A severe knockdown or capsize is the worst-case scenario a lot of cruisers don't want to think about. Advances in boat design and hull testing since sport-changing events like the 1979 Fastnet disaster, plus vastly improved onboard access to heavy weather information, have allowed most boats to avoid the really bad conditions that can chuck a boat on her beam-ends. It's not a situation many will predictably face.
And yet the seas aren't predictable, and climate change promises more storm activity, as warmer oceans have more energy to release into the atmosphere. Tropical storms may be bigger, last longer and go farther than we've accepted as customary into higher latitudes. Unseasonable gales may gradually alter pilot charts refined over 200 years of observation.
The prudent sailor recalls the old phrase "battening down", and starts to plan on modifying his own boat.
I think that if one focusess on surviving a roll or a bad (90 degrees or greater) knocking without severe damage, rather than attempting at all costs to avoid it, one will have a happier and longer life in some of the more challenging seas on the ocean. Keep in mind that a capsize need not be a complete inversion or a 360 degree roll, to my knowledge, but includes a 90 degree or greater knockdown. Anything that makes the galley the floor is going to shift things and probably bring water, perhaps a fair amount, aboard.
This means attention to details like thoroughly secured stowage, positive tie-downs and locks, keeping the decks clear and clean, and installing gasketed, doggable companionway hatches and storm shutters for the more vulnerable parts of the boat.
I had an idea for routing all the water and fuel tank vents into two common pipes, leading to goosenecks mounted on either the pilothouse sides or the roof of our boat (it's not an original idea, but it's utterly out of favour on modern yachts). This is to avoid downflooding of sea water should the boat get knocked down or rolled. As part of securing for heavy weather, you manually shut off valves or cocks on the fuel and water vent lines, and on the engine exhaust. You seal all dorades and things like Nicro vents.
You dog the hatches shut and if possible, cover them and batten them. You slide in storm shutters. And so on. This is on top of securing all stowage and provisions, all floorboards, etc. Pump the toilet dry. Close ALL intake and outlet seacocks...you're not going to be running the engine or pissing anywhere but your foulies. Make sure you have drag devices of your preferred type and a means to both deploy and recover them. Set aside prepared foods and drink if you're in for a long blow; you can get cold and hungry without realizing it even in the tropics if you are standing in cool downpours and high winds long enough.
All this takes a lot of planning and, ideally, practice. If we practise crew-overboard drills, we should practise "storm drills" before the storm actually hits, like on a 20-knot run in the trades. Water ingress is what scares people, but it seems minor when compared to turning the saloon into a batting cage of jars and tins and tools in a knockdown. To me, a fairly avid reader of cruising narratives, bailing out the bilge is made a lot worse (not to mention hard on the pumps) when a sack of unsecured flour and a gallon of olive oil have exploded due to a violent, storm-fuelled lurch. I've read about "I was cleaning for days and still find evidences in crevices and corners years later" several times, and I can't stress too highly the idea that a boat underway in the ocean must be kept almost obsessively free of clutter and untidiness...because on a boat, most things can become projectiles if inverted.
If you can keep the sea out of the tanks and the boat, and keep things like giant wrenches or Honda 2000 generators from braining you or sacks of flour from exploding on the bulkheads, you can survive and recover from some pretty horrendous abuse (assuming you are tethered and haven't broken limbs falling the entire beam of the boat). But it demands the sort of contingency planning that a lot of people are unhappy to do, because it involves a fairly unemotional evaluation of a disastrous scenario in which the entire contents of the boat are rapidly rotated, along with the crew.
And yet as so many accounts of capsize and knockdown at sea indicate, these events are survivable and can even seem, if never trivial, unremarkable and not a voyage-ending event.
Here's the next fabrication project: a doggable companionway door.
The current Lexan dropboard doesn't even keep rain out from some directions, so I'm going for "bulletproof".
Due to the difficulty of making the top door section hinged (the pilothouse roof cambers down and I couldn’t open it 180 degrees without leaving a gap), I thought of making the top “door” a flap that hinges downward to allow air and communication in rough weather. The 10 inch gap should do this, and isn’t hard to screen, either.
The doors are to be 1/2 inch aluminum (although I'm beginning to think either a frame-backed 1/4" will suffice, or even a laminate sandwich of plastic and metal), and will be isolated from the frame by bushings and nylon gasketing. They will have four doggable handles and locks top and bottom. The top flap will have a rubber “shock strip” so that it doesn’t mar the bottom door, and the bottom door will open to the right and will positively latch open to the aft wall of the pilothouse. Gasketing all around. The sliding hatch will drop into place with a “lip” of gasketing to mate with the door flap. Dog it down and it should be pretty impervious to pooping waves.
The top flap would open outwards. It’s the only way to get an unbroken gasket along the perimeter (two sides and bottom sill). The sliding hatch would have a semi-rigid gasket that squeezed against the top flap when dogged down. This wouldn’t stop green water actually hitting the pilot house from behind full on, but I figure it’s as good as I can get and still have a gap for talking to the deck and for ventilation. Besides, if I have green water hitting the aft deck to that degree, a squirting gasket in the pilothouse won’t be my first concern, will it?
The top flap would have a rubber stopper of some sort to keep it from slamming, plus a positive latch. You would lower it until it clicked to the door, then the door would swing open until it latched to a stand-off latch on the stb. aft pilothouse bulkhead. At sea, it would be open most of the time, of course, as the very height of the aft deck keeps it dry. We’ve had some wash back from the sides, however, and in wet conditions, we’d have the lower door dogged shut and the flap down. Only in an extreme or during a storm run would we shut it entirely tight.
As for having four dogs, I can’t see doing it safely or securely with fewer.. You have to factor it that no lines pass that way, and that the thing will be latched open much of the time under an otherwise empty overhang. Picture a foredeck hatch either fully down or fully open...a fully open hatch has exposed doggable handles, but lying flat, they can’t catch sheets that are usually off the deck with the clew, aft of the hatch.
Feel free to comment or to propose alternatives.