Demystifying Stability ???????

-- Last Updated: May-05-09 9:22 AM EST --

I would be really interested in fellow paddlers thoughts about the role degree of stability plays in

1. choice of boat for certain uses

2. skill development

3. forward speed, turning, rolling, bracing effectiveness, tracking

4. safety

It seems there is some fair amount of mystery and myth surrounding this topic that confuses me about how to think about whether stability matters all that much or whether we might pay different attention to this factor in advising novices and intermediate paddlers regarding boat choice and skill development, how the boat will perform, and safety issues.

In reviewing past posts on this topic there is a fair amount of heat and somewhat less light shed on this topic. It is kind of like when you get 100 dog trainers together, none of them agree on anything (not my view, what trainers say about each other often)
So to facilitate a discussion of this it might help to talk about stability as defined by

1. Initial or primary stability is the amount of heeling force from zero to 15 degrees of lean.

2. Secondary stability is the amount of heeling force from 15 degrees to approximately 35 degrees of lean

3. Linearity is how flat or even is the heeling force from initial to capsize. (Does it go from almost nothing to maximum to zero sharply or slowly and what is the rate of change in this force)

So OK, what do you all think about this mythological concept??? Does it matter all that much? Does a boat with little or no heeling force help or hinder skill development? Are there differences in safety in a boat with high secondary vs one with virtually zero? What about boats with high initial and little secondary, or little initial but high seocndary?

Are boats "easier" to roll that have low secondary, and if so, is this a good thing or not?

Must a boat have a really round hull to have a higher top speed and be more efficient? Are boats that have more secondary necessarily harder to turn or surf less well or better?

Are there significant safety issues regarding boats with little or no secondary and very narrow widths in prolonged conditions, or are boats with higher secondary giving the paddler a false security?

And so on!!!!

my 2 cents
I don’t like boats with very high initial stability and very low secondary stability even for beginners. These boats tend to go over quickly when they start to go and the high resistance to heeling the boat inhibits utilizing boat lean to facilitate turns, or block water entry in open boats.

As far as rolling is concerned, I have found that I am not very good at predicting how well a boat will roll from looking at the hull design. In a canoe, one can get a sense of how easily it can be rolled by dipping a gunnel to get some water in it, and seeing how easy or hard it is to heel it from side to side. I have not necessarily found boats with high secondary stability easier or harder to roll than those without.

I think the effect of hull shape on wetted surface area and thus maximum speed matters only for those competing at a very high level. True round bottomed boats (as opposed to shallow arch hulls) are so inherently unstable as to be useless for anything other than going fast. Imagine sitting on top of a beachball and trying to paddle it through the water.

I once had a creek kayak with a quite rounded bottom (it was not a true round bottom but closer to it than any other boat I have had). It was quite easy to roll, but unstable enough that I quickly got rid of it. It would have been great for a rolling competition though.

another thought
Some boats with near right angle chines can be leaned right over onto their sides and maintained in that position with a scull, then brought back upright with a brace, hipsnap and head dink.

In this case, the degree of lean from vertical may be 80 degrees or more. I’m not sure if this trait is properly called high secondary stability since the boat has “tipped over” in the sense that it requires at least a brace to bring it back upright.

boats “easier” to roll
Many people believe that boats with high secondary stability are harder to roll. I would argue that they are not harder to roll but do require an adjustment in technique. The default procedure for most people is to expend a lot of effort at the beginning of a roll and much less near the end. For a boat with high secondary stability the timing of reaching secondary stability resistance and dropping off effort coincide and the roll fails. All you need to do in that situation is delay maximum effort. You can delay effort using breathing. Exhale lightly as you hip snap and when you get to the effort point exhale sharply. I say “woof”. That extra burst of effort will get you past the secondary stability point.

I may have to try that in some open boats that I am just missing my roll in.

very cool
good idea, I say! It shows both the adjustment and the benefit of that type of boat. cool.

For me:
When I first started kayaking my main concern was stability with the new little rec boat I bought.

When I bought my second kayak, (a sea kayak) my main concern was once again stability.

When I bought my third kayak, I had two main concerns. Stability and speed.

I have toyed with the idea of getting a ski, but not done it since it would only get used in races, but if I did get one my main concern would be speed, since they don’t have much stability any way.

I don’t ever even think of rolling, since I am not interested in it, so that never comes into play with me.



skill development

– Last Updated: May-05-09 4:50 PM EST –

When I first picked up my P&H Sirius, I had gotten to demo it in a pond. Then I took it into the harbour and the lively feeling of it combined with stability characteristics had me tensing up. I had to keep paddling forward to keep a comfortable level of stability, and still felt quite nervous. If you're not familiar, you don't feel that heeling force which would allow you to be somewhat off balance while on edge.
There was enough information out there on the Sirius that I was convinced I wasn't just paddling a crappy boat. So it was either reserve it for fair weather flatwater, or practice and learn what it takes to get comfortable in it.
I learned more in that boat, because it has to be well edged to turn, and it doesn't have that secondary spot kind of holding me up, than I ever have from any other boat. The main thing it taught me was balance and paddle blade angle control. Always keeping your weight centered in the kayak, and knowing how to handle your blade when you want to go beyond centered. Once I learned that, secondary stability in other kayaks was no longer a crutch. Before I learned that, it was for me. I'd edge my kayak and try to get right to that point of strongest resistance, and if I went beyond, I'd have to roll back up. But I figured it to where that rarely would happen. After the Sirius, if I'd go beyond that point, my paddle would just show up at the right angle and put me back to where I needed to be.

