Initial Stability in a Sea Kayak

Why would I not want to purchase a kayak with the highest initial stability - and secondary stability for that matter - assuming same width/length?

Some basic stuff

– Last Updated: Nov-14-13 11:56 PM EST –

Here are three reasons.

1. Any boat this is highly stable is resistant to tipping. "Duh", right? Read on. Any boat that is resistant to tipping tends to stay aligned with the water's surface, which is great when the water is perfectly flat, but not when the surface of the water tips a whole lot, as on the edges of sizable waves. A very stable boat constantly "tries" so stay aligned with the tilting of the waves, so you get tossed back and forth violently in the process, to the extent that you might find your "stable" boat on the verge of tipping over an awful lot of the time because your center of gravity gets so catywumpus. A boat that "tips easily" rides much more smoothly in steep waves, because in tipping easily, it more easily remains upright as the water's surface tips beneath it.

2. A stable boat is a slow boat. One way to make a boat faster is to reduce the amount of wetted surface area that there is in proportion to water displaced. Take this to the extreme, and the part of the hull that's in the water, as viewed from one end, looks like half a circle. That hull shape has no stability at all, and you don't want that in a boat (though some specialized racing boat are pretty close to that shape). The boat at the opposite design extreme, the one with the most wetted surface area relative to water displaced, has a very flat bottom. Yes, that's stable, but all that unnecessary surface area causes extra friction as the boat moves through the water. Somewhere between those two extremes is a hull shape which moves through the water much easier than a flat-bottomed boat, but is a lot less tippy than a round-bottomed boat, and often includes the good secondary stability as described in #3 below. In fact, this is a perfect illustration of why no single hull design does everything, or even many things, well.

3. Others here will be more expert than I, but the geometry of the situation makes me think you can't have high initial stability AND high secondary stability in the same boat. Here's why. A flat-bottomed boat when tipped to the extreme ends up with one edge shoved deeper into the water and the other edge lifted right out of the water. The result is an effectively narrower hull (there is less hull width in the water after the boat is tipped than there is when it sits flat). Naturally, a boat that "gets narrower" as it leans to one side also becomes less stable. A boat with high secondary stability does the opposite. The width of the hull that is in the water actually becomes greater when the boat is tipped, so the farther you tip it, the more "tipping effort" is required to tip it even farther. So, going back to my first statement, I can't imagine a way to combine these two opposing geometrical features in a single hull.

Other Stuff:
All these basic ideas interact with each other. As one example, moderate to extreme leaning of the boat can be very handy for several reasons, including to aid maneuvering, or to keep from getting flipped when suddenly entering water with a substantially different cross-wise speed relative that which you've been paddling in so for (this happens in swift water when when entering an eddy or leaving an eddy), and especially since many boats that tip easily also "firm up" (with increased stability) when leaned, it will be a lot easier to take advantage of leaning the hull. Leaning a highly stable boat isn't nearly as easy to do, especially since, as pointed out above, it actually becomes a lot more precarious a perch for the paddler when this is done. I'm sure plenty of other examples could be made along such lines.

Oh! OH! All that I've said applies to hulls in general, but since I'm not a kayaker I didn't think of one really obvious thing. A boat that's super stable (wide, flat-bottomed) is hard to roll, and the ability to roll is what makes a kayak so incredibly "safe" for a skilled paddler when simply making your way to a nearby shore isn't an option. A skinny boat "tips easily", but is likely to be more stable when leaned AND can readily be rolled, so tipping over isn't anything to worry about anyway (and though off the subject, it's worth mentioning that learning to roll makes you a lot less likely to tip over in the first place because of the feel for "rotation control" that you acquire).

Predictable Resistance

– Last Updated: Nov-15-13 1:05 AM EST –

No one likes surprises, uh-oh moments, etc., etc.
A "rounded" bottom kayak will give the paddler a very
predictable feel when among the waves.
A big ol' flat bottom feels safe; until that exact moment
where expletives are uttered and you get dumped.

How a kayak "resists" movement is often described
as its primary/secondary stability.
Various shapes of the kayak hull can modify,
the amount of resistance, to the outside forces.

