CANOE DESIGN

TABLE 1

    The results from a study like this never yield absolute answers. They can identify trends, however, and allow for informed comparisons between similar canoes (don't try to predict kayak performance with this data). My conclusions are:

STABILITY: Designs 1&2 are very stable, with #2 having a slight edge (I have no idea why). #3 has 20% less stability, and would require some attention and a higher skill level. #4 is close to unstable, and would be a real handful to control. Stability reduces with increased rocker, as the underbody begins to take the shape of a "ball". Trim is effected in much the same way. The first three are all similar with respect to trim moments and weights, and should not be too sensitive to load changes. #4 is far more sensitive, since its flotation is concentrated in the center of the canoe. It appears that some rocker can be tolerated, but anything extreme would have poor stability and load carrying characteristics.

MANEUVERABILITY: Raising the ends of a flat, no rocker design (#2) reduces the moment of inertia (turn resistance) by 9%. Adding a slight rocker (#3) reduced it by 23%, which should not be a problem for an experienced paddler. As expected, #4 has the lowest turn resistance, and would be difficult to keep in a straight line. As a second thought, I added a 4"x8" skeg to the back of #4, and it brought the moment of inertia back up to 63. No real surprises here, except that a slight amount of rocker seems to help turn performance a lot more than raised ends. Moving water with the ends of the canoe takes a lot of effort!

PERFORMANCE: As the amount of rocker increases, the cross sectional area increases, but wave drag is reduced. This sounds backwards. Pushing a larger area through the water should result in more drag (paddles work that way, right?). Wrong. Wave drag on a canoe hull is more sensitive to how "sharp" the waterlines are than it is to cross sectional area. Even though the midships cross sectional area of #4 is 42% more than #1, its predicted drag is 16 % LESS. Canoes #1&2 push the water apart quickly, and pay a drag penalty. Rocker takes volume out of the ends of the boat, which tends to sharpen the waterlines. Sharp, fine ends are common in racing designs, but it's interesting that even a slight amount, like #3, results in 11% less drag than #1, and 9% less than #2. This amount of reduced drag would be very noticeable after a few hours of hard paddling.

    Like I mentioned earlier, canoe design is more art then science. No one has a "perfect" design, or knows all the answers. You can use the general conclusions from this article to help your judgement, but always try the canoe out on the water, configured the way your most likely to use it. Don't be reluctant to try one that's a "little" different! My next canoe will be similar to #3, but just a tad asymmetric. Not because the computer says its good, I just like the way it looks!