Appendix VII – Multihull Capsize Protocol

As always, the hardest part is facing squarely the potential for calamity and doing the simple things ahead of time to make coping with capsize easier. In the unlikely event of disaster you will be prepared.

Chris White,
The Cruising Multihull


Required Reading

The most authoritative text on dealing with capsize is contained in Jim Brown's book,The Case for the Cruising Trimaran by Jim Brown (Jun 1, 2010). Also of great value is Chris White's excellent work,The Cruising Multihull (Sep 1, 1996).


Psychological Preparations

The vices of the unpredictable sea notwithstanding, the medium of the ocean beneath is supportive of life. An exuberant variety of fish thrive in it, even thousands of feet below the surface. Mammals like whales and dolphins call it home. We human mammals spend the first nine months of our lives fully immersed in the saltwater environment of the womb. We enjoy going to the beach and swimming in the ocean later on in our lives. No doubt in a generation or two we will be living beneath the sea, farming its bounty, mining its beds, and perhaps even learning how to communicate with whales and dolphins. There is no reason for us to fear such a medium. There is no reason for us to perish when we are accidentally immersed in it.

Multihull capsize need not be the end of the world. It may be an inconvenience, a discomfort and a temporary setback, but it is not the end of the world. With seamanship and the proper use of sea anchors and drogues the chances of multihull capsize can be greatly reduced. And even if a multihull does capsize, it need not result in loss of life. But unless the crew is prepared to deal with such an eventuality lives may be lost. Loss of life is by and large caused by two things: 1) Drowning. 2) Hypothermia.



We humans need oxygen to survive. If our lungs become clogged with water we may expire from oxygen-deprivation. Those who die of drowning likely do so because they are not wearing a life jacket and can no longer keep their heads above water. Safety experts, the Coast Guard and the Navy will all tell you that those who wear life jackets consistently outlive those who don't. The slogan of the California Department of Boating and Waterways is very much germane to the present discussion:


Wear your life jacket,

It's your friend for life!

Wear your life jacket during and after deployment. Don't take it off after you have deployed the sea anchor or drogue. Keep it on for the duration of the storm. If you don't like bulky life jackets there are other PFDs (personal flotation devices) on the market that have the look and feel of an ordinary parka. Some even come with integral safety harness.

Most of those who die after falling into the cold sea die of hypothermia. Most cold water drownings are in reality caused by the hypothermia-related loss of gross bodily functions - the use of arms and legs to tread water and keep afloat - and loss of consciousness.


Hypothermia: The Real Killer

The medium of the ocean is supportive of life. Dolphins are happy to spend their whole lives in it. We humans have bodies that differ from those of dolphins in terms of thermal requirements, heat tolerance and cold threshold. We are geared to survive in a different temperature environment.

The mean core temperature of the human body is around about 37° C (98.6° Fahrenheit). Thermoregulation is the complex process by which the brain, the skin, the myriad thermal receptors, the arteries, the heart pump, the lungs and other organs regulate and maintain this temperature within a 1-2° C (1.8-3.6° F) margin. Even a 2 or 3° change in core temperature can have disastrous consequences. Every time the core temperature falls beyond 2 or 3° there is potential for a life-threatening breakdown. Muscle rigidity can be expected below 33°C (91° F). Loss of the use of limbs at 31°C (88° F). Unconsciousness and heart failure at 29°C (84°F). Certain death at 25°C (77°). In cold waters all of the above can occur within a few minutes.

The human body can quickly lose a great deal of heat in cold water. This hemorrhage of heat and energy results in reductions in core temperature. As we lose more and more heat, bodily systems work slower and slower until they are barely functioning.

Unless warmth can be retained/restored, our complex biological systems shut down, our cells begin to die and death from hypothermia will quickly ensue.

It is not within the scope of this publication to provide a detailed explanation of thermoregulation and the onset of hypothermia. Suffice it to say that in a physical sense we are creatures of temperature. Whether we live or die depends on whether we can maintain the core temperature of our bodies within narrow design limits. This is true of all creatures.

A dolphin's body is geared to function at a lower temperature than ours. Remove the dolphin from its element on a warm day and its core temperature will quickly rise. This is why stranded dolphins have to be rinsed down and provided with shade. Without constant rinsing and shade the creature will quickly expire from heat stroke, as quickly as a human expires from heat loss when immersed in cold water.

