Did anyone but me notice on the YouTube video of the cat rescue that the 'access/escape' hatch in the starboard
hull is visible several times, and clearly under water with the sea breaking over the bridgedeck much of the time.
I too have read both the Rose Noelle
books, and Jim Brown's Case for Multihulls, in which he argues for several safety procedures and devices, such as ensuring that all lockers positively latch, and that nothing is left "lying about" as it becomes either a missile during the rollover, or flotsam inside the hull once inverted.
For the
record, the Callahan book of the Rose Noells saga sited that they slept on a 'bed' made of cans and lifejackets and other stuff they'd pulled from the wreckage, in order to keep their sleeping
gear above water.
So even with two hulls of approx 150% buoyancy holding up the central hull, it was still VERY marginal inside.
Cats are another story, as the openings from bridgedeck to hulls "assume" an 'always upright' stance.
If the
designer assumed 'potentially 180 degree stance' as being equally stable, they might then build in some kind of watertight door into the bridgedeck/hull
companionway openings so that each hull could in fact be made water tight, or nearly so.
One thing that has occurred to me (as a potential builder/modifier) is that no one ever talks about adding floatation foam to the upper surface of the hulls, which, when inverted, becomes the bottom, thereby adding sealed buoyancy right where it's needed most.
So rather than using 20mm foam, using 150mm foam for deck heads and decks, for example, with appropriately located hard points for deck fixings, might be advantageous. Or add 150mm foam to an existing deck
head inside (presuming
interior space available).
Extrapolating from Farrier's idea of an 'airbag' for the masthead, to enable the
mast be floated to the surface as part of a self-recovery effort, I had already come up with the idea of lightweight airbags fired by O2 canisters used for paintball
guns, which seem to be the optimum size for
storage (life jacket canisters being too small, and fire extinguishers too large) on a
small boat like an F22, but potentially if you had a CO2 fire extinguisher it could also be used as a filling source for airbags that could be inflated inside the hull.
But you'd need more than one, even if it was highly compressed. Not sure how to calulate the 'once pressure released' air volume, but would be pleased to hear from someone who knows how to calc that.
Looking at the 150Nm canisters for life jackets that fills a cubic foot or thereabouts, it ought to be possible to calculate what compressed volume you'd need to fill airbags that could displace water at sea level. I just don't have the maths! lol
If you look at the pics of most large cats when flipped they tend to float aft end down due to
engine and
fuel tank mass in those locations, so airbags in the REAR compartments might displace enough water to keep the aft end afloat and above the surface, thereby making the forward areas of either hull "livable".
Sort of like the Floatation Systems airbags, but inside the hull displacing water, rather than on the exterior supporting the boat upright.
If there were securable watertight doors to the bridgedeck then cat hulls could be made quite livable. But I still suspect that cutting a hole in the bottom of the upturned hull (as Rose Noelle did) would be required as the 'access hatches' will probably still be too close to the water if not actually under water, as they are in the vid further up the thread.
Some of the above points would also help mono sailors survive, for example, 180 or 360 knockdowns.
I read elsewhere the effect this had on the boat of a US couple who were 150 miles short of completing their
circumnavigation and suffered a 360 and a pooping (with companion open) that turned everything inside their boat into a churning
washing machine, dissolving paper
books into pulp which blocked their
bilge pumps.
They eventually abandoned their boat as it was unlivable (other crap happened to make it even less viable).
So, to be fair, it's not just
multihull sailors who perhaps ought to make better provision for "what might happen".
For example, closing
companionway doors might have prevented the 'washing machine' effect that wrecked the boat mentioned above. Seems simple, but reality is most people don't put all their washboards in place, so companionways on a mono are never watertight, and with a sliding deck roof, probably can't be made so.
Maybe mono desingers need to look at designs that have a domed deck with a slightly canted
single door companionway? Some of the smaller under 30' foot boats have such a design. The Top Hat 25' is one I see a lot, but there are others. It would be relatively easy to 'seal' such companion doors, especially from inside with
dogs forcing it closed against a seal.
So yeah, there's no one easy solution, and it's always horses for courses, but definitely the big, open condomarans are a 'fail' waiting for a flip.