So I learned in a low stability boat? Still, why would I want that? I don't figure that this necessarily translates to all kayaks with such stability characteristics, as there is much design at play here, but when I feel that twitchy feeling in little wavelets, I extrapolate that this behavior will increase in direct correlation to bigger wavelets, and chop, and waves. It doesn't. I expect to feel a strong force from the hull wanting to lean one way or the other on waves, and I feel much less than expected. I expect to be slapped around a bit, and waves wash by without my having to react.
I hear people say that it's the paddler, not the kayak, in reference to many things. That's probably most often the case. I prefer a straight tracker to teach myself to turn, a squirrelly kayak to teach myself direction control, an unstable kayak to learn edge control, etc. Then I can hope to make decisions based upon the kayak's capabilities instead of my own skill limitations. Of course, these things are personal choices. Do what works for you.

Can you give examples of boats that
have high initial stability but low secondary stability? We often criticize such boats, with drawings of flat-bottomed canoes being thrown over, but I think most Grummans, for example, are not deficient in secondary stability. I would expect your nominations to come from kayak ranks.

My '82 Noah Magma is like that.
Broad flatness in the bottom, and the chine angle is about 100 degrees— the sides cant inward. The kayak has weak initial and secondary stability, and can be leaned up on edge as long as one has a brace ready.

I bought this boat from the designer, Vladimir Vanha, and I used to inspect his Magma for the SE slalom races. Once I had it outfitted, I was at first mystified that it did NOT have the stability typical of many modern “new school” kayaks. But after getting used to it, and thinking about Vanha’s own paddling history, I realized that all of his early ww kayaks were rather round, like everyone else’s in the 70s and early 80s. He designed the Magma with a semi-planing bottom and hard-biting chines, but he KEPT the low initial and secondary stability expected in kayaks of the time. He expected to use dynamic lean control to make full use of the bottom and chines rather than “sitting” on a stable raft that had to be forced into leans.

He abandoned this approach for the Jeti and Aeroquatic, which shows that it did not make a user friendly boat.

…on the use and the paddler.

I demo’d a few standard boats in calm water, up to as tippy as a Greenlander and Silhouette. I was interested in sport/fitness, so was eyeing a tippier, faster boat. I felt comfortable in all boats I had tried and wanted to demo a Rapier 18. At the demo, the dealer rep told me he would GUARENTEE that I would go over in it, and that they didn’t even bring the Rapier 20 to demos cause it was too tippy. So I didn’t try the 18, even though I was comfortable in all boats I had tried prior to that.

Ended up buying a used catalog Rapier 18 un-demo’d, paddled it for about 4 hours with no problems, and then bought it’s twin, a catalog Rapier 20. I paddled the 20 all last summer as the 18 sat in dry dock after it’s 4 hour initial use. I have never gone over in either boat, but I have had the luxury of learning the boats on a relatively small and calm inland lake. I think by doing this I have enhanced my skills quite a bit. I have read a lot and had a fellow paddler show me a wet exit so I was not all that fearful of capsize. I have worked my way up to 2-3 foot wind driven waves and wake-board boat wakes from the side (abeam?) in both boats. Learned to roll in the 20 on the third try. I am now confident, after one summer, to at least take the 18 out on large inland lakes and face the “unknown”. Hopefully with a fellow paddler/companion.

In my experience, the 18 and 20 have similar primary; they are tippy even when you turn around to look at the rudder, and it has to be done cautiously until you get used to them. The 18 seems to have more secondary in as far as once you go past the 15 degrees primary it still feels like there is a little secondary “catch” so as to give you a little time to react. With the 20, it feels like once you get past the 15 degrees of primary, you get just enough secondary catch to give you the most subtle hint that you are THERE! and if you don’t react quickly and catch yourself, you’re goin’ over! Kinda like the difference between a saucer and a log! Both have very round bottoms; the 18 has little chines behind the seat, the 20 appears maybe little flatter between the chines in the mid section.

I love both boats; the 18 not quite as fast and more manageable in conditions, and the 20 definately faster but takes a bit more muscle, patience, and nerve to turn about and control in conditions. I think both have the potential to handle, to a point, more rigorous conditions. It will just depend on my skill and confidence level.

