I posted this at the bottom of the wilderness systems tsunami thread but thought it was interesting enough to get a good discussion going…
this comes from the kayakacademy.com website…
http://www.kayakacademy.com/seakayak.html
Length, Waterline, Tracking & Maneuverability
“In my opinion, long sea kayaks are over rated. The longer a sea kayak is, the less efficient it will be at typical touring speeds (say 3 to 4 knots). Some long time paddlers will need to read that again. There is a common half-truth in the world of sea kayaking that longer boats are faster, and this is so deeply ingrained in the heads of many sea kayakers that they can’t understand why they have a hard time keeping up with friends in shorter kayaks. Some of these misguided folks have even gone and bought kayaks that are longer than their last one, only to find they have even more trouble keeping up. The problem is people tend to assume that a kayak with a faster hull speed (top end potential) will also go faster at half throttle, however, the opposite is generally the case (when comparing boats from 14 to 19 feet long). A monster truck with a big engine may be able to go faster than an economy car, but which could go farther on a given amount of fuel? And if it were possible to measure the rate of fuel burn when both vehicles were cruising at 70 mph, the big truck would be the less efficient one (working harder to go the same speed). If you rationed the big truck to the same amount of fuel per hour that the economy car was using, then the truck would end up being slower even though it has a higher potential top end speed. In the case of boats, the longer a boat’s waterline length (the length from where the bow meets the water to where the stern exits the water), the more surface area is in contact with the water (wetted surface area). And at the speeds most sea kayakers tour at, most of the resistance holding you back from going faster and making you work to maintain your pace is the friction of water sliding along the wetted surface area of the hull. The more wetted surface area your hull has, the more friction you have to overcome. So if someone barely has enough power to keep up to their friends who are just cruising at an all day pace, putting this person in a longer kayak (with its greater wetted surface area) will just slow them down even more. Conversely, it often helps the group go faster if they swap boats so as to give the weaker person a shorter kayak (provided the shorter kayak isn’t also wider or poorer handling etc.). From here on please interpret “length” to mean the waterline length, as comparisons of length overall are meaningless (except when it comes to fitting a kayak in your garage)…”
and also:
“So if a longer kayak won’t necessarily make you go faster, what about the other “advantages” to long boats? Another common misconception is that long kayaks track (go straight) better than short ones. While there may again be a some truth to this (though maybe in this case it is more like a tenth-truth than half-truth), the more significant factor is the shape of the hull rather than it’s length. Some hull shapes track poorly no matter how long the boat is, while some short kayaks track just fine. Anyhow tracking by itself isn’t always a good thing. You want a kayak that makes it easy to keep heading the direction you want it to go, and that requires a balance between tracking and maneuverability. If a wave, breeze, or current sets your kayak off course, the stiffer it tracks the harder you have to work to get it headed back on course. So you want a kayak that tracks well when it is on course, but maneuvers easily when it is off course.”
gotta admit it kinda pokes a few holes in what seems to be established thinking…
what was the question?
question?
there seems to be prevalent thinking that the longer the boat the faster the boat and the better it tracks. I thought this was interesting and worth discussion.
Do we have a new TROLL?
What is this, another new poster that won’t publish a profile yet starts asking questions couched in titillating phrases?!
Please introduce yourself and share with us your level of experience.
Nothing is simple
I think you’re gonna hafta demo and rent boats for yourself to find out what is too long and too short for YOU.
And what’s so bad about that? 
True for some
My wife, who's 5' tall and not a strong paddler, is faster and more comfortable in her 14' Tchaika than she was in her 16' Avocet. But there are other factors -- the Tchaika is also narrower, has less freeboard, fits her better, and is 20 pounds lighter.
On the tracking side, I can outturn some shorter rec boats because I can get the Avocet up on edge and make it spin. You can't do that with a short, straight-keeled flat-bottom boat.
Personally, I think folks worry too much about length and not enough about the the other factors that make a boat "work" for a specific paddler and their mission.
troll?
I don’t think so. I did post my profile and my level of experience as a beginner. If trying to glean as much information out of the expreienced people, coupled with reading extensively and trying to educate myself in not only boat lengths, but safety, safety, safety, and by tring to contribute by bringing up interesting and thought provoking comments that really do make one think is trolling, then I don’t know what to tell you. Prior to accusing, perhaps you should ask?
It Doesn’t Poke Any Holes Really…
You have to look at length and volume as relative to the individual paddlers and not at these factors as stand alone. The "efficiency" of the boat is matched to the skill, strength and endurance of the individual paddler.
I will tell you outright that I can easily cruise at 4-4.5 MPH in my 17'x18" skin on frame. This is my "ocean boat." In my 14.5"x 23.5" Mystic, I am hitting the wall at near 4 MPH. The Mystic is climbing over it's own bow wake fighting me every foot of the wave after 4 MPH. In a strong head wind, over 25 knots, I thought I was going to bail out of a final trek in my Mystic. I was going only about 1.5-2 MPH. What takes me only .5 hours even in similar headwinds in my SOF, took at least twice as long in the Mystic. On the final leg of a trip, that extra challenge could have been a bit much. If I didn't have a bail out route, I could be have screwed if I really needed one against a strong offshore wind.
sing
You're reading too much and not demoing enough.
thanks angstrom
that was the type of commentary I was hoping for. I was looking for some validation to this article as it is overwhelming the consensus that long is better. I was accused of trolling previously…I apologize to anyone who thought that. I am simply trying to learn and I have little respect to those who jump to conclusions. If I did that, based on the comments on the majority of the forums, I would have a 19 foot boat!
sing
your last comment hit home…will be back after demoing.
