Jim Crescenzi, a reader in Cambria, CA was curious about the differences in speed for kayaks reported on in our kayak reviews in Sea Kayaker
magazine. Jim made a graph of the speed/resistance numbers of 18 kayaks and posed an interesting question:
The kayak reviews by Sea Kayaker
magazine are a real service to your readers. A couple of years ago I studied the reviews carefully before selecting my personal kayak. One of the considerations was kayak speed. The calculated Broze/Taylor metrics seemed to be especially valuable as they provide a means of comparing different kayak designs.
My impression is that most paddlers have difficulty exceeding a speed of 4 knots (4.6 miles per hour) for any length of time. It was of particular interest to plot the speed versus resistance (Broze/Taylor) included in your reviews of eighteen high performance kayaks, with lengths varying between 16 and 20 feet. The heavy black line is the average for all eighteen kayaks.
It appears that all eighteen kayaks are very similar in force required for speeds below four knots. The designs distinguish themselves at speeds of 4.5 knots or higher. Generally, as one gets to 5 knots (5.75 miles per hour), the faster boats were at least 18 feet long. However, that extra length appears to be of little advantage at speeds below 4 knots.
Is this interpretation correct? If so, most of us would be far better off focusing on our conditioning and paddling technique than on boat design!
I notice that the reviewers’ comments about speed don’t always correspond to the Broze/Taylor metrics, so perhaps there is an additional subjective consideration. Your comments would be appreciated.
Jim’s observations are right on target and his graph is quite similar to the one we published in a review of five kayaks in our Fall ’86 issue. In the beginning of our kayak testing program, a number of kayaks were put through resistance trials in a towing tank operated by Canada’s B.C. Research Ocean Engineering Center. The five kayaks reviewed in our Fall ’86 issue varied in waterline length from 15’ 1” to 16’ 1” and in prismatic coefficient from 0.45 to 0.52. The range of resistances recorded at towing speeds of 3 knots was less than the towing tank’s degree of accuracy—3/100ths of a pound. At speeds up to 4 knots skin friction (a function of the hull’s wetted surface) is the main component of drag. At speeds above 4 knots the wave-making resistance (a function of waterline length and prismatic coefficient), the other component of drag, becomes more significant and the kayaks begin to show more readily detectible differences. In the simplest terms, kayaks with a longer waterline have the potential for higher top-end speed than kayaks with shorter waterlines. As Jim points out, few cruising paddlers can sustain for long periods of time those speeds where wave-making resistance comes into play. (It should be noted that the standard applied to our testing program is for a weight of 250 pounds aboard the kayak.)
There are some subjective factors that account for differences between the reviewers’ accounts of boat speed and the resistance figures. Light kayaks, especially when they aren’t loaded with cargo, are easier to accelerate than heavy kayaks and the quickness can be part of a subjective interpretation of speed. An extra 10 or fifteen pounds in a kayak’s weight adds very little to its surface area and waterline length, and consequently to its drag.
Kayaks in a towing tank move in a straight line. Kayaks propelled by a paddler yaw in response to the thrust of the paddle on alternating sides. Excessive yaw will slow a boat down, so a kayak that resists yaw effectively is better at converting paddling thrust into forward speed.
Conditioning and paddling technique do play a very significant role in how fast a kayaker can paddle. The paddle is also an important factor: a heavy paddle can drain power and diminish speed. It is also wise to consider the effects of paddling in a group. If a group of kayakers sticks together (and as a rule, they should), the group can only travel as fast as the slowest paddler. One way to speed up the slowest paddler—and keep the fastest from racing ahead—is to shift some of the heavier cargo from the tortoises to the hares.
The numbers that we provide in the kayak reviews can be put to very good use when comparing sea kayaks. They provide objective measurements that can help you distinguish how various kayaks will perform. The human factor is perhaps the greatest factor. You’re the engine and the drive train. The numbers can help you find the kayaks that are best suited to your kind of kayaking.
For more information on our kayak testing procedures please refer to our web site: