Choosing a sea kayak for your needs
a bit of explanation on sea kayak design

Every week I get a lot of email from people who want this or that in a kayak.  It is often the case that they have picked up a lot of bits and pieces of kayak design information and now know just enough to be either hopeless confused, or fixated on one particular aspect of design without fully understanding the tradeoffs involved.  I decided to put together this article to give a simple introduction on how length, width, and depth interrelate.  In the future, I hope to add another article on shapes.

It is often the case that people overestimate how fast they travel in a sea kayak, or how fast they need to travel.  I start by saying this because how fast you need to go will influence your kayak choices more than any other factor.  You need to make sure your boat is long enough that it can travel at your target speed and a little more without hitting "hull speed"  (hull speed is when your kayak catches up to it's own waves and can't go much faster).   However, it's easy to be overly concerned about hull speed, and as a result buy a kayak with a much longer waterline than you need.   There are a lot of downsides to a long waterline, generally the more waterline a kayak has, the more WETTED SURFACE it has, and the more wetted surface a boat has the more drag it has.  Long kayaks look really cool, but they also drag around more wetted surface and take more energy to push at normal cruising speeds than a shorter kayak.  Shorter kayaks are easier to push, easier to manuver, lighter, more stable, less affected by wind, and easier to fit in your garage.  So, contrary to popular sentiment, what you really want is the shortest kayak that will allow you to hit your target speeds without hitting hull speed for that waterline.

Sixteen feet is a common waterline length for a touring sea kayak, this will allow a strong paddler to cruise at 5 miles per hour, it also adds a lot of volume for camping gear.  However, I have found that most people aren't doing multi-week trips at 5 miles per hour.   A much more common use of a sea kayak is day and weekend trips at 3-4 mph.  For this sort of use a 13 foot waterline will be more efficient and feel faster, and be more fun to paddle.  If you want to test this a gps can be used in conjunction with a heart rate monitor to calculate calorie for calorie efficiency.  I am not an athlete, but I am a strong paddler, I paddle 3 times a week and I have never exceeded 4.5 mph under normal cruising conditions, even when paddling with strong friends or trying to set personal speed/distance records.  My average cruising speed is 4 mph. (3 mph upwind, 5 mph downwind.) My average cruising speed with mixed groups is 3 mph.

What about width?  Breadth is helpful to spread some volume out to the edges of the boat so there is something holding you up when you lose your balance. Width adds stability.  Personally, I really like a bit of stability for rough water and fishing and eating lunch.  But isn't a narrower kayak faster?  Well, yes, but not as much as you'd think.  Skin friction (wetted surface) and hull speed (waterline) have more to do with speed and efficiency.  Narrower widths really comes into play in racing or fast touring.   Racing and fast touring is hard work because DRAG ISN'T LINEAR.  Every mile per hour faster you go takes TWICE THE ENERGY OF THE LAST, due to the increase of turbulence in water moving across the hull.  Essentially the faster you go, the less you speed you gain for how hard you have to work for it.
This is why I prefer to design boats for 4 mph instead of  the usual 5.  To me it doesn't make sense to me to paddle twice as hard to go 20% faster, or to pay the penalties in windage, wetted surface, stability and manuverability.    However, for those who need the speed, in these conditions where you have to expend huge volumes of energy to hold your speed, every little thing helps, narrower is a little faster, and more importantly, narrower allows you to get your paddle planted closer to the boat giving you more push per stroke.  Of course you sacrifice stability, and it's worth it, AT THOSE SPEEDS, but at normal cruising speeds, the gains you achieve from making a kayak a few inches narrower are minimal and don't outweigh the losses in manuverability and stablity.  There is a way to get the best of both worlds, by making the kayak with flared sides you can have a narrow waterline AND a lot of stablilty when you need it.  A shorter sea kayak with a narrow waterline is a very quick boat indeed!

Depth and width combine to add stability.  Shallow and wide just lets water flood over the gunwale, which REALLY increases your wetted surface, so if you are going to wide, it makes sense to go deeper too.  Depth also gives you room to pack gear, and it lets you raise your knees.  The knees up position is more comfortable, easier on the back, and is better for delivering power to the boat.  Low back decks are popular right now for their ability to allow super easy rolling, but an ultra-low back deck that is constantly awash slows you down and messes with the kayaks' handling, it is also a liability in rescues scenarios. Serious greenland rolling demands a boat like this to accomplish the very hardest rolls, but for all of the beginning, intermediate, and even some of the advanced rolls, an ultra-low back deck is unneccessary and will only instill bad habits as it allows you to flounder upright with terrible form.  With good technique you should have no problem rolling even the most unwieldly barge of a kayak.  There is nothing wrong with owning a super low volume sport rolling boat, they can be very fun but will not make good cruising kayaks.  It is interesting to note that very few actual hunting kayaks had ultra-low back decks.