Thanks
“Demoing” (is that a word?) is essential
As Sing suggests, paddling as many boats as you can find, in as many different conditions you can get into is really the only way you’ll find a boat (or boats!) that will work best for you.
Many of us, myself included, spent a great deal of time reading all we could about boats when we were first getting into paddling, but without even more paddling than reading at that point, all that reading can confuse and confound you more than anything.
As I mentioned above, if you can try different boats out in varying conditions, you’ll get a much better idea of how each boat handles than if you always try out boats in one type of condition (calm waters are only good for seeing how a boat handles calm waters, etc.).
I was very fortunate when I first started paddling, in that I had access to three different rental shops, with a huge selection of different boats to choose from. I also had all day, every day, for three months to paddle all these boats. In these three months, during which time my skills developed a bit as well, I was paddling all these boats in plenty of wind, swell, and even some surf. By the end of this intensive “demoing” period, I felt very comfortable when I made my choice for my first boat purchase, which happened to be a Current Designs Caribou (before they put skegs on them). I have another boat now as well (and more building projects planned), but I still really love to paddle the Caribou in any condition the sea can present to me (well, within “relative” reason, that is; though I have been accused of being a bit crazy at times, yet I’m still here to do it again and again!).
Paddle lots of boats, and eventually, one will say “I’m yours!”, and that’s when you make your first choice. 
Melissa
Absolutely…
when I built my SOF, the dimensions didn’t come out of the air, or what was suggested by Morris’ in his book. It came from already having and paddling a Loon, Pamlico, WS Capelookout, CD Squall and Impex Montauk as well as Greenland S&G for several years. That’s why I think my SOF is darn near perfect boat for me, with the attributes that I want (especially after a reskinning a change to the deadrise and rocker).
sing
Everything is a trade off.
If you take a 13' kayak & stretch it to 14', you would notice more speed increase than if you stretched an 18' model to 19'. At some point the long boat does not get any faster, only harder to portage, car top and requires more room for a 180 turn. My 21' yak is only slightly faster than an older 17'& 19' model. My 13'10" is just under 3 mins per hour slower than my 14'9" downriver, yet, my 21' is only 3 mins per our faster than my 14'9". All of these boats do fine at a cruise pace. You notice length most in the shallows. When I switch from my 21' to my 14'9" or 13'10", (especially in shallows) it feels like some one is holding on to the grab loop! Good luck & try everything you can.
If you had posted a prifile
then there woulf be a likkl “head” icon next to your name. and this is your second post on kayak length.
get out paddle meet paddlers who seem competant. ask these folks go used for your first boat or two, the when you know what you want, if big bucks are the only way to get it well…
I’ve got a few boats
and i go about sea kayaks with a different angle altogether…i’m not willing to invest the cells or time nec. in attempting an understanding of hull theory/mechanics/speed/efficiency and whatever.
To me sea kayaks are works of art, beautiful structures, and for me one of the greatest pleasures in life is gliding in one after taking a stroke. I’m trying to build a collection for the girls to fight over after i’ve passed and can only hope that when they look at any individual boat that they appreciate the artistry of the 'yak and not nec. which one is faster or most efficient.
I also get excited about each aquisition, whether it was the QCC a couple of weeks ago or the CD Kestrel that is in route. I love to get in a different boat every other day–the beauty of living 50 feet from water on a small private lake—I truly enjoy the merits of each boat and can enjoy an hour in a Perception Acadia lazing about the cove watching the deer swim, or 45 minutes working out in the Looksha II.
There is no perfect boat though many of us including myself will rate a boat a 10, and i’m glad there is not that one do everything boat, it allows many designers to explore the possibilities and old farts like me to enjoy each expression.
I am asking. Thanks!
So what are you paddling these days?
profile now visible
well I thought it was public…didn’t really pay much attention to the little button on the bottom…was too busy trying to learn stuff instead of delving into people’s credentials.
thanks to Peter K who pointed it out to me.
That prevalent thinking is correct !
Don’t try to fight it.
Cheers,
JackL
yeah
but Long boats just look COOL… and really thats all that matters anyway… L
To answer your question then,
and thanks for telling us a bit about yourself, size matters. Size, length, width, height AWL, length AWL, weight, hull shape, hull integrity, ad infinitum.
The opinion you shared with us in your post is just that, another opinion. A lot of good points but this whole size, length, sea kayak, rec kayak thing is totally up to you and what you plan on doing with the boat you acquire and what you plan on doing to train yourself for it.
If you have a particular boat or type you want feedback on give us a shout. Your 10 foot rec boat is good for many things. All boats are good. Getting out there and enjoying the sport is reason enough. Knowing the model would help us determine where you are coming from. Knowing what you want in your next boat will help too.
You mention established thinking and how one opinion “pokes holes” into it. Not really. Long is good. Short is good. Medium is good. There are givens with coefficients and the variables are all over the place. The paddler, the hull, the sea conditions, the paddle. What do you want to know and how can we help?