I would certianly like an “unknown conditions” boat like a Romany or Nordlow to take on paddles where the conditions might be more unpredictable, like Lake Superior or other big or rough waters. But I am glad I bought and stuck with these boats. I think I would be bored with something like a Silhouette or Greenlander with the way I paddle…but again, would certianly enjoy one for conditions or longer expeditions in what might be rougher water. I take the 20 out when the water gets warmer when I get bored with the 18 and wanna really PUSH, but it is in a way too much boat for a little 80 acre lake!

My 2 cents and some change!

Engagement: Risk Homeostasis
Maybe the most fun comes from finding your “risk homeostasis” point???

Maybe that is why we deliberately choose a boat that requires us to feel our balance, and dynamically paddle, rather than be mindless. Or to take a boat with more stability into rougher stuff to get to that same place.

When I got back into kayaking I got a used Andromeda, and realized all I had to do to capsize it was to look around for another paddler. This boat required that I quickly relearn all my skills. And I actually developed my current dynamic paddling skills approach, something I really did not have as a younger paddler.

Sports psychologists studying why athletes take risks and the amount of risk they take have found that too little risk does not engage us, too much overwhelms us. There is a homeostasis zone of just enough but not too much. This changes over time. On the plus side this is that amazing human capacity to grow and learn. The negative is that we place ourselves into more and more risk to achieve this, called risk creep.

But maybe the biggest advantage in a boat like the Nordlow is that we develop our skills and have a better appreciation for what will happen in a storm setting everyday. Like WilsoJ says, he won’t bring it surfing. He and I have learned by these boats what our abilities and limits are and how better to develop.

And beyond the boat, I realized as an older paddler that the young guy muscled everything. Now I have learned that each stroke is a dynamic balance point moving on to the next balance point, kind of like hopping from one boulder the next crossing a raging mountain river.

It is an exciting and growing way to paddle I find.

Stability demystified
I have a simplified definition of stability.

I consider a boat “stable” if I have not (yet) fallen out of it.

Once I have fallen out of it, the boat is considered to be “unstable”.

good questions
I think a lot depends on the experience of the person paddling and the range of hull designs they can handle in a wide variety of conditions.

A more experienced kayaker is going to make their choice based on how much of one feature they are willing to gain in another, but they can handle a wide range of kayaks well, and are going to be able to assess the kayak on their own.

Which isn’t to say that a less experienced kayaker doesn’t know what they want or expect from their kayak and what they want to do with it. (go out, have fun, be safe)

I find having the exact fit and size makes a huge difference with how well a more challenging kayak handles on edge. I had to install foam on the bulkhead of my Nord LV and even then had to trim it within a quarter of an inch. I have just enough foot room and any less it would be impossible to be comfortable on edge. The deck hight also has to be ideal for me and any more or less would have a major impact on how well it edged, turned, etc.

I find these are more common deal breakers with people, (especially people with big feet) rather than obsessing on stability charts, and deciding which kayak is safe or not for an intermediate or advanced kayaker.

One kayak might have better edging, and another might be more efficient to paddle, yet both be very capable kayaks in the right hands.

I find it a very difficult decision to strike the perfect balance, but glad there are so many excellent kayaks to choose.

My thoughts…for what it’s worth
Like wilso you have a fascination with boat design and a curiosity about why hulls perform the way they do. I think that’s awesome! I’d recommend for you guys to try and chat directly with designers. If ever on the West coast I can make introductions. It’s a fascinating process designing a kayak.

You blend the science with experience in paddling and you refine, refine, refine. The fun is when you shape a hull to do something, applying all that your design team has collectively learned, and …nail it!

Another fascinating thing about all of it is the various tweaks and their real world impact. I know that many of the sea touring kayaks of some fame had little formal science driving the designs, rather tradition and just plain old paddler / designer know how based on water time. It is science in another context and very valid.

Today’s blending of computer and experienced designer allows for some really amazing things to happen quickly.

I think it would be fun for guys like yourselves to buy some foam and take a stab at shaping your ideas and seeing how they work. I think you’d love the process and so much about all of this would become second nature.

We never stop learning eh?

We never stop learning eh?

– Last Updated: May-06-09 12:50 PM EST –

"...he not busy being born is busy dying." Robert Zimmerman

Stability Confusion = Beginner Paddler
If someone is confused about the relationship between primary, secondary stability, ease of rolling etc they have not spend enough time on the water.

When we start talking about risk homeostasis and positional equilibrium hysteresis it’s time to shut up and go paddling.

Isn’t that always the way
As soon as you get a good, truely arcane discussion going, some sensible person shows up and throws cold water on it.

it’s not mystifying
people mix apples and oranges.

“secondary stability” is a misnomer as it mixes a static measurment with a dynamic characteristic.

primary stability simply describes how much a kayak tilts for a given force acting on a lever, responsiveness near the angle of capsize is a better description than “secondary stability” as there is no stability at all without a bracing paddle stroke.

Lee say more
Lee say some more about secondary. Boats vary considerably with both how much heellinf force there is past say 30 degrees and how much it decreases and how fast.

Is that what you mean by responsiveness?

I remember reading about the recent race around N. Z. And how the teams in Brit boats were beaten by wider boats with secondary larger.