i wonder why longer boats are considered more seaworthy than shorter ones. i have 14’ and 17’ boats, the 14s seem easier to manage (easier to turn and control) when conditions get wacky. what is it about longer boats that makes them favored for ‘sea kayaking’? just speed potential?
It’s all in the details. 
Actually that is just part of the answer. Hull design, width and rocker also come into play. Many shorter boats are also wider and therefore seem more stable. Whitewater & surf boats being very short can turn on a dime, but unless you are experienced with them they are not really “stable”. So when you compare length you need to take design into account as well. In very general terms a longer sea boat provides speed, better control in conditions and more room for your stuff. As people become better at edging their boat and improve their paddle strokes they have no problem turning/controling a longer boat. In fact the design of most sea kayaks allow you to move pretty nimbly thorough the water. You also have to think about the physical effort it takes to push a wider boat any distance. A longer (and more narrow) boat is going to allow you to paddle further without fatigue.
So that is a pretty oversimplified answer but it’s a start.
a longer boat…
…think of a boat’s length as a lever arm. A
longer boat, when undergoing “something” that
tends to take it off course, will deflect less
at the nose, and thus stay on it’s intended path
a bit better.
This is basically why large heavy aircraft
carriers can go faster than quick nimble
destroyers.
In touring, fast changes of direction usually
are not a big concern. Quite the contrary,
you typically WANT them to track well.
With a WW boat, you need immediate and reliable
course changes. Also it would be difficult to
fit a 17’ boat into a micro eddy that exsists
between rocks that are only 5’ apart.
A 17’ boat would broach and you’d probably die.
(And remember: maneuverability is intentional
instability.)
Typically, the farther apart the boats center of
pressure is from the center of mass, the more
stable the craft is, because it will try to track
truer. This concept can also be applied to the
work place: stability and efficiency is often
seen to increase the farther your chair is from
your boss’s desk.
seaworthy
Seaworthy, to me, means how does a boat handle in typical sea conditions: swells, wind, currents, confused chop, etc. An important parameter in evaluating this is hull shape. A flat-bottomed kayak is very “flat-water-worthy” because its flat bottom conforms well to the flat water. However, this same craft in swells will want to keep its flat bottom parallel to the water, which now is not flat, but at the angle of the swell. Think of a plank versus a log. In flat water, the plank is harder to tip, while the log spins with little effort. Now imagine the plank and the log broadside to an approaching wave. The plank is greatly affected to the point of maybe tipping over, whereas the log, in a sense “doesn’t care”. Now, the disclaimer: more skill (but less effort) is needed to keep a rounder hull upright in sea conditions. Most sea kayaks don’t have a completely rounded hull, as that would be too much of a balancing act (exception: many surf skis have quite round hulls because it is the fastest shape due to less wetted surface). Common sea kayak hull shapes are therefore a V-shape, a shallow arch, or some other shape not quite round but not flat. In a good, high performance sea kayak, a skilled paddler can be out in conditions, and with a minimum of effort stay upright simply by being flexible and loose at the hips, allowing the boat to do its thing with the water.
Length helps in “averaging out” the seas, just as an aircraft carrier gains much advantage by sitting on several waves at once. Also, tracking is better with added length. However, length will work against you when manueverability is needed. Some use a rudder to counteract this.
I own several kayaks, and the one I consider the most seaworthy is a Tsunami double (a washdeck kayak), paddled as a single from the rear cockpit. It’s 20’ long, 28" wide, with a classic river boat hull shape, and a VERY durable rudder. In this boat, I’ve been out in horrendous conditions and felt perfectly secure…it even surfs well!
So there are a number of factors to consider amoung which are boat length, hull shape, performance in wind/currents, etc. Also, let’s not forget the skill level of the paddler…s/he must also be “seaworthy”. To me, the bottom line is, when I’m out in conditions, how secure and confident do I feel in the boat I’m using.
Tony
"a 17’ boat would broach"
thats what i’m talking about. shorter boats are less likely to broach?
Let’s make sure we know…
…what each other means by broach. I mand a broach pin where the boats flips sideway and
the bow gets slammed upagainst one rock and the
stern up against another. Very dangerous. The
boat can fold, trap you, and you’d be in serious trouble.
Another definition for broach is just sideways
to the waves. This too can be dangerous because
you may go around like a widowshade that’s been
sprung. Usually, however, the worst that happens
is that you contribute to the amusement of your
companions who seem to think it’s funny as hell.
A 17’ boat is NOT going to fit sideways between
two rocks that are 5’ apart.
Two kinds of stability
There are two kinds of stability that matter in a boat. Primary is the tendency of the boat to stay upright when it is sitting flat on the water. That is, does it feel the boat wiggles side to side easily if you sneeze or turn to look at a bird. Secondary stability is the tendency of the boat to stay upright, or actually return to an upright position, when it is leaned over on its side. If you look at an issue of Sea Kayaker, there will be stability curves with each review of a boat.
