Flat bottom kayak paradox?

Riddle me this, Experts: Wolfgang Brinck, famed teacher and builder of SOF native kayaks, referenced articles on flat bottomed East Arctic kayaks. Having just read these, I’m blown away by what they state. They describe long, flat bottomed kayaks used by the Inuit for sea hunting that are purported to be BOTH very stable and very fast!

That is contrary to the conventional wisdom posted here (and everywhere) that you can’t have the initial stability of a flat bottom and the speed and handling necessary for open seas. Hmmmmm…

Is it possible that modern kayak theory and design settled in too fast on only one form factor?

Does anyone have any more info and especially experience with these types of craft to share?

Can you share the link to these articles?

And the width of these boats was?
Gotta ask - often the native boats were narrower than we realize.

A flat bottomed kayak can be fast,
relative to many of the kayaks you’ll encounter in a day of paddling.

But the physics of boat design are immutable, and when you give a designer like John Winters the length and width of the native kayak you describe, and he’ll hand you back a kayak with a shallow arch bottom and a bit of rocker that will walk steadily away from native designs.

As for stability, that depends not on flatness, but on the sides of the kayak, and what happens with those sides as the kayak tips. I have an old Noah Magma kayak, flat bottomed, and surprisingly fast. But it has very low initial and secondary stability, because the sides are canted inward, and don’t add stability as the boat tips to the side.

Not sure how flat you mean.
My NDK Greenland Pro has a real shallow V which is rather flatish on the bottom yet is pretty fast kayak especially with following waves. Its a hard chine kayak too. Not sure exactly what shape your talking about but iam interested in reading this info. Any link?

be interested to see the link
I would also be interested to see the link to see what it really says.

You say “purported to be BOTH very stable and very fast!”, and then talk about “the speed and handling necessary for open seas”. Are you making an assumption that speed and fast also includes handling for open seas? Or was this specifically talked about in the article? Not all areas where kayaks were developed were open/exposed waters.

Link, etc.
Let me clarify that what I read everywhere says that open seas require higher secondary stability, not speed, which is supposed to be a trade off with initial stability (usual in flat rec hulls). The speed was a second issue, which is also usually not correlated with flat hulls either.

Here’s the link to Brinck’s Skinboat Journal in which he lists some articles: http://skinboatjournal.blogspot.com/2013/11/flat-bottomed-kayaks-of-eastern-arctic.html

Brinck is a very experienced SOF builder out here in SF Bay, teaches building, wrote the book on baidarkas, etc. He wouldn’t be easily taken in. The authors of some of this work are also respected arctic native ethnographers.

I’m not making the claim, just curious about whether the industry has missed something that might be very desirable.

As to fast, it’s not an issue of racing, but being reasonably efficient, so theoretical hull speed isn’t as important as real world utility.

In fact, wider!
Or so the articles indicate.

maybe sides
If I read the articles correctly, these were not narrow boats.

Talk to Harvey
If he has already built a replica he has paddled it. And since he has built so many replicas I’d bet he can provide some insight regarding various design trade offs.

He has built it.

– Last Updated: Nov-23-13 10:27 AM EST –

Labrador Kayak: 22'7" Long, 24+3/4" wide.

(Not all that narrow, but length improves a flat bottom's waterline. "Speed" therefore, is again...relative.)

Note also, very pronounced "v" entry bow changes the whole dynamic--Not a total flat plane from stem to stern.

I don’t believe in pardoxes like that

– Last Updated: Nov-23-13 11:23 AM EST –

Everyone knows I'm no kayak expert, but the "cause and effect" attributes of design often interest me. I'm only posting because I don't believe in ancient magical mysteries that are beyond the understanding of modern scientists, in this case, the scientists being today's experts in hull design and fluid mechanics.

When the attributes of these boats are all judged as subjectively as this (in this case, much more so by the original poster than by the author of the article), my gut instinct is to chalk off any conclusions about the contradictory qualities of these boats to the tremendous overlap in capabilities between related designs that we all see, and to the concept of "degree of acceptable compromise" we already know is necessary when rating/choosing any style of boat.

