I suppose the info I want has been on this message board a hundred times, but, since not too long ago I was given exactly opposite answers by two different kayak dealers, here goes anyway. Regarding soft versus multi chines on kayaks, how do the two different designs affect primary and secondary stability? Also, how pronounced is the difference in performance regarding primary and secondary stability on two kayaks otherwise of the same design? Thanks for any info on this.
Forget The Chines
how does the shape of the hull look overall in a cross section? If it’s more “V” like, than you’ll you have more secondary over primary stability. If it looks like this “|_|”, where the hull bottom is flat, than it has more primary than secondary.
Since your profile says to take your messages with a grain of salt, I guess I’ll do that. Your explanation was a non-explanation. I suspect there is a more of an answer to this question than you imply. The question was not about general hull shape.
"Otherwise the same" is the tricky part. If you faired a multi-chine hull to produce a soft chine with similar cross-sections at each station, the performance should be similar. But it’s hard to change just one aspect of a design without affecting other variables. Heck, where do you draw the line to fair the sections? Peak of each chine? Midpoint of the panel?
Some people claim that multi-chines offer more dynamic resistance to rolling, due to the increased drag, but the static stability should be similar for similar cross-sections.
When this subject comes up the usual conclusion is something like “Don’t worry about the chines – just paddle the boat and see if you like it.”
The soft chined boats that I have tried seem to have little primary or secondary stability, but they are supposed to be faster. The multi-chined boats had slightly more initial and secondary. The hard-chined ones had relatively lower initial stability and a very solid secondary. The problem is that these are all gross generalizations. There are many more parts of the hull design that have a great amount of effect. As Sing so aptly pointed out, there is V versus flat bottomed. There is also the question of how far forward the beam is taken. On the soft chines, what does the curve look like? On the multi-chined, how many chines are there, and what is the angle between them. On a hard-chined boat, how much of a V bottom is there and what angle is the chine? Are there any bulges or concavities? The sides of the hull, are they flat? concave? both? Many, many variables.
And, The Answer Is Most
apparent when you sit your butt in one boat and compare it to another, and another, and another...
I think the whole "hard chine vs multichine, vs soft chine" doesn't say one iota of anything. You need to know at the cross section of the boat and where the waterline is relative to the paddler.
But all of us "grasshoppers" have to go through the process of trying (and owning) a lot of boats before the jargon no longer has its mystical hold. I know that's what it took me. :)
Brother sing is humble,
but you should play nice with him, and he is quite accurate. He does design and build boats, you know.
Some multi chined hull designs give you really good feedback as you go from level to level on the chine. Although I do not find them beautiful. I like them OK especially whe hulls get in the 23-25 inch beam range.
Bottom line from me, when you can feel it for yourself then it's time to choose. Otherwise spend more time on edge(practice balancing with paddle ready to brace and then take it sowly over the edge) and resultantly practicing self rescues, (if you are anything like I was before my flatwater roll came). You will develop the feel.
I found this helpful…
and will give you some graphic and written info. supporting what the folks are saying.
Might just be me, but I needed the illustrations to understand the effects of a hard chined boat on stability.
Be patient, you’re going to get some really good poop from lots of experienced folks.
A hard shine boat is a very different
animal from most multi chine designs. The multi chined boats that I have spent time in (Mostly looksha 4 and 4hv and narpas (I think they were multi-chined?) are much closer to soft chined boats.
Check out Nick Schade’s pages . .
on stability and kayak design! There’s a lot of info here but even if you don’t understand everything on the page there’s a lot of interesting tidbits. Near the end of the page it gets into a comparison of various hull cross-sections.
Good luck, enjoy!
PT I agree that for mere mortals our personal and quite portable butt-o-meters are the most accurate devises for measuring stability according to our personal standards.
these guys do know what they are talking about. I also believe the old rump o meter will tell ya which boat is best for what ya want.
Hard vs Multi Chines…
and a slice of lime
actchully sing is telling you the up and up. Chines are a design element,a part of a whole. It’s possible for one “whole” to be different than another “whole” and have the same identifying element called a “chine”,or “multichine”.
The Pygmy link below is accurate information as it applies to Pygmys kayaks.
and if that’s not confusing enough
go to this site and read the description of hard-chine vs. multichine. If you slog through the vague statements you’ll find that it says exactly the opposite of what the Pygmy site says regarding the two. So you’re not alone.
There are a lot of funny things said by people in the position of marketing that’s basically gobbledygook. Without specifying the nature of the rocker, crosssection shape,and whether the moon is in the seventh house you really can’t come up with a generality of two hulls (wholes) by comparing one specific element(chine shape).
is kind of a marketing gimick in plastic/composite design kind of like tail fins on cars,or to introduce hull stiffening feature like Necky Lookshas,the Lookshas handle the way they do because of rocker. Soft chines,well those are like hardchines but softer.
I never could figure out why a composite/RM boat would have multichines…
Aren’t your sirocco and my explorer
soft chined boats? I think they both have good secondary stability
Yes, my Sirocco is a soft-chined boat, but it acts almost like a hard-chine. Secondary is incredible. That’s why I said above that it can really depend on the soft-chine’s curve. Some friends of mine have a pair of Corona’s which have what I would call serious soft-chines. It looks like a constant curve and the initial and secondary are low. The curve on my Sirocco (to me!)more approximates a hard-chine boat. It can all get pretty confusing, glad I’m not a designer!