Primary stability is fine on a pond or flat river, but if you are paddling in waves the boat will regularly be heeled over on one side or the other. In those conditions you want to have stronger secondary stability, so when the boat is sliding down the side of a swell heeled over at say 25 degrees, the boat will of its own accord return to an upright position as the swell passes under the boat.
The hulls of sea kayaks are primarily designed for stronger secondary stability and the hulls of recreational boats are designed for stronger primary stablity. So in waves, the sea kayak will be more likely to stay upright than the rec boat.
Length comes in after the hull design, and is an aspect of a boat’s design for stability, handling and speed.
Traditional sea kayaks are longer partly because they were intended as touring boats. They had to be reasonably fast and efficient for long days of paddling (in general longer waterline=faster), and had to be able to carry a lot of gear because people used them to actually go out on expeditions. Now boomers (like me) get full size sea touring kayaks and use them as day boats.
Rec boats, generally are shorter because the extra capacity and speed is not needed. Why stick yourself with hauling around 15 or so more pounds more boat than you need?
All that said - there are a lot more boats out there than there used to be, many of which are new designs that are exceptions to the traditional rules. And the skill of the paddler is always in play. There are a plenty of paddlers on this board that would be fine in difficult conditions with a boat that would leave me swimming, because they are much more skilled. The best thing to do is as always, try out boats and see how well your comfort level, the boat and the conditions all match up. (safely)
Celia
Tony, It’s not often
that I read a post on this site that is so well done in terms of conveying the big picture. Well said. I find my 7’ 10" HP surf kayak the most seaworthy boat I’ve been in:) I find that I don’t want to be in any kayak over 16 ft. for ocean paddling. If it’s flat then go for the specific fast boats. Two different sports.
So, you don’t mean a broach pin
like you gave Pat when you asked her to go steady?
Wavelength – I didn’t want to bring
this up, because I don’t know enough to discuss it fully, but the distance between wave crests affects how boats of various lengths will perform. My little 14.5’ Necky Looksha Sport will not be able to span longer wavelengths as well as a 16+ foot Looksha IV because when the ends don’t reach the wave crests, the boat tends to broach. This is true even though the Looksha Sport has all the characteristics of a sea kayak, and does not resemble a rec kayak in any way. Of course, when playing in the surf, the shorter Looksha can be turned and set up for surfing a bit more easily.
You have it all wrong…
…I woke up with a hangover and found myself engaged.
Distance between wave tops
in following seas - the tendency of the boat to stay straight or not starts coming into play as well. I went from a boat with NO rocker (CD Squall) to about a foot longer boat with some rocker (NDK Explorer LV). I’ve only paddled the LV for one season, but it took the first week in Maine to find following seas that changed my mind about the use of a tracking device (never dropped the rudder on the CD in following seas) and the best angle to traverse the waves. Which changes the level of concern about trying to match distances between waves…
While the Squall just sits on top of each wave with very little correction needed once you get her set up in rollers, even with the skeg the LV requires more attention. The rocker seems to give her a bit less glide, so there is more moment by moment adjustment going on just to maintain a consistent relative position.
But the LV loves taking waves at 30 to 45 degree angles, coming or going, while the Squall feels happiest taking them head or tail on at 90 degrees. So with the LV I tend to snake in and out of the valleys between on an angle, never really finding the spot where I’d have to worry about burying the nose into a wave if the period was inopportune like I had to look out for with the Squall.
If the purpose is surfing, then the length of the boat v. period of the wave may be more critical - I’ve not had the nerve to try the real stuff. But for allaround handle in rollers or unorganized waves like you get in ocean bays, there is so much that has to do with the way the paddler/boat combination approaches a wave…
Celia
Good observations.
sea worthy kayaks
Some really great posts about this topic. I’d like to add that in general, longer boats have two bulkheads and better hatches and are therefore safer and more sea-worthy. For years many of the rec boats in the 12-14 foot range had sloppy bulkhead seals and ill fitting hatch covers so most of us did tell pals you gotta go LONGER to get a sea worthy kayak. But now there are quite a few shorter kayaks with well built seating, thigh braces, bulkheads etc and I see that paddlers like the stability and seem to progress into good paddlers. Seen a good number buy skinny sea kayaks a few years back and go the opposite way and end up staying an "advanced beginner"forever. FIT is everything. I know I can go through most anything in a 13.5 foot kayak I own that is 23.5 in wide and fits me versus an 18 foot Brit boat I owned that I wallowed around in. I see petite paddlers in kayaks too big and long have a helluva time in waves and wind too.
Different impression of the Squall
I’ve paddled one of those since 2002 and have a very different impression of it. Though at first I took waves on at 90 deg. (just because a more experienced friend advised doing that), later on I found I usually preferred taking them at 45 deg. The waves just roll smoothly under the hull and the kayak maintains much more of its forward momentum. I like the slippery feel of the roundish hull when that’s happening. When taking them head-on, I get a fair bit of bow slapping and hobbyhorsing. This happens even when I paddle it loaded with camping gear. Inefficient and tiring, not to mention slower.
