OK, this one is something that has come up a couple of times in conversations I've had recently so I figured I'd put it out there and see if we can get some involvement. I am effectively a beginner in terms of understanding the ins and outs of what makes a kayak fast. I have some vague understanding that lighter stiffer material gives less resistance, that wake creates drag, that length somehow increases efficiency to a point before just adding to the wetted surface area and creating more drag. I also understand that there are external factors such as weather conditions, paddles, individuals' abilities, specific application, etc...... I understand all these things exist, just not whether a ski is faster than a K1, how a boat can be faster than another but only over long distances, where UR boats like mine fit into the mix, etc.

As a complete beginner, the best advice I received was from Scotty and Patricia and that was "a boat which is so tippy you can't paddle it is not fast for you no matter what it will do for someone else". Also "get in and try as many as possible to figure out what works for you". And finally, "figure out what you want to do with your boat and get one that suits that activity". OK, so those quotes probably aren't word for word but you get the idea.

So tell me, how are boats generally graded in terms of speed assuming they are all performing in the same conditions with the same paddler, using the same paddle etc.?

Justin,

Here's my take. This will probably start a war, but here we go:

First the physics. When you push a boat through the water two things slow it's forward momentum.
1. Friction from the water against the the boat.
2. Pushing the water in the way of your boat out the way.
You'll notice that I haven't mentioned air resistance or the hole created at the end of your boat. Both of these can be effectively ignored because they are a different order of magnitude. I also haven't mentioned weight. It's a minor factor when you consider my big butt.

Your friction depends almost entirely on the wetted area (the area that gets wet) of the boat.

Pushing depends much more on the shape of the boat. Boats which are more vertical tend to push the water sideways rather than down. Sideways is better because you don't have to compress the water underneath you, instead you can form waves at your side. A smaller cross section of the boat means that you will push more water sideways-sideways, rather than forward-sideways (which is effectively paddling uphill).

So here's my take:
Pat and co are right that you should choose the right boat for you. I'm not going to cross the tasman in a TK, because I can't swim that far.

So lets assume a hypothetical perfect paddler, on perfectly flat water, in a boat which is suited for them. We'll leave out the hobie's and play boats and that sort of thing.

From fastest to slowest I would say:
Sea Kayak
TK
Ski
K1

Of course, you will get some overlap. The fastest sea kayaks may go faster than a TK from the 60's or 70's. The overlap is probably even closer at the Ski and K1 level. I still think that the fastest K1's would beat the fastest ski's. Here's my reasoning:
Friction - longer boat, more friction. Ski not quite as quick. A longer boat gives you more opportunity to create a thinner boat with the same volume.
Shape - A ski has quite a low angle for most of it's length, better than a K1. But your ski is normally wider at the widest point compared to the latest K1's, for one simple reason. You sit in a ski (yes I know you sit on a ski, but the line from the bottom of the ski to it's side is usually one curve, while in a K1 it is two curves), while you effectively sit on top of a K1. There is also a slight leverage advantage with the higher seating position.

Having said that, for me, who is above any of the weight reccomendations for a K1, I'm probably better off in a ski, because of the profile. I just don't like the low seating position.

On the better for marathon paddling it's less of an issue. Some boats may be more efficient at particular speeds (the 8-12kph for marathon) vs 12+ for sprint, but I don't personally thing there's a lot of difference unless you have the kind of money to spend that I don't.

If you want to try out a K1, let me know and I can get you started, and you can find out for yourself.

Russell

I've noticed when paddling a TK that it performs fairly well into the wind, ie I can often stick with 'faster' kayaks, but I'm easily dropped going downwind. The TK also bogs down in shallow water when compared to other 'longer and slimmer' kayaks. A race at low tide in windy conditions at say Narabeen is not good for a TK. Compared to a K1 the TK requires constant effort to keep one's speed up. As soon as the power diminishes the TK falls into a hole whereas the K1 seems to glide almost waiting for the next power surge. JP

I was recently searching through adventure races and found an anaconda site that has the results of a full study, that interestingly, had Margie's name all over it. It is pretty heavy reading but really informative in comparing like boats with like boats.

www.rapidascent.com.au/asp/KayakTestReportII.aspx?e=2

If you get a chance corner Margie on the tests....

That's awesome thank you guys!

Daryl,

That was the repot I was thinking of. In terms of the engineering and science behind the workings of kayaks and what makes them fast, it is an awesome write up. Clearly margi and the others working on those aspects were exact and thorough in their approach. Given that's what this post is all about, it's the perfect answer.

As a side note, I find the write up of other aspects of the kayaks' performance (comfort, layout etc.) less than useful. The likes/dislikes sections give no context around which paddlers (or type of paddlers) made the presented comments. We are left with several contradictory comments about several boats and no way to sensibly use that information.

But, as I said, for the "which is the fastest boat" question, an awesome report.

I would love to see how the new V12 tracks if they do it again. Perhaps Scott would donate his new one to the cause

Have fun!

Guys,

I also noted that earlier in this discussion John referred to his boat slowing down in shallow water.

The phenomenon that causes this is referred to as 'vessel squat'. Quite literally any displacement vessel (canoes don't plane unless you are an absolute superman) will pull lower into the water if it goes into shallow water.

Below is a link to the wikipidea explanation:

en.wikipedia.org/wiki/Squat_effect

As a general rule the amount of squat that is experienced is dependant on the width of the bow of the vessel. The wider the bow of the vessel, then the depth of water at which squat will occur will be more that that of a vessel with a very narrow bow. (By bow I mean that area of the boat that initially pushes downward)

I'll let you work out the rest!