I would say initial stability is that secure feeling
you have upon first entering the kayak.
Secondary stability is that feeling for when
you're about to be dumped , whether it is a
violent capsize or a just a gentle sliding roll over.

It's always a highly individualized unique purchase.
The kayak you buy, needs to fit your criteria; not someone else's.

Love the quote below :
"What the rest of the world paddles is
only important to the rest of the world."

Is this a sponsoon troll?

Another analogy
It’s like riding a three wheel bike vs. a two wheel bike.

Probably not
I get the physics.

But like many trying to move from beginner to intermediate, I still like initial stability (for photos and just general comfort), while wanting that secondary stability in reserve for rougher water. Finding the right compromise, as you probably know, is idiosyncratic.

But the question makes sense to most beginners.

Is this guy a troll? Have no way of knowing.

Please don’t assume the worst, though.

What’s interesting is that there are boats out there that have been rated by those companies that rent to all levels of paddlers that can have a nice compromise - at least by their ratings. I’m looking for and at a couple of those myself.

What do you want to do with the kayak?

– Last Updated: Nov-15-13 9:16 AM EST –

Shooting photographs often means that it is better to sacrifice some secondary stability (such as it may exist - there are arguments about that). It makes shooting photos easier and face it - very few people are going to be taking close-ups of pelagic birds in a sudden squall and steep breaking 4 plus foot waves. At that point the hands will be on the paddle, not a camera.

But high initial stability can get in the way for more playful purposes, because it could increase the effort needed to get the boat onto its full edge. Rock gardening is one example.

There really is no answer to your question without considering the intended paddling environment.

Try a Reflection…
There are other ways of creating stability, there are always trade-offs. Sterlings Kayaks “Reflection” has very good initial stability and an extreme amount of very progresive and deep secondary stability yet also is one of the easiest rolling boats around. I believe much of this is accomplished through the rocker profile changing the “in water” volume as the boat is heeled over. I weigh about 155# and often put even smaller first timers in the Reflection and none have had any trouble edging the boat, I also know many in the 250# range that have the same experience in it. The Reflection is in fact almost too stable and prdictable in all conditions; such that if you don’t somewhat regularly paddle other boats your skills get a bit lazy. There is a trade-off for speed; while the Reflection has a decent cruising speed it won’t go much faster no matter the effort. No other sea kayak surfs like it though :>). All the best, tOM

You may be unstable yourself. So
go ahead, and buy the most stable kayak you can find. Or, find a used Hobie catamaran and take the mast off.

When you find that the other sea kayaks are leaving you in the “dust”, or are running rings around you, then find a sea kayak that performs.

I believe you will find
that the performace of a highly stable boat will be something you will outgrow quickly. Characteristics (wide hull, deep keel, etc.) which make a boat highly stable tend to make the boat slow - both in forward progress and in response to conditions.

A sheet of plywood has excellent initial stability, but as a paddling platform, it is the worst possible design. If you were to try to stand on it, it would tend to behave according to the pressure (and location) of your weight, it’s inherent degree of bouyancy, and whatever movement the water would provide. Even though it has high stabiliy, once you put weight on it, those characteristics change instantly and it will try to escape from the counter forces of your mass and it’s bouyancy and will become catastrophically unstable (it will attempt to move to the sides or flip at very slight provocation).

While this is an extreme (and unrealistic) scenario, stable boats also share some of these problems. They tend to wallow in the water and when the forces exceed the design, they tend to capsize VERY quickly and be slow to respond to paddling imput. What looks and feels stable initially may be extremely unstable when you add weight (such as for a trip) and the conditions change.

A kayak needs to behave more or less predictably, allowing the paddler to adjust and respond. Often, some of the less stable designs perform amazingly well when conditions become rougher and/or weight is added to the hull.

There was a documentary (it may have been a NOVA episode, but I can’t seem to find it at the moment) where a paddler who could barely keep a baidarka (with a bifurcated bow) upright when stationary. He rolled up a couple of times after launching due to the lack of initial stability. Once the the boat was on the water, the performance in swell and surf far exceeded expectations. The boat become more stable and responsive at speed and is probably a good example of the other extreme (ie. plyboard sheet).

Most of us don’t want a boat that tippy, but all of us probably want a boat that fast and responsive. Every hull in between the two states must be a compromise or there would be a need for a single hull design and everyone would use it.