But this is where we humans have dolphins at a disadvantage. Delphinidae don't possess the technological wherewithal to construct artificial, thermoregulatory enclosures around their bodies. We humans do. That's why we have invented immersion suits. We can survive hypothermia in the artificial skin of an immersion suit.

Note that when the trimaran Gonzo capsized in File S/C-5 one of the first things that Walter Greene and crew did was to put on their immersion suits.

Note also that after deploying their para-anchor in a Force 11 storm in the Gulf of Alaska, one of the first things that Rick and Linda Kasprzak did was to put on their immersion suits. Wrote Rick Kasprzak, "...we were dressed in our survival suits and had the catamaran ready so that if we flipped, we could have access to our EPIRB, survival food and water," (File S/C-8).

On the way to Hawaii in his little open trimaran, Victor Shane was in his wetsuit for two days when he ran into gale force winds in the outer coastal waters of California. On the way back he was in his wetsuit again for a day and a half when he ran into a gale west of San Francisco.

A wetsuit can trap a great deal of heat. Divers can remain submerged in icy waters for many hours in a well-designed wetsuit.

But wetsuits are difficult to get into quickly. Immersion suits are easier. Unlike wetsuits, one can get into an immersion suit fully clothed, wet or dry. Like wetsuits, immersion suits function as full body flotation modules as well. One can survive for relatively long periods of time in cold water in the "survival pod" embodied by an immersion suit.

When the fishing vessel Cloverleaf rolled and sank off the Alaska Coast in 1980, Captain R.T. Laws survived 27 hours in 2.7°C (37° F) water in a Bayley Suit. "The Bayley Exposure Suit saved my life," said Laws, "without it I had no chance for survival." Without it he would have expired from hypothermia within a matter of minutes.

DON'T PUT OUT TO SEA WITHOUT IMMERSION SUITS. They are not that expensive. Bayley Suits (and similar) have been seen on sale for around the $300 mark. This suit has been approved by both US & Canadian Coast Guards and has the approval of many other international safety organizations, including SOLAS (Safety of Life at Sea Convention). A quick search online for "immersion survival suit" will produce many useful results. Three hundred dollars is not much to pay for a long and prosperous life after capsize.

There are other thermal enclosures on the market today. Mustang Suits, heat retaining storm jackets, etc. Again, a wetsuit is a likely substitute. Along with the mask, snorkel and fins, it is an absolute necessity on any long cruise. A lighter surfer's wetsuit is better than nothing. Snowmobile suits or waterproof skiing attire may keep a sailor warm. At the very least layers of clothing may ward off hypothermia in warmer climates.

When it comes to rapid heat loss the human head needs major attention. In cold conditions an unprotected head is for all intents and purposes a heat drain valve left wide open!

This is because skull and bone are much better conductors of heat than tissue and muscle. Huge arteries carry warm blood to the brain where the heat can be quickly conducted away into the environment.

In fact, hypothermia studies have shown that fully 50% of the heat that the body loses escapes from the head area. So in theory, at least, if the head can be protected from heat loss by wearing a thick neoprene diving cap one might be able to double one's survival time in cold water. A large diving mask would also help retain heat. At the very least, several woolen watch-caps worn under the hood of foul weather gear - or a storm parka - might extend survival time until rescue.


Multihull Classifications

Foremost among our "thermal enclosures" is the interior of the boat itself. In so far as multihulls go, capsize may invert that enclosure but in most cases it can't sink it outright. Depending on the basic classification, the enclosure may or may not remain the most viable and life-sustaining environment after capsize - the one that provides the easiest access to food and water stores as well. There are only two classifications:

1: Capsize habitable

2: Capsize non-habitable

Because of the air trapped in the outer floats, most trimarans are capsize habitable. In File S/T-7 we find John Glennie and crew surviving 118 days in the inverted hull of the trimaran Rose Noëlle, in all that time having access to water, food and shelter. A minimum dry interior height of 3-4 feet is required to make a capsized trimaran - or catamaran - habitable. Living comfortably inside such a tunnel area calls for creative ideas. Jim Brown's "capsize hammocks" would provide dry, comfortable places for an individual to sleep in, for example.

