Hiya folks, I’m wondering if somebody can tell me if there are typically a distinct feeling between a kayak’s initial stability and it’s secondary stability, what should I be looking for when test paddling a kayak in a lake or so? I know from being a cyclist who bike commutes on semi-slicks (smooth center tread for light rolling resistance on roads or hardpack dirt, with treads on the side for cornering tracking) that there is a definite edge on many semi-slicks between when you are cornering hard and fast and leaning the bike, but then you corner enough so that the tread hits the dirt. There is a definite period in between where you are cornering but not yet on the threads on some semi-slicks that you have to get used to and know about, especially if you’re used to a full treaded MTB tire. Does this exist on kayaks, dependent on the hull chime or profile?
Jay
Stability is expressed as a curve…
...for a reason. The forces involved vary with the lean angle and the shape of the hull. A boat can be very progressive with a slow roll over once past the capsize point, or is can be very stiff with a sudden snap to being inverted once you're past the edge. I've been in boats where there is virtually no difference in righting force between upright and laying on it's side (common in racing boats).
There is a good article on stability on the Guillemot web site. You can see it at:
http://www.guillemot-kayaks.com/Design/StabilityArticle.html
A Cyclist’s Observation
I’d say that this also varies greatly from boat to boat. To some degree this may be dependent on design (soft vs. hard chine, etc.), but even here, there seem to be no hard, fast rules. On cycling tires, the design profile itself is mostly responsible for this-more rounded profiles tend to have less resistance from transition to transition (think soft chine), while a hard-edged off road style tire with pronounced side knobs for extra ‘bite’ when heeled over, may snap over faster past the knobs (think hard chine). The knobs themselves may flex also (why you rarely see tall knobby tires used for hardpack conditions, they squirm and then give with little warning). Tire manufacturers also play with different compounds and even TPI(thread) counts, giving each tire a different cornering feel. On one road motorcycle I recently purchased, the prior owner had commuted largely on the highway. Consequently, the tires were worn flat down the center sections, with a pronounced ridge to either side. This made for a very insecure feeling when cornering, as the bike would literally ‘fall in’ to the corner when leaned. Once on its sidewall, it stuck quite well, it was the getting there that was unnerving. (Water is far more forgiving than pavement…) Kayak-wise, I owned an Eclipse which transitioned with little effort, but also little feedback-I think I may have defined it as a fine line between on edge and in the water-like playing the trombone; where you are is largely a means of memorizing the position. Paddling an NF Legend conversely, felt to me like it has a very definite feeling on edge-almost indexed, but quite low, almost nervous, on initial stability until you get it there, then wham, you can hang out all day. I liked that feeling though-it always felt ‘ready.’ My Explorer is a nice mixture between the two; very positive and provides tons of feedback along the way. It’s very user friendly. As a cyclist used to feeling tire slip angles, etc., I wouldn’t be surprised if you’re able to feel more subtle differences in the way different boats edge, particularly as skills increase, and be able to quantify them as well.
Also no “audio” indication
as when my knobby sides start hitting the asphalt in a decent lean. More like the feeling of traction and no noise when you lean in the dirt. If you know bracing technique then you may not get wet but it’s kinda fun (in the summer!) to go ahead and roll over as you learn where secondary begins and ends. Like was said earlier though, some hull types are very subtle. My hard chined Chessie 17 lets you know when your on the secondary by the distinct feel. Some boats I have tried do not “feel” right since I am so used to the one hull type.
Audible warnings…
…as opposed to the audible warning on a bike when you hit the pavement… 
I’ve read something on the web trying to state that a bike has no initial stability… I dunno, I’ve seen what some of these trials riders can do! I’m OK at a standing track stand on my mountain bike for a short bit but can’t really do a seated one yet. Easier to get some backwards pressure when standing for me.
Anyway, thanks for the reply.
Chine
So, for a kayak designer that is not making a racing boat, but wants to be fairly sporty without being a racing hull, there’s a balance I presume between a soft and hard chine and probably many flavors in between. I am looking at a bunch of “performance” orientated touring kayaks, one of them being the Impex Mystic which is described by Impex as being a Medium Chine, and a Eddyline Merlin LT whos website doesn’t say anything about the hull shape other than says it has high initial and secondary stability.
I’m also looking at a bunch of others, but want to know what to look for when I go on a test paddle.
Jay
visual cues
in kayaks.If you are viewing fish upside down you have passed the secondary stability point. Just kidding, best to try em and see what siuts your needs best. Seems to be many variations inthe diffrent boats I tested.
I too have had many questions about…
…kayaks and their primary and secondary
stability but not as many as my wife has had
about mine.
Eddyline Merlin
Eddyline Merlin has a shallow vee and rounded chine.
Thistleback
Neither of those boats…
...is a "performance" kayak, though they are good quality boats. The Merlin is essentially a high-end recreational boat. The Mystic is a good sea kayak for smaller paddlers or a good ocean play boat for medium to large paddlers.
As for chine shape, don't fall into the trap of attributing too much to it. A boat can be built with any chine shape and have the same overall handling qualities. Hull design is far too complex for any single element to define a design's characteristics. Your best bet is to ignore the chine shape and any marketing hype and paddle the boats in question. If that's not possible, ask if anyone has paddled the boats you're interested in and see if they can provide you with a comparison.
A bicycle has no initial stability
If you stand one up and let it go, it falls over. On the other hand, if you put a kayak on the water, it stays upright. All the stability of a bicycle is active, being provided by the rider. A kayak has passive stability that can be augmented by active stability provided by the paddler.
Chine Shape
doesn't say anything although a cut-away look of the entire gunwale down to chine to keel shape will tell more. The boxier the shape, the more primary stability over secondary. The more "V" shape, the more secondary over primary.
Most beginners find primary stability comforting. The ability to sit still in flat water and not feel wobbly. But that stableness works against you in waves because the hull bottom wants to stick to the wave surface which is angled (and thus unstable). Secondary stability won't feel stable in flat water because it wants to lean on one side or the other of the keel. However, will shine when in rougher conditions, especially beam to the waves, because the keel will want to stay vertical (provided nice, loose, relaxed hips of the paddler). You may want to refer to this page at One Ocean Kayaks. It gives written overview of some disign factors but also illustrative graphics.
http://www.oneoceankayaks.com/kayakpick.htm
As far as the Mystic is concerned. I think it favors more primary over secondary stability. Still, it's a "forgiving" boat in that the rounded chines don't catch as easily in weird waves and currents as a harder chine boat would of similar cut out profile. I find it an easy boat to scull and roll and even to edge and lean a bit. It takes time to develop those skills. I have not sat in the Merlin and can't comment.
sing
You’re like those inflatable punching
clowns. Just enough initial stability to stand up for the next blow, but unbeatable final stability for a quick return.
“Weebles wobble…
…but they don’t fall down”. Just ask Derek Hutchinson. 