primary stability and tipping

Okay, is my understanding correct? While less primary stability may feel tippy, it is the secondary stability that is actually related to tipping over. Thought of this way: a boat with a sack of potatoes in it may wiggle around a lot in choppy conditions if it has low prmary stability, but it is the secondary stability that will cause the boat to go over or not?? (I guess if you are not a sack of potatoes, and low initial stability makes you nervous, the nervousness might make you do something that pushes the boat beyond what its secondary stability can handle – but that’s an indirect effect of primary stability on tipping.) Right? Wrong?

Actually, primary and secondary
stability kind of shade into one another. We started with a canoe that had a very arched bottom and didn’t feel firm near center position. But when tipped, it firmed up quickly. Now, in our old age, we have a canoe with a much shallower arch that feels nice and firm near center. It takes a good bit of force to lean it, but from its shape I know there will be a sudden tipping point out there.

The better canoe builders will not market canoes for the general public that go over too easily. But sometimes, for customers that want it, they provide a rounder bottom for speed, and those canoes will not feel as firm around center.

It’s really loose hips that prevent capsize. You learn to keep your body mass properly over the canoe’s footprint.

You learn…
G2D is spot on: “You learn to keep your body mass properly over the canoe’s footprint”.

Some folk seem to have an issue with watersports involving… water, but to my mind this shouldn’t be a big deal - paddlers generally don’t disolve on impact with it… with the ignominy hurting more than the immersion!

Two minor points:

  1. Pretty much ALL mainstream hulls are stable enough for general paddling;

  2. Most dumb dunkings would happen in pretty much any hull :slight_smile:

    Seriously, standing up, fishing, stopping to take photos with a fancy (non waterproof) camera and so on might raise issues… but staying upright whilst paddling from A to B on flat water in anything less than a racing hull is not overly complicated!

Boats don’t tip
People tip them !

Jack L

yup you are mostly correct. esp when a person is a newbie a boat that feels tippy (1st stability) can make a person over react in a panic and tip the boat over.

My 1st boat I called my boat of a hundred heart attacks"

It always felt tippy to me esp. when just hanging out doing wildlife observations etc.

Now all these years later it always seems rock solid…the boat didn’t change, I just got used to the “feel” of it.

but I don’t give it out to friends who might be joining me for their 1st time paddling. I let them use a more stable feeling boat so they don’t tip over in it.

That way they can enjoy the outing and not be stressed out unnecessarily, when all they want to do is relax and have a good time.

I think I had it easier in canoes
because my previous human powered water craft was a 27 foot long, one foot wide, single scull, which had no primary or secondary stability whatsoever. The sculls (oars) provided the stability. So canoes at first seemed like aircraft carriers by comparison.

Degrees of heel…
Much the same as sailboat hulls really. At a certain point in the boat being heeled over, measured in degrees, a kayak with noticeable amounts of what is usually called secondary stability will actually harden up and resist going past that point. Up to that point, the boat’s own tendency will be to return to an upright position. A tense or nervous paddler can find a way to get it past that point by not staying centered over the boat, leaning out and thus taking the boat over.

A boat with a high degree of this factor will usually have very little resistance to wiggling around within degrees of heel that are less than that particular point. How that feels is often called primary stability - the more easily a boat moves around thru lower degrees of heel, the less primary stability gets ascribed to it.

No one has, as far as I know, designed a hull that’ll resist wiggling around in lower degrees of heel to the same amount it’ll resist going over at higher degrees of heel. You have to opt for more resistance in one area or the other. So rec boats resist wiggling around in pretty upright positions because that’s the water they’ll be paddled in - flat. Sea kayaks have more resistance to capsize over on their sides, because that’s the position the boat will be moving thru in the process of sliding around on waves.

Sea Kayaker magazine has charts of this stuff in boats they review - might be worth a look.

Is there typically a tradeoff
between primary and secondary stability, that is, high in one goes with low in another (or maybe you compromise and get medium in both)? And if that’s the case, is that because of the available hulll designs or is it a matter of physics? Thanks for the info by the way! (Oh yeah, it was mentioned that a racing scull is low on both, so I guess that’s possible!) Part of my ciriosity is wondering about the truth behind ad copy that may say high primary and secondary stability.

hey there
great questions, but don’t make it too complicated OP.

primary stability is the boat in the upright position.

secondary is the boat heeled, as explained by Celia.

yes there is a tradeoff - more primary stability is usually a flat, wide bottomed both (examples are typical recreational kayaks). they are super stable on flat water, but as waves increase they present more of a surface for the wave to act upon.

As others said, with experience the paddler gets to know the secondary of his/her boat, and what to do w. it.

Discount the marketing blurbs and test the boats yourself. We all have different bodies, different centers of gravity, and balance. What feels fine to one is very tippy to another. By all means read and research, but get out and try a bunch of boats - and, if you can, do so in the context of a lesson or two.

