Opinion: The Science and Magic of Boat Design: the Extasy

by designer Sabrina Barm


Modesty may be a desirable quality, but it doesn’t take you far enough in all situations. Rewriting rules and living your dreams boldly can!

The Extasy, of course, is a boat. The description reads a creeker and river runner for small paddlers, designed for enhanced driving performance. And it is so much more than that. It is a wild dream, a coming of age story, a celebration of the sport of whitewater open canoe, a message to live your dreams to the fullest, to be as bold and intense as you want to be, and:


It is my declaration of love to the river!



Fournel, France, testing everything – even the airworthiness

There were two motivations for designing the Extasy. 1) I had developed a new design method for whitewater canoes; and wanted to prove the theory works and 2) I wanted a boat to exist that allowed even small paddlers to have a “wonder weapon” for having as much fun as possible and pushing as hard as possible, too, if they wanted it.

There is a great variety of very good boats on the market, however all of them are designed by and mostly paddled by big, male paddlers. It is extremely difficult to estimate how something works for a physique and anatomy that is very different than your own. So it is not surprising that for people who are shorter and/or lighter than average, the conventional hull shapes are not ideal. Mostly, the ergonomics are off. The gunnels often are too wide and far apart and in the way, and the boat is generally too wide. The so often praised “stability” is less important when the paddler is shorter and doesn’t have as much leverage. The additional width and length also cause drag and handling resistance when moving the boat, not to mention it makes it harder for a smaller person to tilt the canoe. It is like wearing shoes that are too big for you.

I believe, that the only reason why smaller persons, especially women, have not complained about this more is that nobody has had something to compare to. They have not had a chance to experience how a more agile boat can improve their paddling and overall river experience.

Hull speed, another aspect of design, has often been said to be not as important as “stability”. This may be correct when you can muscle your boat through anything but how does it work for people who do not have this strength? Here we can make the case for a fast hull with light driving and handling resistance. There was a need for a boat offering speed and precision without requiring much effort and still providing a sense of stability/safety in bigger, more aggressive whitewater.

With everyone saying a boat can either be easy to paddle and stable, OR high performance, Is this design possible? Under certain prerequisites, I believe the answer is yes.

CAD shot
shapes that appear unusual – but proved very, very functional

My history is one of canoe slalom and downriver racing, fields where performance, precision and speed are key. Yet, a super fast boat that flips every minute won’t take you anywhere in whitewater racing, even if you’re a pro athlete. So, a good balance of boat driving characteristics also is key. University gave me the opportunity to try it all out. We launched a project that was about the structural and hull shape development of a slalom C1. For rewriting the geometry, we developed a parametric design approach and systematically tested the different options, both in fluid dynamic simulations and in experiments. This gave me a good feeling of how to fine tune boat geometry depending on which driving characteristics are wanted. The prototype in this project proved that our team had succeeded. We had designed a boat with great performance features while keeping the boat easy to handle.

So, can you have it all? Science and a methodic approach can help you a lot. Whitewater boat design is a bit of both science and magic. You can’t make a design that is equally great for every type of river, every paddler size and every paddling style however, have a clear list of pre-requisites: for a specific type of paddler (here: small paddlers) and a specific type of use (here: creeking, small to medium volume rivers), it is indeed possible. Maybe not to create the perfect boat, but to unite high performance and easy handling.


NOTE: when referencing small paddler, we were setting a design mark of 1,70m (5 ft 6) and 70 kg (155 lbs) and smaller. However, the Extasy has proven to perform well for people up to 80kg.


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