The Lightweight Secret

Most paddlers would sit up and listen when told they could actually travel the same distance without working any harder in less time. They’d lean in much closer when told that there was a secret that could allow them to travel an additional 24 miles in a ten day trip without any additional hours on the water, and most would be surprised to learn the secret is actually simple. Simply, traveling with less and lighter equipment allows a paddler to go significantly further or faster with no additional time or work. Or perhaps more intriguing, this also means that traveling the same distance requires less work.

Resistance Explained

The force behind this secret is called resistance. As a canoe or kayak moves through the water, the water opposes the craft’s movement. And this opposition is represented as resistance, which breaks down into two types: frictional and residual. Frictional resistance is the energy lost due to friction between a layer of water that attaches to the hull and the layer of water that the hull passes through. Residual resistance is made up of all other resistances and these include pressure drag, eddy-making drag, and wave-making drag. The main force of residual resistance is wave-making drag. When moving through water, the kayak or canoe creates waves and the energy used in making these waves is a loss in energy used to propel the craft and a gain in resistance.

Boat designers are concerned with resistance because they can use it as a tool to create a more efficient boat. In larger ship designs this could equal a huge amount of savings in fuel expended and thus result in a lower cost of operating the boat, but even in small craft like kayaks and canoes, resistance plays an important role. Less resistance means less work for the paddler to go the same distance or the same speed. Even small decreases in resistance equate large gains in efficiency. For example, a 2% gain in efficiency at 4 knots means that the paddler will gain two minutes on an hour. (Winters, John, The Shape of the Canoe, Second Edition, page 66) Over an eight-hour day, the paddler with the more efficient boat will arrive at camp 16 minutes before his friend who paddles a 2% less efficient boat. Over 10 days, the more efficient paddler will have gained 160 extra minutes for the same amount of work and energy expended. If this paddler stays on the water the full eight hours, then over the 10 days, she will have paddled approximately an additional 12 miles during the same time. It’s not hard to imagine, as will be shown, a 4% or even 8% gain in efficiency, which would result in 24 or 48 miles, respectively.

Measuring Resistance

For canoes and kayaks, John Winter’s KAPER drag prediction program has become the main way to measure resistance, and Sea Kayaker Magazine has adopted it as one of the results used for performance prediction. If numbers that are more accurate are needed a tank test can be preformed, but this is impractical and expensive for most paddlers. Michlet, another drag prediction program, is also available and it uses the whole hull shape to predict drag and may be slightly more accurate than other methods, but for comparison purposes, using only one of these methods will be accurate as long as it is consistent internally. Here, the original KAPER as integrated into Delftship Professional (Opens in New Window) is used. It is important to remember that moving water interacting with wind and waves and current is an environment that can be hard to predict, and because of that, the formulas in these cited programs should not be considered absolute, but they are the best we have.

Extra Pounds Equal Extra Work

Sea Kayaker Magazine states that the average kayaker can maintain three pounds of drag over a long period of time, and this seems to be slightly conservative, so for this test four knots of speed was selected as a speed to predict resistance. This speed was selected because for most kayaks at most weights, three pounds of resistance occurs near four knots. For these results, three kayaks were selected: the Siskiwit Bay, Intrepidation, and Igdlorssuit. These three boats represent kayaks ranging from 16.5 to 18 feet, and also represent a broad spectrum of kayak types, from a modern touring kayak, to a coastal playboat and finally a traditional Greenland boat, respectively. Even though these boats represent a wide range of crafts, they all could be used as touring kayaks, and an increase in efficiency would result in major gains in speed and or distance over a typical day spent touring. Almost any canoe or kayak and speed could be used and the results would be similar. As is shown in the following chart, Displacement vs. Resistance, resistance at four knots is plotted against displacement. Resistance was calculated using KAPER at every 25 pounds of displacement from 150 pounds to 350 pounds.

As the chart clearly shows, resistance increases as more weight is added to the kayak. When the three boats are averaged and the resistance increase between each 25-pound step is averaged it is shown that for each 25 pounds extra carried in the kayak, resistance increases 4.56%, or .0114% per ounce. The reverse of which is that if you carry 25 pounds less, a paddler will gain at four knots over four minutes on an hour or she’ll arrive at camp about a half an hour earlier traveling the same distance over an eight hour day. (It should be noted that the increase in resistance is greater at the ends of this displacement range than it is in the middle. The following chart, Average Increase in Resistance as Displacement Increases Per 25 Pounds, shows the percent increase at each 25-pound step.) So, what is happening? Adding weight to a boat increases the wetted surface, and for the most part, it is this extra wetted surface, which increases frictional resistance, that is causing the extra drag.

