These guys got some cajones. And well-beaten kidneys.
Interesting view of boat design regarding capsize prevention.
I posted a bit back about an idle - and maybe impractical - idea I had
for inflatable gunnel bags.
Looks like buoyant gunnels are built into this boat.
Here's an excerpt for those who are not allowed on the site - it
requires free signup. You can google most of it up using this
subject, but maybe not this new article from Boatest.
Some interesting videos, including one taken from a UK S&R chopper of
the boat in 12' seas.

http://www.boattest.com/Resources/vi...px?NewsID=3836

"As soon as you flood the bilge of a boat it starts to become
unstable, Brown said. When the cockpit is flooded the boat can easily
capsize which is why we put two 3-1/2 scuppers in the transom of the
boat. Brown went on to say that he used rubber exhaust pipe flappers
to cover his scuppers on the outside and act as a check valve.
Once the cockpit of a small boat is flooded, the free surface effect
of the water as it moves from side to side unfettered by baffles will
usually capsize the boat.
I filled the hull with foam flotation and placed it on the outside in
the gunwales to make the boat harder to flip, Brown said. I knew the
boat would never sink no matter what happened."

Also of note:
"In fact, the transatlantic boat seems to have been impervious to the
free surface effect simply because there was very little room for
water in the cockpit. The foredeck of the Intruder C-21 is a flat
casting platform with six hatches for storage. The cockpit was filled
with numerous large containers of fuel, water and supplies, leaving
little space for anything else -- including sea water!"

So there's one solution to avoid shipping seas - fill your boat with
"stuff!" Better have it lashed down well though.

--Vic