# Can you interpret this graph for me?

http://www.riotkayaks.com/mediacenter/pdf/Tourlite15_SK_review.pdf

It shows “stability curves” for the boat, whatever that means. See the “Righting/Heeling Moments (Fixed Weight)” graph at the top right-hand corner of the third page (you have to scroll down).

Might want to explain it to me in monosyllables.

Thanks,

Donna

Basically…
The higher the curve the more secondary stability you will have. This is for different configurations of this boat only.

If you want a comparison of boats you will have to compare charts of different boats.

Here is one for a less stable boat.

http://tinyurl.com/3dmqmx

The official answer. > 1 syllable.
http://www.seakayakermag.com/PDFs/Kayak_Reviews_Info.pdf

no problem

– Last Updated: Aug-21-07 10:18 PM EST –

lighter people are more stable than heavy people. Putting weight in the kayak makes it more stable.
A broad curve provides more control near the capsize angle than steep curve.
It's a piece of data like weight, length or width or color. It might matter, it might not.

The problem with the graph is that it shows you what a DEAD WEIGHT does in the kayak. You are not dead weight. You are alive,,so there are attributes of handling you may prefer in one kayak over another even though you've identified one type of curve as more prefereable than another. I've looked at these curves for ten years and haven't found them predictive for what I'm seeking as much as validate something I've observed "wow,,that was a tippy kayak"

Tempest 170 and Explorer?
Anyone have these curves for the tempest 170 and explorer? Just for academic purposes of course. I gotta get around to subscribing to SK magazine.

Paul

as said above
Do not be confused by the paddlers weight in those curves, as LeeG pointed out calculations are for dead weight. That is, in the computer simulation the kayak is loaded with certain weight and the stability curve is then obtained. Depending on the quality of numerical algorithms, the weight can be placed at the center of mass, or distributed.

Now, it clearly shows that #3 curve provides the most stable configuration. Of course, this is computer simulation, not a real world situation. It would’ve been more interesting to load the kayak and then ask testers to evaluate stability.

But this was not done.

yep
The X axis (bottom) indicates how far you are tipping the boat in degrees. The Y axis (left) indicates the foot-pounds of correcting force pushing against the boat and trying to push it back to level.

As you tip the boat, the force increases. This force is trying to push the boat level again. At some point, you lean the boat too far. You are past the “tipping point”.

The force trying to keep you upright now decreases. It becomes even easier to tip the boat beyond that point.

These curves look pretty good as you see they increase gradually, the peak is kind of broad and then it decreases gradually as you heel over farther.

If the rise were steeper, it would mean more force required to to tip the boat initially. If the drop were steeper, it would mean once you pass the tipping point, the boat would loose stability much faster. So that once past the tipping point, it would basically flop over.

So best deal would be gradually increasing, broad peek and gradually decreasing. This will give a more friendly feel as you use the boats heeling forces while maneuvering.

a chart showing degrees of turning with a standard force representing a sweep stroke. This would be useful for comparing tracking/maneuverability. Then correlate that on another axis showing changes in turning effort with leaning.

I’d like water plane images of the hull at a couple angles.

You could also say
that experience trumps stability. You see people counting fish in what are reputed as “very stable” boats every day.

I would not put a lot of faith in those comparison charts. Use your own judgement.

monosyllables
it has a nice curve, seriously the downwards slope is VERY relaxed for it’s stability compared to other hulls. Not sure if that means anything but it’s nice to look at.

this one has the same beam but it looks much different.

http://www.seakayakermag.com/PDFs/Oct04_Chatham.pdf

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this one is 1/2" narrower,and is tippier

http://www.seakayakermag.com/PDFs/2006/Oct06Shearwaterspecs.pdf

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now this is interesting,22 1/4" beam and not much stability, and the seat is lower than the above boats. Apparently beam doesn’t tell one much other than the size of box you can fit the kayak into. The wider Stratus is tippier than the narrower Epic.

http://www.seakayakermag.com/PDFs/2006/August06stratus18stats.pdf

http://www.seakayakermag.com/PDFs/Endurance_stats.pdf

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check this out, the 26" wide Kestrel

isn’t as stable as the 24.25" wide LookshaV

http://www.seakayakermag.com/PDFs/Oct05Kestral140stats.pdf

http://www.seakayakermag.com/PDFs/2007/Feb07LookshaV.pdf

scratch and sniff
Yes, wet, week fresh neoprene in the morning… Nothing like it.

Ok, I think I get it now
Great explanations, thanks for the help!

can’t help it
being a wise *ss. There are characterisics that one can articulate about the experience of leaning a kayak,and kind of see that it’s reflected in the graph but I’ve yet to see that information being much more useful than “it’s a 17’ by 22” kayak" given that significant attibutes like weathercocking, pivot point and response to a sweep stroke at different degrees of lean aren’t even in the charts.