Real Life Examples

As the first chart dramatically shows, gaining efficiency is as easy as losing weight. Losing 25 pounds is much easier than it sounds, but it does require some slight change in the gear carried. For this example, the paddler is paddling a 45 pound boat, carrying 35 pounds of camping gear (average for traditional camping methods), with rescue gear, vest, and paddles, he weight 205 pounds. He is also carrying ten days of food at two pounds a day or 20 pounds in food. So, his weight is 305 pounds. On the chart above, he is generating about 3.56 pounds of resistance at this weight. Now, if he were only to drop his camping gear weight to that equal with this list, he would drop 21 pounds out of his kayak and he would be generating around 3.45 pounds of drag. This simple change in camping technique gains the paddler about a 4.4% increase in efficiency. That’s 24 extra miles paddled in ten days paddling the same eight hours a day. On a 360-mile trip, that finishes the trip almost a day earlier than planned.

Taking the example further, the paddler could lose five pounds by buying two carbon fiber paddles, build or buy a kayak that is lighter at 38 pounds (Lightweight Cedar Strip Building) he could adopt Ultralight camping methods and drop his camping gear to eight pounds. This would lose him 39 pounds and gain 7.11% in efficiency, and it’s not hard to imagine that the paddler, himself could lose 20 pounds, use infused carbon fiber to drop the weight of his kayak to 30 pounds (many Kevlar solo canoes weigh this now,) go radical with his camping gear to a five pound level, and drop 70 pounds of weight. In this final example, the paddler gains an increase of 12.7%. This would allow the paddler to finish the above trip two days quicker, which would allow him to drop two days of food for four pounds and would thus increase the efficiency to 13.6%. Over one day, going the same mileage as before, by losing this weight, the kayaker using the same energy will arrive at camp 1 hour and 40 minutes earlier. That’s a lot of extra camp time for exploring, taking pictures, relaxing, etc…

The above efficiency gains, shown in increased miles, decreased paddling time, etc… can be mixed up any way a paddler chooses. For example, if the paddler gains four minutes a mile, that’s 24 minutes to play in waves, fish, relax under the sun, explore, do anything imaginable and still arrive at camp without any extra work other than that expended during the chosen activity. It doesn’t get any better than that.

Of course, saying that in all sea conditions, with all boats, and all circumstances, these gains will be realized would be over simplification of the issue.

Other Advantages

In addition to the advantages mentioned above, an increase of efficiency results in several other advantages. Some of which include: having a more nimble kayak or canoe which accelerates faster, is easier to turn and move quickly in dangerous situations, and it could be argued that because the paddler is able to cover more ground quicker, she’ll be exposed to dangers for a shorter duration of time and thus will be safer. Also, lighter weights equal easier carries on and off the beach and easier portages.

The Trade-offs

There are some trade-offs and the main one is that more skills are required to use lighter weight gear, but these skills are basic and should be mastered by all outdoor travelers anyway. Also, in some situations, there may be an advantage to carrying extra weight, like when extra stability is needed. Like in storm ravaged seas. This can be addressed on the water by filling extra water containers to increase stability. This solution allows the paddler to take advantage of the gain in efficiency in the normal conditions that occur most of the time, and still be able to gain the extra stability when needed.

Edit: With a properly fitted kayak, I believe that lighter weight isn’t a trade-off in this situation.

Also remember: In order to maximize the advantages of efficiency gains, it’s important to paddle a canoe or kayak properly sized and designed for you and your gear and the conditions you expect to be traveling in, respectively.

Anecdotes Against

There are some anecdotes that can be made where the advantages gained by decreasing weight in your load would seem to be overcome by disadvantages of doing so. For example, in this outragous and often cited example, if a 125 pound person is paddling a kayak designed 300 pounds, some added weight may help the person keep the kayak tracking better, add extra stability, and that in and of itself may get the kayaker to camp sooner. But just because one can come up with anecdotal imaginings where extra weight may be helpful, it doesn’t discount the facts stated in this article. It’s like saying that because one smoker lived to be 100, that smoking isn’t a health problem.

Tracking and Less Weight

Most paddlers switching from traditional camping methods to lightweight methods usually save around 25 pound, which in the boats listed above changes the waterline by about 5/16″ of an inch. One could imagine that this decrease in waterline in the extreme examples (i.e. 70 pounds of dropped weight) above may decrease tracking enough to reduce the benefits of efficiency gains somewhat. This may be the case (As far as this author knows, no study exists for this), but it is doubtful that they would reduce them significantly particularly in the real life weight reductions that occur when switching from traditional equipment to light-weight equipment.

The Momentum Argument

I understand the momentum argument, but there’s a point at which the momentum that carries speed between paddle strokes and the increased resistance meet. At this point, the increase in weight drowns out the gain from more momentum. Based on rough preliminary calculations for a lean and efficient paddler with no extra fat, the dead weight (including boat, gear, paddles, etc.) should weigh around 20% of the person’s body weight–anything more just slows the paddler down.

Advantages, Advantages, Advantages

Given the study, it is clear that a reduction in weight carried while paddling results in positive results. With the shown on average 4.56% gains in efficiency per dropped 25 pounds or .0114% per ounce, it’s clear that traveling lighter not only has advantages off the water when the gear is on your back, but also on the water when the gear is stowed in the boat. And that’s the secret. Now get out and paddle. Give it a try to see what you think.

Additional Resources

• Effects of Weight in Rowing