The science of boat sizing

February 14, 2006

I was asked today by a customer if David Knight and I design each size of boat separately or scale them. It is important to know these things before you buy one size kayak and hope it performs like your friends kayak of the same model but different size.

Most companies design a completely different kayak when they make a different size. You can see this in their designs. One size of their kayak paddles different than the other, and could easily own a different name. The question is which one paddles the best?

There is one thing that David Knight and I have down to a science. That is proper sizing of our boats, and maintaining the performance goals across the sizes to achieve the same boat in each size. There are a number of physics laws that can be applied to sizing of kayaks, that still allow for proper ergonomics, and it is still possible to make a boat that Dane paddles or a 240 pounder paddles and have it be the same boat for both people. Many factors are not a linear scale and applying a linear scale to them would not work. Remember those pesky expediential equations that are so prominent in kayaking, like moment of inertia, leverage, etc., etc.. People don’t scale linearly either, with Dane at 4’5” and 67.5 pounds, and me at 5’6” and 160 pounds as an example (25% taller and 250% heavier) Each Jackson Kayak is designed for the performance characteristics that the style of boat is for. Fun (easiest to roll, great downriver, great surfing, carving, squirting, etc.) and then the challenge is to properly fit the body range that the size is designed for into it, and then once the ergonomics are met, the features of each boat are scaled to perform for that size range of paddler, just like the other sizes. This is what we think works best. Dane, Emily, and I can all paddle a boat with the same name, and know that what that boat does for me, it does for them. If that isn’t the case, then one of us is in an inferior boat, and that doesn’t fly for me.

The bigger picture of this whole thing isn’t just how Emily’s Star compares to my All-Star or Jay Kincaid’s Super Star, but how the Star series compares to designs available from other manufacturers. This is where David and I feel we excel the most. While we know that we can improve upon our designs, and have done so in each generation of design, we are focused on outpacing the competition, and going for a design that will be the best in its category, even after our competitors create their own version of it. That is another subject, but I prefer that you simply do the Pepsi challenge with our boats, instead of hearing it here.
🙂 EJ