What about the rest of design?  I'm not saying that width, depth, and length are the only things to look at, but these are what many people fixate on and by looking at them first you identify a starting point to give you an idea of what sort of boat you might be looking for and then you can try different boats in that range to see which one works best for you.  Every choice is a tradeoff, but the more you know about kayaks, the more informed you'll be to actually be able to make those choices instead of letting marketing or fashion make them for you.  Personally, I paddle my F1, it's 14 feet long and 23 inches wide and allows me to paddle VERY easily at 4 mph.   I like the feel of my LPB (16 feet long and 22 inches wide)  more on flat water.  The ergonomics are a little cleaner and the sprint speed is pleasant, but over long distances, the increase in wetted surface means that I am NOT any faster.  In rough water I much prefer the F1 because it is utterly unaffected by wind, super easy to manuever, loves to surf, and is rock solid stable.  The kayak is more than just a set of numbers and drag coefficients, it's a work platform, and I can tell you from experience that 'faster' longer boats really slow down when they are fighting the wind or are capsized.   I'm not saying the F1 or any other short boat is the right choice for everyone, but it's right for me.  If I were a strong fitness paddler on calmer waters most of the time I'd probably chose a 16 foot boat.  If you can get in a boat 3-4 times a week and really push, you'll get the body you need to make a 16+ foot waterline really sing, otherwise think about going shorter.  An exception to this is for people who will be doing a LOT of sea kayak camping where the extra length is helpful to add room for gear.  Still, for week long trips or less, I simply carry a lighter kit.  My freinds are all in 55lb boats with 75 lbs of camping gear, I'm in a 28 lb boat with 35 lbs of camping gear and due to my shorter waterline and lightweight, I have...(to hammer the point home here).., MUCH LOWER WETTED SURFACE, which is why I can keep up just fine despite my shoulder injuries.

What about hunting kayaks?  Inuit kayaks are fascinating and what I've written applies to them as well, what is different is how much it mattered to the inuits.  As recreational paddlers we tend to focus on how easy a boat is to paddle, how stable it is, and how it handles in the wind.  We pay much less attention to things like little splashing noises that would cause a kayak hunter to starve.  Many people are surprised to find hunting kayaks somewhat challenging to paddle, and they look at these boats as though they might benefit from 'improvement'.  It will greatly increase your appreciation of a traditional kayak to accept it for what it is, a hunting tool, designed above all to bring as much meat home as easily and safely as possible.  When you slide into a hunting kayak you go on a cultural journey, and you'll enjoy that journey more if you let the kayak be what it was designed to be.

Racing kayaks?  I'll touch on this briefly by saying that you give up almost every other favorable aspect of kayaking: stability, seaworthieness, cargo room, efficient touring speeds,  in pursuit of the ultimate top speed.  Racing kayaks are sexy and alluring, but they are also easy to find used for a reason, people buy them and realize that they are unpleasant to paddle.  For serious trained athletes, the drawbacks of a very narrow boat and a long waterline are a necessity, for everyone else, I say leave them alone.   Another consideration is that once you surpass a certain length to width ratio, you kayak is considered an unlimited class racer, and when you race you will be competing against VERY strong athletes.  If instead you choose a kayak that is on the edge of this classification, you can enter in the sea kayak class where you might have more fun and a much better chance of placing well, and you'll have a kayak that is actually useful for doing other stuff.

I hope this helps you choose the best kayak for your needs, whether you buy a boat or build one it's important to remember that just because a boat is fashionable or common doesn't mean it's the right boat for you.  Kayak designers make kayaks that will sell, and kayaks that sell influence the kayaks that people use and buy.  It has become common place that a sea kayak needs to be 17 feet or longer to be taken seriously, some designers are finding sneaky ways around this.  I've noticed a few of the hottest new designs have much shorter waterlines, with long ends that stay out of the water most of the time.   When I asked one designer about the purpose of these ends he confided (paraphrased) 'We have to sell kayaks.'

Kayaks I currently own:

Sea Kayaks: 2 of my F1's
Racing kayak:  My Tyak
Hunting kayaks: My Disko Bay IV-A-375
Whitewater: 2 Necky Jives, Dagger CFS, Liquid Logic Jefe, Jackson Rocker
Squirt/Surf:  Mega Venon, New Wave Vulcan

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