# Physics of kayaking

Alright, here’s the deal. To give a short introduction, my name is Alex and I am a highschool student in Eastern Canada. I am in my senior year, and as a last project for Physics 120 we are to take something from the real world and apply the use of physics to it. I, paddling for four years now decided to do it on kayaking.

At home, we currently own two Necky Zoar Sport kayaks and I thought that I could do something regarding them, and the experiment has been approved. I just need to figure out how I am going to pull it off properly, because quite frankly I need these marks.

The experiment that I was thinking of doing was using a personal GPS system to measure out a distance on the cove just meters from my house, and use the GPS again to find my velocity over the distance. Then perhaps, put weight into the storage compartment and try it again to find an acceleration vs. mass thing. The experiment doesn’t exactly have to be all that groundbreaking, as you can tell.

I know that Newton’s second and third laws come into play while paddling a kayak, due to pushing against the water and the water then propelling you forwards, and I know that torque is there in the way that the paddle works as a lever arm. I was just wondering, if there is something more than I can find (if you search Kayaking physics, one site comes up and that’s where I found force orque but there really isn’t that many kayaking resoruces on the net) out about the whole deal.

Topics

– Last Updated: Apr-12-06 12:57 PM EST –

You could use a heart-rate monitor as a rough measure of power output, and compare that to speed or acceleration.

You could calculate the torque produced on the boat by different paddle lengths or distances from the centerline to show why it's harder to paddle straight with a long paddle, or a low-angle stroke.

You could look at the height of the center of mass versus roll stability.

You could look at the physics of rolling, and how different techniques change the relationship between the center of mass and the center of bouyancy:
http://www.atlantickayaktours.com/pages/expertcenter/rolling/Rolling4.shtml

You could look at drag as a function of paddle blade area, blade shape, and speed through the water.

You could compare lift & drag of a high-aspect-ration symmetrical airfoil(greenland paddle) to a low-aspect-ratio cambered plate(euro paddle).

You could look at ventilation and vortex shedding on paddles, boundry layer control on hulls, angles of attack on rudders & skegs.

There's a lot of physics involved here....

Well, my friend Franz accidentally
dropped his expensive kevlar kayak off his car top. And like Newton’s apple, it moved in a direction towards the center of the Earth instead of away from it.

Franz therefor concluded that:

a) Einstein may have been on to

something with the curvature of

space-time.

b) Kevlar may have high tensile

strength, but low impact

resistance.

My suggestion
is to use the GPS and a heart rate monitor in an effort to determine if it is more efficient to use a rudder, over a specified track, at the same speed, or to do the same course without a rudder.

Belton

Power
If you can determine the craft’s efficiency at different drafts, loaded and unloaded, you could calculate paddling force required and convert it to calories. Then you could verify calories burned with a heart rate monitor. You should be able to make an approximate comparison for a pretty good grade. For extra credit you could factor in a head wind.

Taj

I’m not a physicist, just an electrician who understands power in watts, HP, joules, and mechanical force.

Mass and Drag
The more weight you put in your boat, the more hull is below the water line… greater drag.

A variable you need to watch out for if you are doing multiple tests is wind. You might consider an ‘out and back’ route to negate any wind advantage / disadvantage.

1/2mvsquared
Keep in mind there is kinetic energy in the water that when, as you said, force is applied to the paddle, the energy moves up through the paddle shaft, through the arm and torso down through the leg and foot to the footbrace of the boat to move the boat forward.

Too complicated
for a term project, this is probably too ambitious.

A kayak moves in all directions, forward/back, side to side, up/down, rolling (dump!)… To analyze all of them, it’ll take a year and will probably ended up being a Ph.D. thesis!

I’d suggest to concentrate on the forwrad movement-- the most important one.

So let’s see:

– there’s forward propelsion which you do by pushing on the water with your paddle;

– the friction of the water that slow you down when you stop paddling;

– the wind that may help or hurt your forward movement;

If the net of all these forces are bigger at the forward direction, your boat moves forward. The acceleration and speed will depends on the mass of the boat+padler+cargo. By varying the cargo weight significantly, you should have different acceleration & speed for the same paddling force (assuming the wind doesn’t change in the interim).

GPS can be used to measure speed, while heart rate monitor will make sure the paddling force are more or less the same during the test.

That’s already quite a handful of variables to deal with.

alot of feedback here
I would agree with only testing one direction. then the variables…could you get into an olympic pool? and maybe use general force. your paddling will increse and decrese. what about pulling with, say, a handheld scale to measure foces. then add weight to the hull. as it gets heavier the drag friction will increase. Then again I was not a Physics major, so the inertial force would be increased each time you add weight…

Okay I am no help, but I enjoyed sitting here picturing all this.

Liveoutside

As stated by others…

– Last Updated: Apr-14-06 11:06 PM EST –

There are many variables to contend with. Many that can not be repeated consistently.

