hello im new to hopefully getting a kayak,in the past ive owned a cheap bath tub canoe now discontinued from meijers dept store years question is i understand the that initial stability means a good stable boat in flat water. but im confused as to how secondary stability can be more stable in awater that is rough,choppy,ect. how can that be more stable in rough water when they are not stabe in flat water. if you feel like your gonna tip on a smooth lake how can you feel more comfortable in rough water?

imagine a flat-bottomed raft
Tom Sawyer style.

That would be good and horizontal in flat water, but on a big wave it would be diagonal–conforming to the “side” of the wave. Not much fun to be on.

Now imagine a water-logged telephone poll in the water. On flat water its rolly. But on a wave the it just goes up and down, over the wave. If you could somehow hollow it out and ride it out inside the log, you’d find it may be less prone to dramatic tilts than the flat raft.

Kayaks with good secondary allow you to ride it out on the face of a wave and still stay upright. Or they allow you to get your boat way over on its side and still feel like you have plenty of support. Something like that. Hope that helps.

One way of seeing it
Try thinking of it this way:

A boat with a lot of initial stability likes to keep it’s bottom parallel to the surface of the water all the time. So, if the water starts being something other than flat, the boat is going to want to go with the surface of the water, and pitch with the waves.

A boat with less initial stability doesn’t care so much about the surface. It’s kept upright by the balance of the paddler as much as by anything else, so waves don’t affect it as much. If the paddler keeps their orientation and balance with the horizon, so will the boat. At least a bit easier than the flat-bottomed boat would. The bigger and steeper the waves, the more you notice it.

Secondary stability is the boat’s tendency to capsize once leaned just so far. The farther you can lean without it going over, all other things equal, the more secondary it has.

kinda like…
On smooth pavement, a car is going to feel most stable with a fairly stiff suspension. But for serious off-roading, you want a long-travel, fairly soft suspension – the kind of thing that’d feel unstable on smooth pavement.

Another example:

Look at photo C. A boat that was too stable wouldn’t let you lean into the wave. You’d probably end up leaning away from the wave on the wave face, and quickly capsize.

There’s nothing wrong with wide, stable boats for some kinds of paddling. But as your skills develop, you may find that you want a boat that’ll lean when you want it to. Being able to easily put a boat on edge when you want to often makes it easier to control.

it’s not more stable

– Last Updated: Jan-07-08 1:17 PM EST –

That description gets tossed around a lot even at kayak/canoe shops and it's WRONG.

The problem is that it's an apples and oranges comparison between a static measurment of stability and a persons INTERPRETATION of a dynamic response on the water.

You could get a scale and a lever to measure primary stabililty, "Xlbs force at Y degrees lean) to measure "secondary stability" you'd have to make a chart and describe a curve,,but it wouldnt be describing STABILITY or resistance to capsize. Two TOTALLY different characteristics.

It's like comparing algebra and calculus. Related but not the same.

If you're in a flat bottomed kayak thats 24" wide it's more stable than a round bottomed 24" wide kayak,,in flat water or rough water.

The difference is that the round bottomed kayak can be controlled more easily because it IS less stable. Therefore the PERCEPTION is that it's more stable in rough water because it's not being tossed around as violently as the flat bottomed kayak AS LONG AS the PADDLER is flexible and CONTROLLING the kayak.
The person who might capsize in the flat bottomed kayak WILL capsize in the tippier kayak IF they do not control their position in the kayak.

The flat bottomed kayak will resist capsize more strongly than the round bottomed boat but at the capsize angle BOOM, it's over.

Ok, the round bottomed kayak of the same beam will go over to the capsize angle more easily but the PADDLER can bring it back up more easily. It's the fact the round bottomed kayak IS tippier that enables one to hold ones torso over the center more easily and stay upright in waves that makes it more comfortable. The tippy kayak enables the paddler to transmit boat controll more effectively.

The problem most often is that people confuse a skinny tippy boat that is good for a light person as applicable for a taller heavier person..."but it's got good secondary!!"

Throw out the idea that a tippy boat is good. That's like saying a light bicycle is good, a car with a lot of horsepower is good.

A boat that is responsive to your skills is good. Whether that's a hull shape thats 23" wide with a round bottom or 22" wide with a flat bottom is unknown until you get in it.

The whole idea of "good secondary" doesnt take into account differences of cg or skill level. Or actually the term secondary REQUIRES a person to interpret a dynamic characteristic. Put a brick on the edge of a canoe and you're measuring stability. So the trick is to get into the kayak yourself and determine what it means to you. If you cannot interpret the experience its pretty much moot.

