A Game Of Inches And Ounces

If you wanted to win or even be competitive in the Boston Marathon, would you wear a 25lb (11kg) backpack and 3lb (1.5kg) hiking boots? My guess is that you probably wouldn't, you'd probably opt for light shorts, light comfortable runners that provide contorsional support and maybe a ball cap to keep the sun off your head. As a runner, you'd try to be as light and efficient as possible. Ultramarathon canoe racers and runners actually have that in common.

Outside of technique and physical endurance, canoe racing over extremely long distances is a game of inches and ounces, a race where when you look at the physics, you can reap major benefits from minor sacrifices.

A MATTER OF INCHES

All other dimensions equal and paddling being equal, which canoe do you think will be faster, a canoe with a 17' waterline or a canoe with a 16' waterline?

The fact is, what many people (recreational canoeists included) don't realise, is that if you have a canoe with a longer waterline, you will actually have a faster theoretical maximum speed compared to a canoe with a shorter waterline. Let's look at a boat with a 17' waterline (Canoe A) and a canoe with a 16' waterline (Canoe B).

Without actually deriving the formula, the equation to determine the theoretical maximum speed of a canoe/kayak in miles per hour (mph) is 1.55 x SQRT(wl) where wl is the waterline length in feet.

Boat A: 1.55 x SQRT(17) = 6.4 mph (10.29kph)

Boat B: 1.55 x SQRT(16) = 6.2mph (9.97kph)

This may not sound like a lot, a mere 0.2mph (0.32kph), but over 1 hour, that amounts to a distance of 350 yd (320m) or almost a 2 minute lead. In typical marathon races that take 5 to 6 hours to complete, that distance can increase to 1mi (1.6km) and be a time of 10 -15 minutes. In an ultramarathon race such as the Texas Water Safari, over a time of 80 hours, the difference in distance can be 16 miles (25.6km) and a difference between boats of almost 2.5 hours. This scenario is of course under optimum conditions with a zero-sum flow and not accounting for fatigue.

However, races are never under optimum conditions and fatigue is something that everybody has to deal with as well as the fact that with each stroke, the canoe is pulled/pushed forward, but unfortunately the power from each stroke is applied off-centre at an angle to the centreline as such, the canoe will not track perfectly straight as energy is lost and distance is gained as the canoe angles off centre. So what can you do to minimize lost energy?

A MATTER OF OUNCES

Without changing to a canoe with a minimal rocker or keeping synchronized and equal power strokes, you can mitigate energy loss and thus increase endurance by shedding weight, and the weight doesn't have to be much.

If you opted for a carbon fibre paddle that weighed a mere 6 ounces over a wooden paddle weighing 18 ounces, you would find yourself lifting 12 ounces less per stroke. But these 12 ounces equate to 2,025lbs (919kg) less per hour. Over a typical 5 hour race you would be lifting 10,125lb (4,595kg) less. In the Texas Water Safari, a boat finishing in 80 hours would lift an astonishing 810,000 lbs (367,600kg) less.

One of the better ways though, is to actually have the racer lose weight. If a paddler gearing up for a race can lose a mere 5lbs, over the course of 1 hour and holding 45 strokes per minutes, the paddler will be pulling 13,500lb (6,124kg) per hour. Over a 5 hour race that's 67,500lbs (30,620kg) and a boat finishing the Texas Water Safari in 80 hours would be pulling 1,080,000lbs (489,900kg) less through the water. That's over 1 million pounds.

This weight savings also comes into play when portaging, lifting the boat over log jams and of course minimizing friction. As more weight is placed into a boat, it sits lower in the water causing greater displacement of water and greater friction, meaning more force (and energy) is needed to move the boat. If you want, you can calculate the force needed to move a boat of different weights by using the following equation. Rf = 0.97 x Cf x Sw x V^2 where Rf is Resistance in lbs, Cf is the friction co-efficient, Sw is the wetted surface, V is the velocity is feet per second and 0.97 is the fresh water constant.

This weight reduction can be added to almost any aspect of gear you can think of taking, from sleeping pads, to pfd`s, to food. And don`t worry, we`re keeping all this in mind as we prepare for Texas.