Learning the proper way to edge and lean, and how your body position affects boat trim, will teach you more about primary and secondary stability than anything learned secondhand.

Go forth and demo!

Kinda yes

– Last Updated: Aug-04-10 10:47 AM EST –

It really is a matter of degrees and the audience for the boat.

A rec boat, intended to be used in flat, calm water by manufacturers' statements, is primarily marketed to to people who want to avoid a swim at all costs. So their tolerance for low primary stability is pretty limited. And in the context of flat conditions, the same boat may have what feels like a high secondary stability as well because it isn't going to be getting popped all over the place by 3 ft or more waves. That is, assuming the paddler got a good check on the weather before launching... :-)

A kayak being marketed to someone who wants to go out into more open conditions is likely going into the hands of someone who has accepted the possibility of the unplanned capsize or is even starting down the path to a roll and really good bracing skills. Between the expectation of being in more challenging conditions and the higher likelihood of their recognizing the need to get good recovery skills, this market segment is willing to accept less primary stability than the rec boat market.

So the high or good primary stability that a rec boat paddler wants may be an unbearable bore to a more aggressive big water paddler, making it hard to sort out manufacturers' statements across different types of boats.

This is where the stability curves start mattering, like in Sea Kayaker, because it puts a number on what is otherwise a nearly impossible discussion if you just use words like low or high or whatever.

Basically, the more of one kind of stability you get, the more you risk sacrificing the other. For boats that list themselves as high in both (low in both seems easy to achieve), you have to consider the market segment that ad or description is talking to.

By the way, I haven't mentioned WW boats because that's a whole 'nother discussion. They are really tweaked these days and you could spend a very long thread just on that.

think of it this way
A boat with a wide flat bottom wants to remain sitting level, in flat water. When you get onto a wave or swell, that wide flat bottom is going to try to stay ‘level’ in relation to the wave face. A narrower boat with a rounded or V bottom will try to stay more truly level, and dig down into the wave face.

Which kayak capsizes first
If you put a typical rec boat, a typical transitional (let’s say 14’ 24" beam) and a typical sea kayak out in a bay empty (or with a sack of potatoes in the cockpit), which one capsizes first when the wind and waves kick up?

If I’m hearing right, in spite of (or even because of!) it’s higher initial stability, the rec boat dumps first because of the flatter bottom that presents so much mass to the waves (lower secondary stability – the trade off). If I’m getting this right, there is an irony in that the beginner who may want to avoid a swim at all costs (and who may resemble a sack of potatoes!) would actually be better off in the boat with less initial stability and more secondary stability.

Yeah, maybe my curiosity is getting to the point that I do need to get a grip on the stability cirves!

yeah I saw a graphic
of that (flat bottom staying “flat” to the vertical wave!) online somewhere that made it really clear!

Depends on the paddler

– Last Updated: Aug-04-10 12:25 PM EST –

You are thinking too much and getting a boat over on its side too little.

All of the boats are likely to stay upright for a decent bit of time if they are devoid of a paddler and have decent skirts on. W/o a skirt, the rec boat may (and I am just guessing) go first because the big cockpit will fill up with water and the water will destabilize the boat. Loose and uncentered weight whether potatoes or water will make a capsize more likely, regardless of hull design.

Once upside down, the skinnier sea kayak with a smaller cockpit may be more easily flipped back upright again by the wave action - the rec boat will probably stay upside down once it is there. This means the sea kayak is going to be easier to roll up again as well.

Transition boats are just that and it'll vary by boat.

But the trump card is a paddler with a decent brace, which will keep all of them up.

It’s hard to talk meaningfully about
stability if we are picturing a paddler sitting or kneeling who is relaxed and staring at buzzards circling in the sky, or who is new at paddling and has not developed any automatic head, body, and paddle reactions to what the boat is doing.

It is true that large flattish surfaces, chines, and slab sides do present a target for the mindless efforts of waves or crosscurrents. But removing flatness and edges does not necessarily make for security.

For example, a rather round boat will be more strongly grabbed by crosscurrents than one with some flatness and chines, if the paddler has developed the reactions to work with the boat. A flattish hull will ferry securely across strong currents from eddy to eddy, at surprisingly steep angles, while a roundish boat must be nursed across while pointing up into the current.

One of the most secure-feeling boats I have ever owned, at least until waves jump all over its flat rear topdeck, is my slalom c-1. It is only 26" wide (excluding the vestigial wings which meed width regulations), and I am as tall above the hips as anyone on this board, but with just a little help from my aged reflexes, this little boat is totally confidence inspiring. Much more so than several wider, rounder c-1s I have owned and paddled. And this is not a matter of “flat bottomed stability.” It derives from the way the sides are angled above the edges. It is not a flat bottom that imparts stability, it is what the hull does when it starts to tip.