Catamarans present a different scenario. Because they float lower when inverted, and because the large main salon will usually be fully submerged, most catamarans are not capsize habitable. In File S/C-19, when the catamaran Bayete capsized the occupants seem to have been quickly forced outside, finding themselves on the slippery underwing deck area between the hulls. Without tethers and handholds they were quickly swept overboard and overcome by hypothermia.

YOU MUST FIND OUT WHAT CLASSIFICATION YOUR BOAT FALLS UNDER. Talk to the naval architect or the multihull designer. Make certain that your boat is in fact unsinkable - a few multihulls have been known to sink outright!

Ask the designer or builder about the level at which the vessel will float after capsize. Ask him about watertight bulkheads, air pockets and potentially habitable areas. Find out if there will be enough interior space to survive in after inversion, and if so, exactly where. One of the big challenges is finding a horizontal surface that will be above water level and on which one can lie when capsized.

Designer Chris White has solved this problem in his catamarans by building a habitation module into the bows of his larger cats. These provide a seal-able pod into which one can retreat in the event of a capsize.

If you are having the multihull built, find out if certain areas can be filled with foam to provide additional buoyancy. There are many nooks and crannies on modern catamarans. Filling them with solid foam will make the yacht more seaworthy and increase odds of survival in case of collision with a ship, for example. It will also allow the boat to float higher when inverted.


Capsize Habitable

If you know for certain that your boat is capsize habitable, try to imagine what it will look and feel like moments after capsize. A short while ago the boat was upright and its motion was quite lively. Now that she has overturned she has settled lower in the water and has the more heavy, stable feel of a submarine. Try to imagine what you will do as cold water begins to rise around your ankles. Did you have a serious chat with the crew or family beforehand, about capsize not being the end of the world? Did you remember to give a reassuring shout of "DON'T PANIC" shortly after the boat rolled over?

The first few minutes will be critical. Remain calm. Remember, seawater is a life-supporting medium - fish live in it. Don't rush to blindly swim out from under the inverted hull - there may be a tangle of sheets, lines, stays, sails, broken mast parts, boom and other debris dangling under the boat. THINK FIRST. ACT SECOND.

If you must make your exit from under an inverted hull, plan on a safe route ahead of time. In daylight, diving goggles will enable you to pick your way.

NOTE: if you are wearing flotation gear, or an immersion suit, or a wetsuit without diving weights, the positive buoyancy of what you are wearing will tend to float you up and make you "stick" to the underside of the inverted multihull. You can still make your way out, but you may have to do it on your back, pushing off with your hands.

What will the interior look like when upside down? Will everything fall out of its place, or did you make a point of securing everything before you put out to sea? Will the cabinet doors and drawers open and disgorge their contents, or did you install positive latches on these? Will the floor boards tumble down and turn the interior into an obstacle course? Will the wet, heavy carpet float down onto your head like a death shroud? Will the unsecured foam cushions float about and try to smother your children? Will wet blankets twist around your ankles like thick seaweed? What does it take to secure such items? What does it take to plan ahead for such things? Not much.

The bilges will now be the roof over your head. Did you devise a way of removing and storing the floor boards in an orderly fashion? Did you secure a diving light and Cyalume light sticks in the bilges? If capsize occurs after dark you will need immediate access to emergency lighting. Remember, all the overhead cabin lights will now be underwater, and the electrics will probably have failed in any case.

Do crew members have easy access to their immersion suits? Do they know where the EPIRB is located and how to activate it?

As far as a capsized multihull is concerned the experts generally agree that it is better to stay with the boat. In coastal situations the EPIRB should bring help before too long.

In long, drawn out survival situations offshore, a man-size hole may have to be cut in the roof (bilge) of a capsize-habitable multihull. You will need tools - axe & keyhole saw.

Experts all agree that this "hatch" should be cut as high as possible. Don't cut it low or every wave will dump more water into the inverted hull. The hole that you cut out should be like a submarine hatch, high out of the water, a place of relatively dry ingress & egress, the all-important perch from which crew members can take turn standing watch, shooting distress flares, waving flags, hoisting radar reflectors on the ends of poles, etc.

