Michael Daly wrote:

On 26-Aug-2003, Peter wrote:

Haven't used them in a real emergency, but the stability was more than
adequate with a person acting as a pretty limp body and moderate waves
including some whitecaps. The kayak was rather lightly loaded.
[...]
The only sponsons I own are built into the hull of my folder.


Are these the ones you did the test with?

Obviously not. I thought you might remember back a few posts where I
mentioned that the self-rescue class I attended had us practice a few
emergency scenarios with both sponsons and paddle floats. Based on the
experience there it appeared that the rescue sponsons (Sea Wings) had
advantages under some circumstances and I think they should still be
demonstrated. I don't remember exactly which model boat was used for the
'towing with sponsons' test, but it was probably about 16' x 23" and plastic.
I did not personally purchase them, so as I said above, the only sponsons I
own are the ones that came with my folder.

They aren't doing the same
thing as Timmy's sponsons, since they are inside the hull. Their main
purpose is to tighten up the skin over the frame and provide increased
bouyancy in the event of the kayak being flooded.

The internal sponsons on the folders I've seen are totally inadequate to
provide significant bouyancy if the kayak is flooded. Much more
substantial flotation bags and preferably also a seasock arrangement are
needed to ensure that the boat can be easily reentered and pumped out. But
although their volume is small, the location of the sponsons at the edge of
the hull does increase the stability of the boat if the cockpit is flooded

Most folders are high in stability due to hull shape, not because they
contain sponsons.

The two are not so easily separated. Sure stability is due to hull shape -
the water doesn't know what's inside the hull. But the external shape of
the hull is changed by the presence of the sponsons, making it bulge
outward above the waterline and making it more resistant to tipping past a
certain point when the sponsons are inflated. Whether that bulge is inside
or outside the nominal hull doesn't matter much from a stability standpoint
- in either case the bulge provides a righting moment if it is pushed below
the water on one side.