Good example of what I meant
You say it is easy to edge, which of course could not be true if it were extremely wide and flat-bottomed. It’s an example of what you can do with a hull that falls between the two extremes I mentioned.

I believe you will find that replying to
the original poster often requires scrolling up to the top of the thread so as to click on the very first “reply” button.

If you click on the “reply” button at the bottom of the thread, you may seem to be replying to some crabby person who has just posted something quite unrelated to your thoughts.

Just sayin’.

Some good post here. With experience, most paddlers gladly give up some initial stability for really good secondary stability. That trade-off allows for greater speed and safety in rougher water. Some paddlers need to practice bracing to get their technique to the next level. Then the more advanced boats make more sense.

OK, but note that most of the ww kayak
community have gone over to flat-bottomed, sharp chined kayaks. Even creekers are trying to do it, though they try to find flattish creek boats where the edges are lifted enough not to catch rocks.

In whitewater, flat bottoms and sharpish chines are necessary for optimum control. Except for steep creeks, round bottomed kayaks like the old Dancer are invariably pigs.

Thanks for the Replies!
Thanks for all the wisdom in your responses (and for not assuming I was a troll).

I guess my original questions was borne out of a little frustration from my most recent open water paddle. I have experience paddling a couple less stable hulls (initial stability I guess) which I particularly enjoy for their speed and acceleration: an Epic 18X&V8 and a Current Designs Cypress. Both are soft chined and a little lower in initial stability. I am fine on flat water or heading into wind chop, but give me any more that 1 ft. wind chop on the beam and the wobbly feeling just messes with my mind. Bigger swell or wind waves and I really can’t avoid tensing up and feeling nervous/anxious.

In contrast, I have paddled an NDK Romany and Seda Ikkuma in the same or bigger conditions and I can just relax and let the boat do its job. I feel more in control, more comfortable bracing, etc. On a side note, I find both these boats easier for me to roll so that also helps calm nerves I guess. With these boats I feel like a much better kayaker.

Not sure if I just need psychotherapy, hypnosis, or what? Or should I just stick with stability and give up the speed aspect.

You’re Not Alone
A kayak buddy of mine has had a QCC 700 for years and he prefers to borrow one of my boats with a bit more initial stability.

Spend more time mixing it up with boats

– Last Updated: Nov-17-13 11:00 AM EST –

The NDK Romany is one of those boats that many people keep around because there are many times in your paddling where you want to be in a boat that you can forget about. We have two boats in the fleet (one is a Romany) that we keep because there are times where we want to paddle but want a boat that will do a little babysitting.

This is not something to be looked down on, especially as you get older. Getting on the water at all is more important than the macho factor of the paddle.

That said, if you don't learn to relax more you are preserving an unneeded risk in your own paddling. One and two foot chop is not the kind of thing that should alarm anyone who wants to do open water paddling. And tensing up will inevitably make you a swimmer at some point.

I suggest that you spend time with boats that challenge you a bit on initial stability and find a way to relax more. Perhaps you could focus on sculling, not rolling, so you are down and in the water but still not swimming. A roll is so fast, it might not be helping you much with your tension.

Can you find pool sessions over the winter, so that you can come out in spring with some headway on this?

A lot, real lot, of people like . . .
. . . stable boats. Thus the popularity of rec kayaks among newbies and intermediate kayakers and tandem canoes for solo wilderness tripping.

Many posters here are not within those groups, and have a preference for faster or higher performance boats.

Much of paddling is mental. It should be fun. Or at least peaceful. No one has fun or is at peace when constantly worried about a twitchy boat.

Stability is also a value when you want the craft to serve as a platform for some activity other than the act of paddling for the sake of paddling – such as fishing, hunting, photography or cuddling.

If you “outgrow” a stable hull, you can simply get rid of it for a tippier one. Cuddling in a boat doesn’t require marrying it for life.

I paddle tippy canoes, but that puts me in multiple minorities. I decided to be more majoritarian in this response.

that was great
Nice thumb in the eye of the volunteer forum cop.

ok, that was really good
I was just trying to think of a succinct and accurate answer. Yours is perfect.