I quickly perused the article and took note of the fact that the boats were quite broadly flared for the purpose of carrying heavy loads. You'd automatically get your secondary stability from that feature. The article actually provided a way of quantifying that hull profile in your mind. The typical hunting model was 24 inches wide, but since the flattened bottom of the typical hunting boat was 16 inches wide and that would be well below the surface, especially when carrying the maximum load, you can see that even if the "bottom of the bottom" was flat, the overall profile of the submerged portion of the hull was far from it (more like a chopped-off "V"). I seem to recall that the Phoenicians used the same concept - hulls that were narrow and speedy when empty but wide and stable when loaded, but even if that's incorrect and it wasn't the Phoenicians who did that, it IS a design concept that's well understood and used a lot to this day, so there's no paradox here either.

It was also mentioned that once the people using them stopped throwing harpoons and started killing their prey at great distances using modern rifles, they started making the boats even wider because a slower boat was now suitable for the job, and I see no paradox regarding that line of reasoning. In fact, it makes me think that they really knew the same things modern designers know. It makes me think that their previous versions were already designed for load-carrying but that that aspect of design was not taken to such an extreme that they became "too" slow. In other words, this design change with the acquiring of rifles suggests to me that they also knew how to make boats that were even faster, but that the pre-firearm models which needed to be able to carry a heavy load were not paradoxically fast, but "fast enough".

Also it was mentioned that they were not used individually in rough water, but would be tied up in groups for safety, so there's no paradox about sea-worthiness either.

Someone else here mentioned that hearing from someone with direct experience would be the thing to do. I think it also helps to note that the author himself said things which support the idea of design compromise much more than paradox.

Two designs
one with a rounded bottom and one with a flat. The width was given in CM, but when converted, 21.5 inches, at the small end is in line with greenland kayaks. At the wide end (31.5 inches, give or take a smidge, is a fairly beamy boat). Sadly, the diagrams don’t give us much of a comparative cross section, so it is difficult to discern which designs were at the widest end of the spectrum.

One thing I did notice, also, was that the flat designs were well flared out and had a much wider deck than bottom. This should help with secondary stability (similar to the USS Monitor design http://tinyurl.com/lq3r9dy ).

Another item to consider is materials. There is a lot of debate over whether a skin boat, being (relatively) more flexible could maintain speed better than a hard hull. The thought was that the flexibility (especially at the sides) enabled the boat to respond to turbulence along the hull better than a hard side hull which had to rebound any turbulence. The logic I was given seems faulty to me, but the essence is that you get shock absorbtion on the skin hull which reduces turbulence. Maybe. I’ve yet to see anyone test this.

I still have doubts that you can make a wide, flat hull perform as well as the article indicates. This doesn’t mean it isn’t fun to paddle, just that it will have those same design tradeoffs and will be slower, and less nimble, than narrower boats. One of the ways to offset width, however, is to expand the length, and I didn’t get a feel for how long these boats were.

It would be interesting to see, and paddle, these hulls. I’m sure most of the native designs were much more seaworthy than most think and would probably be a joy to test.


Today’s experts
"I don’t believe in ancient magical mysteries that are beyond the understanding of modern scientists, in this case, the scientists being today’s experts in hull design and fluid mechanics."

I just want to comment on this particular comment in the otherwise informative posts of GBG because I’ve read viewpoints like this before. I believe it’s true in general, but not as to the building of canoes and kayaks.

I’ve never met a modern canoe or kayak builder who qualifies as a scientist or expert in mathematical hull design or fluid mechanics. With the exception of John Winters, who is a formally trained naval architect, almost all paddle boat builders are primarily just guessers, eyeballers, tweakers and try-it-outers – backyard experimenters – just like their predecessors 2000 years ago. Except the guys 2000 years ago may have been more motivated because their lives literally depended on having the most functional hull designs.