In following seas, the Squall is pretty well-behaved but it does want to broach at least sometimes. I have not found it to be the extremely strong tracking machine that you described.
Squall - Diff’s
Agreed that the Squall does a lot of hobby-horsing in taller, close period stuff when you take it straight on. I did have to remember to not wiggle around while we were both airborne - just like jumping a horse, if you land leaning on one side you’ll keep going that way once the boat’s “feet” touch the water.
I didn’t mean to say that the Squall won’t take waves on an angle. I just meant that 90 degrees was always where I felt I had to do the least to manage the boat’s stability. Note that this only comes into play in waves that are noticeable to start with, 3 feet and up. In following seas, where I had consistent rollers to come in on (a pleasant but rare event - things are usually more disorganized) I did almost the same thing I used to do to fake parallel skiing over moguls. I set her direction up on the top of a wave, where there was not much boat in the water to turn, and found that as long as I paddled with the rhythm of the waves the boat just sat and rode them in. Can’t say that I was ever arguing with strong crosswinds in these conditions - they were always on my tail.
At 45 degrees, I sometimes needed to lean into a wave that was whitecapping as the peak whacked the boat and splashed water under my armpit and into the side of my face. (drat)
However, with the LV the angled approach requires no attention from me until really it gets to really tall or surfy stuff - breaking waves over shoals you forgot were there, that kind of thing. This last summer we ended up crossing a river opening, going into 4 ft seas that were very close and steep. (dunno if I could put this on my tail yet) The only nervous part of the equation was the paddler - the boat was just fine, and really only needed me to stay out of the way.
But all that said
Squall - Diff’s
Agreed that the Squall does a lot of hobby-horsing in taller, close period stuff when you take it straight on. I did have to remember to not wiggle around while we were both airborne - just like jumping a horse, if you land leaning on one side you’ll keep going that way once the boat’s “feet” touch the water.
I didn’t mean to say that the Squall won’t take waves on an angle. I just meant that 90 degrees was always where I felt I had to do the least to manage the boat’s stability. Note that this only comes into play in waves that are noticeable to start with, 3 feet and up. In following seas, where I had consistent rollers to come in on (a pleasant but rare event - things are usually more disorganized) I did almost the same thing I used to do to fake parallel skiing over moguls. I set her direction up on the top of a wave, where there was not much boat in the water to turn, and found that as long as I paddled with the rhythm of the waves the boat just sat and rode them in. Can’t say that I was ever arguing with strong crosswinds in these conditions - they were always on my tail.
At 45 degrees, I sometimes needed to lean into a wave that was whitecapping as the peak whacked the boat and splashed water under my armpit and into the side of my face. (drat)
However, with the LV the angled approach requires no attention from me until really it gets to really tall or surfy stuff - breaking waves over shoals you forgot were there, that kind of thing. This last summer we ended up crossing a river opening, going into 4 ft seas that were very close and steep. (dunno if I could put this on my tail yet) The only nervous part of the equation was the paddler - the boat was just fine, and really only needed me to stay out of the way.
But all that said
Sorry for doubles
My mouse is started highlighting everything it passed over - sorry for the double (unplanned) posts.
What I was going to say to finish is that “seaworthy” is as much about feel as anything that can be captured technically. A lot of it just comes down to what feels comfortable for an individual, and that’s often in factors that go beyond the designed aspects of the boat. I’ve been lucky to have had two sea kayaks that I consider to be hugely seaworthy, but someone else could get into the same boats and disagree.
Celia
It’s complicated
As noted above, a boat’s seaworthiness is a complex evaluation.
My Elaho, which is designed as a playboat, has a lot of rocker and is highly maueverable. Many use this model as a surf boat. However, it is a pain in the neck when transversing dimensional seas in order to reach a destination. In rear quartering seas, one is always wrestling with the boat. My Aquanaut which is an ‘expedition’ boat has much less rocker, narrower beam and fully rounded chines. The Naut does not turn as quickly but is much more confident in challanging seas. Its secondary stability is excellent and it goes where I point it without a struggle.
On the tops of the waves
One situation where the Squall does not hobbyhorse AND makes for a fun ride is when both ends are supported by consistent waves. In a few such instances (it only happened when I was in Alaska), it felt like the boat was flying along on only the white water and encountered almost no resistance.
I’ve only paddled it in swells once, which ironically were not on the ocean but were a rare product of several unusually large motorboats on the local reservoir. Big, green, smooth rollers that would shoot the kayak down the fronts. I had a blast. There was no hobbyhorsing in those, but I did have to throw in some stern rudders to keep it going straight.
I did not mean to imply that the Squall is not seaworthy. It is very forgiving despite the hobbyhorsing.