface increases with load, I just cranked out a very crude approximation. It’s too early to calculate complex shapes…
Start with a rectangular flat-bottomed boat 16’ log and 24’ wide" Figuring the density of water at 62 lbs/cubic foot, draft will increase with load at 165 lbs/inch. So if the boat weighs 50 lbs, one 150-lb. paddler will draw 1.2", and two will draw 2.1". but since the bottom represents such a high percentage of the total surface area, it’s only an 8% increase in wetted surface.
If you use a 16’ x 12" box to better simulate the area of the bottom of a hull, it’s only a 13% increase in wetted area.
In both cases the submerged cross-sectional area increases by 75%.
I know that real hull shapes and hydrodynamics are vastly more complex, but if both cases are within the hull’s designed capacity, I can’t see that adding a second paddler would double the drag.
Since fluid dynamic drag generally goes as the square of velocity, doubling your power will certainly not double your top speed.
Two Things To Factor In
And these are only a few of the ingrediants. First your percentage wetted surface figure will likely increase due to the shape of a boat hull. The rocker and Vee shape lend themselves to a more than proportional increase when going deeper. And the water starts to play tricks on speed and effort as the boat nears it’s design hull speed. I dont remember exactly what takes place but something about the bow wave changing direction based on the speed. And when at hull speed the boat does not want to go any faster. At that point a significantly larger force has to be applied in order to get the boat to go even a small amount faster. (time for the third triplet)
Mark