Cutting out this hatch may mean violating an airlock, after which the boat will settle a little lower. Talk to your multihull designer or naval architect about this. Ask specific questions - "Where should I cut the hatch? How much lower might the hull be expected to settle afterwards?" Work together with your designer or naval architect. These talented individuals have emotional ties to their brainchilds. They care a great deal about the lives of those who venture offshore on their boats. They have vested interests in your safety. They don't want you to come to harm on one of their creations.


Capsize Non-Habitable

If you are absolutely certain that your boat is not capsize habitable then you must invest in a good life raft. Storage position of the raft canister is critical. THE CANISTER SHOULD BE EASILY ACCESSIBLE WHETHER THE CATAMARAN IS UPRIGHT OR INVERTED.

Storage location will differ from boat to boat. Some experts suggest that the canister be secured to the trampoline and its hardware topsides, where it will be accessible from both top and bottom - one would need a knife to cut the trampoline after capsize. Some life rafts, notably those designed for aircraft and commercial vessels, have an auto-inflation feature. Such a feature is not desirable as the raft may auto-inflate beneath the multihull after capsize.

Some catamarans may need a factory-installed escape hatch in the topside of one hull to allow safe exit after capsize (many already do).

Of course once outside, the best life raft in the world won't do you any good if you are instantly washed out to sea. The underwing of an inverted multihull is a very slippery place to be in heavy weather. Some sort of lifeline is imperative. You must devise tether systems, handholds and restraints that will (a) keep you from being swept off the inverted hull, and (b) allow you to make your way to the life raft. At the very least, a length of knotted rope secured on deck and running longitudinally beneath the wing can serve as a lifeline after capsize. A dozen or so stainless steel padeyes must be thru-bolted to the hulls close to the waterline. These can then be used to hook tethers and harnesses to.

Most safety experts agree that after successful life raft inflation the best course is to keep it tethered to the still floating mothership. For search and rescue purposes an inverted multihull is much easier to spot from the air than a small life raft.

The use of red bottom paint on the hulls will make spotting easier as well, as will the use of orange paint on the under wing. Paint sections of the underwing with an orange checkerboard motif, an "SOS," or a large "V."

Staying with the mothership will also mean access to life-sustaining food, water, clothing, tools etc. You will need mask, snorkel and fins for diving into the hull to retrieve food and water. At least part of the total fresh water carried by the mother-ship should be in plastic jugs with screw on caps (as opposed to lift-off caps) so that it can be carried to the raft.

Tethering a life raft to an inverted multihull is not as easy as it sounds and may require much pre-planning. In heavy weather a tether might rip a single attachment point right off the rubber raft. MULTIHULL LIFE RAFTS MUST BE EQUIPPED WITH MULTIPLE ATTACHMENT POINTS.

Raft manufacturers can easily install additional attachment points. No harm in asking them to install a dozen large, specially reinforced ones on your raft. One could also rig some sort of collar that would go all the way around the raft, perhaps from trampoline netting material, or a sail. A working jib, properly rigged, might make an excellent "diaper" around a raft. Look alive and be creative. Don't just sit in the raft and watch it fall apart. For example, you may be able to "spiderweb" the raft between the inverted hulls (to use a term coined by Jim Brown himself).

Check all raft attachment points regularly for chafe and wear. In a worst-case scenario a raft may have to be temporarily hand-tethered (someone inside the raft physically holding the tether by hand), while someone else is trying rig another tethering scheme.


Safety Harnesses

 CAUTION: SAFETY HARNESSES MUST BE RELEASABLE UNDER LOAD. Make certain the tether portion of the harness has two clip-type attachment - one for clipping onto the boat, the other for clipping onto the harness worn around your chest. The chest attachment must be releasable under load in case you get trapped under the boat after capsize.


Fuel and Water Tanks

All tank installations should be carefully examined to see if they might leak after capsize. Any gasoline leaking into the interior will make habitation impossible, contaminating everything else as well. Fuel and water tanks should have shut-off valves. The normal filler cap on deck and outboard vent pipe affair should not pose any problems. The water in tanks may not be accessible after capsize. Adequate water should be stored in gallon bottles with screw-on caps. These and other plastic water containers should have an air gap so that they will float. Make sure that the lockers in which they are stored will not open by themselves when inverted.