I think what happens when folks new to canoes get in one that is roundish, is that the visual width of the boat tells their brain they should be able to move around easily, and then when the boat moves some, they feel it is “tippy.” But later, if they are kneeling, or sitting properly with legs out and knees braced on the sides, they become part of the boat. The boat and the paddlers move together. And then there is no longer a problem.

Seems to me…
…that you can have both high primary and secondary stability. But it comes with a third penalty - a much wider boat. Take the Wenonah Fisherman, for instance. Lots of primary, pretty good secondary, 39" wide. You could take that to extremes, but how would it paddle?. My example canoe gives up some forward performance for a glut of stability. I guess my point is that you could have the flat, wide bottom and soft chines with lots of flair, and get all kinds of stability. But could you paddle it? Probably, you’d just add a sail…

Being a fairly new paddler myself, it also seems to me that primary stability is something that you eventually learn some indifference to. I mean - none of my current boats are known for primary stability, but at least in a couple of them I just don’t even notice that it’s missing. I think that comes naturally, once you spent some time on the water. Even though I stand in my canoes all the time, I have no need or desire for canoes with flat bottoms. It’s no big deal - just like learning to ride a bicycle.

many factors to stability OP
there is “perceived” stability, e.g. the classic feeling of tippiness, which may be due to any of these: unease of new paddlers, improper boat fit, stressful waters, weariness, hypothermia, seasickness, etc. Add in body type, balance, center of gravity, degree of paddle skill, etc. Lots of factors.

Can’t quantify that for ya.

And yes, water in the boat, like a sack of potatoes, destabilizes the boat. So does a paddler who shifts his/her weight improperly. The general rule is “nose over navel” to keep our relatively heavy human heads from capsizing the rest of us.

As pointed out above by JackL, the boats do just fine. It’s we who upset the stability curve, either because we enjoy it (we brace, roll, and take the boat on a third degree edge often), or because we make a mistake, our gear is contributing to a less than desirable trim, or we are too big/too small for the boat.

Go out on the water, you’ll see all of this.

Then there is “designed” stability, a broad topic for person more design-savvy than me (or most of us, actually).

For where you are at, the short answer is yes, most seakayaks have more secondary and less primary stability than most “rec” or “transitional” kayaks. It is a tradeoff that competent seakayakers are more than happy to make,esp. in textured water.

Why are there exceptions, as g2d aptly pointed out?

Well, for starters, length and width are factors, but just couple of many -volume of boat, where the volume is, depth of cockpit, shape of hull bottom & sides, (many more options than just flat or round, or inbetween), waterline beam (which is different than beam) etc.

You really need to go out and try some kayaks and canoes, and take some lessons, to FULLY appreciate what everyone is typing. Your own body will give you far more useful feedback.

I felt like this
When I first tested a few different kayaks some felt more tippy than others that is for sure. Some was me not being in any type of kayak/boat for about 20 years so I did feel a touch uneasy.

Well I bought a SOT kayak and been out fishing with it at least 20 times or more and from the 1st time to now it is amazing how much better it feels for stability. Now I have no worries about tipping over.

Another thing I did to feel better is I actually put my kayak in my parents pool and sat on it normally and sideways with my feet in the water and would rock it to see how far it goes before it tips over. I found I have a long way to go to make it tip on normal usage and really should never have it happen but if so I’m prepared.

Thanks, everybody…
…for the time and effort to discuss this a bit.

(My raising this is in the context of paddling my new sea kayak – an Eddyline Fathom, and previously a “transitional” for a couple of years. Just went to the local shop and discussed getting some bracing lessons in their pool – the natural water around here never warms up much. From the two shops in town, the WS Tempest 170 (which I already tried and liked) is the only “performance” kayak to be tried – they mostly have their outfitter boats, such as the Necky Eskia (and Tsunami’s) which I did buy used and sold to someone else because – being 25" in the beam I suspect – it didn’t feel all that different from my transitional boat (and I’ve felt no need for a rudder). So, while my demoing possibilities are limited in terms of experiencing various “performance” hull designs and associated behavior on the water, I do have the pleasure of getting more and more familiar with my Fathom! – and gaining more confidence as I learn to brace (and rescue and maybe even roll).

Thanks again for the discussion.

Another option
Lowering your seat even 1/4 to 1/2 an inch can make a huge difference. I have replaced the fiberglass seats in my boats with the NDK or Valley foam seat. I just use some contact cement and glue it right to the hull. I few days ago Celia mention Ray Wirth the Water Walker guy in Maine. I had my first offical kayak lesson with Ray a few years ago. Ray had me rock the boat left and right gradually faster and faster heeling steeper and steeper. You get to trust your braces and you learn just how far you can edge your boat. As Ray told me “You have to put the butt time in your boat to be comfortable.” “Practice your boat boogie Woogie”

I hear you, it took me a while to not tighten up and be anxious on the water. This helped me allot good luck make it fun.