Even Winters admits in various parts of his writings that it’s difficult to scale down many key naval architecture and hydrodynamic principles to small and slow moving hulls such as canoes and kayaks.

As to flat hulls and initial stability, I think those hull design attributes have been foolishly derogated and ignored for many decades in favor high hull speed – for what? – and the supposed superior importance of secondary stability over initial stability – for what? If the answer to “what” is racing or rough water ocean performance, I must point out that those are two relatively small worlds in the universe of recreational paddling.

Wider, flat-bottomed and highly initial stable hulls have made a nice comeback in the world of whitewater, and never really left the world of solo wilderness tripping in tandem hulls. These wider and more initially stable hulls also prevail in the rec kayak and SOT markets where hull function has nothing to do with winning races or circumnavigating


Not sure we disagree about anything

– Last Updated: Nov-23-13 1:21 PM EST –

I imagine you are right about most canoe/kayak designers being visualizers, guessers and tweakers. But even if the designers are working by the seat of their pants, I don't believe there are any design attributes which would defy explanation if scientifically evaluated, or even if looked at with the common sense of the average non-mathematical designer. My main point was that it can be more important for a boat to be pretty good at two or three different things than for it to be optimally designed for just ONE thing, and that simply being "pretty good" at two or three different things does not constitute a paradox.

I think there's a bit of apples-to-oranges stuff to be careful of though. For example, as to flat-bottomed boats becoming popular for whitewater, that's getting into a whole other realm of boat-handling goals, including such things as surface-planing against the current on waves and being able to let the current streak by during pivot turns without grabbing the hull no matter what the orientation. As to other special considerations of the flat-bottomed whitewater boat, I'll leave that to others with more experience, but in short, it's a whole new purpose for a flat bottom, not at all related to more traditional design for boats used to cover distance on flat water. However, your own statement that flat hulls have been put aside in favor of those having greater speed shows me that you are thinking along the same lines as I was when I figured that a wider boat that's "fast enough" might be "good enough" as long is it does something else reasonably well too. I interpreted that other attribute in this case to be the ability to carry a big load, and probably also "plain old stability", especially with some flare adding secondary stability.

And so they could not be very fast.
Like I said, immutable laws. If they’re wide in the water, they can’t be really fast.

Thanks but no thanks.

– Last Updated: Nov-23-13 8:37 PM EST –

You're making a lot of assumptions and it's uncalled for.
I was asking a legitimate question: Is there another design that fits what many paddlers might like?
Nothing magical here, and you took my word paradox to some extreme lengths. The natives lived or died by their craft, so they knew damn well what they were doing and they didn't need a computer to design them either. Trial and error was enough (you die if you're wrong so your design dies too!)
As to fast, did you read (or have you read elsewhere) the way hunts were conducted? Do you realize they had to accelerate really fast at times, or cover long distances loaded down in heavy seas? Those indicate that they had efficient craft, not just dumb floating barges.
Yes, I am aware that every twist and turn of a hull contributes to its handling characteristics.
I wasn't trying to get a heated debate going at all.

How do I reach Harvey?

Bjorn Thomasson, Sea Racer
Take a peek at Bjorn Thomassons Sea Racer, almost 20 feet long, less than 17 inches wide, flat bottomed, stable (for that width) and very fast. In his site he goes into his theory behind such a design. Hex

Bjorn’s design is not what I would call flat bottomed. I suppose, compared to a round-bottomed it is somewhat flattish… Scroll down to see the cross section.


More importantly, it does not have sharp edges on the chines. His, it is more efficient than the multi-chined skin on frame kayaks. I’ve built a somewhat flat bottomed skin on frame, designed for speed and good initial stability. Little flare, sharp hard chines around the cockpit, full waterline, etc. the kayak was fast-ish, but the sharp edges definitely created some added turbulence.

Here is the link to my design: http://youtu.be/VdQ0Y6xlu-4