Second hand interpretations of boat handling are very limited pieces of information. About as useful as linear dimensions,,but its something so it gets used.

Y’r right
Like I said, it feels more secure. But that’s an acquired feel.

The thing is that so many people seem to acquire a similar feeling of what is secure in waves over time in boats…

words get tossed around
I’d much rather have a wider round bottomed kayak than a skinny round bottomed kayak if I don’t need the long skinny kayak. The wider round bottomed kayak has more primary stability and is more controllable on a lean near the capsize angle than the skinny tippy boat.

The idea that we are all going towards the tippiest boat for the greatest control at the capsize angle (secondary) is flawed reasoning. If that was the case we’d be paddling logs,or racing kayaks.

Another little talked about angle:
Materials. Those of us who paddle folding kayaks and inflatables have an advantage in stabilty. Folding and inflatable kayaks (like traditional kayaks) flex some with the wave and don’t get pushed over as much.

Some folding kayaks can be just as tippy though because they are narrow.

Whitewater slalom boats are designed
to be edged easily by the paddler, with good secondary stability, but surprisingly, most of them feel quite “firm” in the center position. They are narrow, especially the kayaks, but because of the design of the chines and the sides, they are, for their width, VERY disinclined to roll over, while inviting the paddler to assume any needed lean and giving force feedback proportionate to that lean.

The best “new school” kayaks also do this, and some canoes do also. I have experience with only one touring kayak, my Necky Looksha, and it also has an excellent resistance-to-edging force curve.

Now with illustration

Also a good read:

Need I think is it
So often these posts come in from new paddlers painfully short of info about where they are likely to end up paddling. When I see a thread like this one, I tend to think it is someone who got into a rec boat for puddling around and is now contemplating bigger water and seeing many people in longer skinnier boats. So - maybe I am way off base there.

Also, the flat wide idea only works as long as you can still control it. The cockpits that go with many of those make that pretty darned impossible for an average sized female, at least without some major retrofitting.

OneOcean Kayaks is great

– Last Updated: Jan-07-08 3:50 PM EST –

he's helped provide a lot of good information for builders in clear format. The epoxy test is good.

Seems to me the term "secondary stability" is a misnomer that would be better described as "responsive near the angle of capsize"

Yeah, “primary” and “secondary” are not the clearest terms at first.

I sort of like substituting (at least mentally) the terms “static” and “dynamic” stability instead. These to me are more descriptive along the lines of the functional on-water use differences the others are describing - and the OneOcean site illustrates. These also imply that stability in kayaks involves a paddler/kayak system in varying conditions, not just a hull and related numbers/values.

But I don’t get to make up/change already standard terminology - so I just translate it for my own needs.

So, I have an old Noah composite
kayak that is “responsive near the point of capsize” but has no useful secondary stability. So I don’t think your alternative terminology is going to work.

What we all mean by secondary stability is that the boat firms up to a supportive degree as the hull is heeled over. That’s the kind of responsiveness we expect.

thanks everybody for all the info and helping me understand a litle better.i think come tax time im going to go for a touring kayak the first time a round.i dont have the extra space for extra yaks as i learn the ropes,nor have the xtra money to upgrade as i learn either. i figure when the weather turns nice ill have plenty of time to learn from mistakes and hopefully have enough time in the seat to be ready for next up coming hunting seasons.i want a touring yak to be able to carry a lot of my gear and camping supplies and be able to handle a big resivours wind and chopy waters in the fall and wintertime weather conditions.thanks again


for me
secondary means I can control the kayak with my hips comfortably through a range of motion. Having some support is a part of it but not support that sets me on some firm edge like another flat bottomed hull.

I guess the question is to what degree do you find that support? A wide v-bottom boat wouldn’t have much desire to sit flat but would flop over and be very stable but a wide rounded bottom would enable me to play with the edge better.

ha ha ha
you say that now, but you’ll be back for more boats

they always come back

Excuse me??
Stability has less to do with width than with hull design. My P&H Sirius has a 20.5" beam and is the most stable boat I’ve ever paddled. I can literally set it on edge on the ground and it will stay there.

my impression as well
it was real stable leaning left,or right

That’s one reason I don’t like markedly
V-bottomed boats. They’re fishy at rest, and firm up when tipped in a way that does not make for control in edging.

I believe that a generous amount of predictably increasing support is important if one is going to have much control when on edge. All the kayaks and canoes I know of that have a reputation for good handling provide good increasing resistance when leaned. There may be exceptions, but I haven’t seen them in whitewater.