Keep it simple. As was already said, concentrate on forward motion. The only variable you may want to contend with is the weight (load) of the kayak.

Come up with some way to propel the kayak (less paddler) in a forward motion with exactly the same force each time. Add weight each time and measure the glide.

You can rig some sort of bungie that could slingshot the kayak forward. Set your sling up in such a way that it it will have the same amount of force exerted each time.

Chart your measurements and add weights in even increments of say 10 lbs each time. Bricks might be a good option.

A thought for a sling would be something like this. Attach a long pole (6') to the rear deck of the kayak. The pole should protrude to the rear of the kayak. Put a notch in the end so it can be put into a bow (bow and arrow setup) Retract the bow to a lever that can release the flex of the bow and propel the arrow (kayak) forward. Measure glide, add weight and repeat.

More thoughts! See if you can do this in a pool. Also, if you can, measure displacement. That will change as you add more weight to the kayak. Mark the point at the water line with a piece of tape. Do this each time you add weight. Later, add measured amounts of water to the inside of the kayak in order to determine the displacement. Try and use a kayak that has no bulkheads.

Remember, that your findings would be unique to the kayak you test only. Other kayaks would behave differently and have different results.

Andy

Get some midgets…
About five or so, and start off by placing one of them in the water at your bow. Communicate to it somehow (by grunting, sign-language, corrective-beatings; whatever is the most effective way to communicate with your midget) and tell it to grab the front of your kayak and kick its little legs against the force of your forward paddle.

Do this for a predetermined distance, say 181 feet, and record the time it takes with one midget, two midgets, three midgets, etc. Make sure you take into account any variations in wind or current, if applicable.

Once you have your midget data-sets, then crunch your numbers and using your different midget-coefficients, come up with the standard midget power and define your forward speed in a kayak.

I can paddle about 181 feet per minute with 11 midgets pushing against me. Therefore, I’m an 11 midget-power paddler. Try it out and see how many you are, it’s fun and educational.

Yo Shampoo Guy
Don’t you have any comments about all of these recommendations presented to you?

Try a different approach
Try two runs

First run with no compounds applied to the hull- no 303 or wax or anything that could help possibly reduce drag. Then try one with a compoind applied such as one of the above. It is very simplistic and it may be but if you take a large enough sample 2-3 runs for each it may at least provide some interesting data on the perceived advatanges of such materials. Use gps to track speed and distance over the course. also mark the course by waypoints using an established coordinate system, in Canada UTM is a good bet. Then you can also show cross track error thus providing an analysis tool when looking at you data. Above all have fun and the very best to you in school.

Cheers.

P

Sorry it took so long…
But thank you for all the comments and suggestions. This is going to be a real help in what I am going to end up doing.

distance and speed measurements
I suggest you use GPS to measure the distance between your start and end points to set up the test course, but do not rely on GPS to measure speeds in your experiments. GPS speed measurements can be numerically “noisy” at kayak speeds and will likely introduce an additional source of significant error in your measurements.

For your start and end points, don’t use buoys, which drift around their watch circles with wind, waves and tide.

A better approach would be to have an assistant measure the elapsed time as you traverse the course, then calculate the average speed by dividing the distance by the elapsed time. That will average out short term fluctuations in the speed and result in more reliable measurements than you’d get from a GPS.

Consider also that if you begin at one end of the course from a standing start, you’ll see the effects of boat mass on the initial acceleration as you come up to speed. Depending on what you’re trying to measure, you might prefer to enter the measured course having already gotten your boat up to speed.

I use physics all the time in everyday life. It’s endlessly useful and beautiful. An appreciation of that perspective makes this world we live and paddle in a much richer place.

Best of luck!

coil
There is a lot of coil and leverage. Almost like your straight left arm in golf. Straighteneing right leg- like judo- helps move right blade thru water.

the weight issue
i would rather see the results of an experiment engaging Archimedes, showing that weight is practically inconsequential in a kayak–this concerning work expended over time…its one reason i love to paddle camp because the kayak could care less about how much weight is in it…this ‘care less’ is what you would show mathematically.

Midgets- Random Guy
Wow Random Guy - way to go with that fun and educational suggestion sarcastic.

You sound really well educated to me. Next time you should see which other minority group you can further help to stigmatize.

Oh and as a suggestion - communicating with ‘People of Short Stature’(Yes, ‘midget’ is very offensive)is usually done verbally.

If you can’t be ‘funny’ without paying out disabled people - then don’t bother.

more
you could also calculate the buoyant force acting on the boat (equal to the total weight of the boat + paddler as long as you are floating), and determine the water displacement (different in salt water vs. freshwater) using archimedes’ principle.

It’s passed in…
Well the outline is at least. I decided what I am going to do, and it’s all laid out now. All I have to do is… actually go out and do it I suppose. I hope for some nice days on the way.