 CAUTION: Conventional batteries can emit poisonous chlorine gas when immersed. The gas is produced mostly by the lead battery terminals, so one should avoid having them come in contact with saltwater. Think about capsize when deciding on where to install batteries. Ideally they should be installed away from living quarters and positioned so that they will be above the waterline in the event of capsize.

Best idea: Replace conventional batteries with sealed gel batteries or, better still, modern Lithium (LiFePO4) batteries. Always keep the battery terminals well-greased as this will waterproof them and result in less chlorine emission.


Calamity Pack

No yacht should put out to sea without a calamity pack. A calamity pack is a container or rugged bag containing the essentials of survival. It is secured in an accessible place so that it can be one of the first things to go into the life raft in the case of a sinking monohull or capsized multihull.

The following is a suggestion list of some of the items that might go into the calamity pack. Note that unless the ship's budget allows for duplicate purchases, some of the expensive items on the following list will have to do for both boat and life raft.

  • WATERMAKER (hand pumped)


406 MHz EPIRB (Emergency Position Indicating Radio Beacon): Your surest bet for a quick rescue. In this day and age an EPIRB can summon help from almost anywhere on the planet via satellites. The most modern ones transmit a GPS position, which means the rescue services know exactly where you are. Most EPIRBs will continue to broadcast for a few days, after which the battery will have to be replaced. CHECK THE BATTERY'S EXPIRATION DATE and test once a year according to the instructions.

LIGHTS: At least one good, expensive diving light. Several smaller utility flashlights. Two hand-held strobe lights. The above will require adequate supplies of new alkaline batteries. Cyalume sticks. Candle lantern, candles & waterproof matches.

FLARES: Main parachute flares should be the bigger, rocket-propelled ones (not the ones fired from a pistol) as these are your best bet for attracting attention. In addition you will need a good assortment of smaller pistol-fired flares, Roman candles, etc. Shooting off flares carelessly has been known to cause face burns and raft damage. Practice firing one of each kind on land. Face away from the wind when firing. Use gloves or wrap your hands in some protective material as you do.

RADAR REFLECTOR: Hoisted up on a spinnaker pole or fishing rod, this inexpensive item can be an important search and rescue aid. All search aircraft and rescue ships use search radars. When purchasing a radar reflector for the mast, purchase another one for the calamity pack. At the very least a very effective radar reflector can be made by stuffing loosely crumpled aluminum foil into a net shopping bag and then raising it up on a fishing pole.

HAND-HELD VHF (waterproof): An absolute necessity for summoning assistance from passing ships, and for providing information about injured persons, or information about other critical considerations prior to and during rescue by ship or helicopter. After the EPIRB pin-points your location, the hand-held VHF will be your main channel of communication with those who are coordinating rescue operation. If possible, get one with DSC capability as that allows you to transmit a Mayday alarm with just one button. This alarm will sound on the bridge of nearby ships, waking them up to your voice transmission.

WATERMAKER: This technological marvel uses a hand pump to force salt water through hi-tech membranes to produce fresh drinking water. In prolonged survival situations is may very well turn out to be the single most important piece of equipment in the calamity pack.

PROVISIONS: Refer to Offshore Checklist (Appendix VI) for suggestions. The list of things to put into the calamity pack could include anything and everything, or just the bare necessities. At the very least it would be easy for one to collect a few canned goods, seeds, nuts, cereals, some bottled water, a can opener, a spoon, a flashlight, a signal mirror, some batteries, a candle lantern with candles, waterproof matches, Bic lighters and Polaroid glasses and place them in a waterproof plastic container.

CLOTHING: Emphasis should be on items that retain heat. The list should include neoprene diving caps, woolen hats and hoods to keep the head area warm. It should also include a few thermal blankets. These lightweight, waterproof "space blankets" have an aluminized lining that reflects heat back to the body.

MEDICINES: As necessary (consult your personal physician). You will need spare prescription glasses if you wear them. You will need some antiseptic cream, bandages and bandaids for cuts, bruises and salt water sores. Chapstick, aspirin, laxative, antacid tablets, sea sickness pills, etc.

TOOLS, ETC: Mask, snorkel and fins are absolute necessities. The ones that go into the calamity pack need not take up too much room. The fins can be the smaller, recreational ones. Miniature diving goggles can substitute for a large mask. Don't forego the snorkel as this item will allow you to swim in relative comfort for longer periods on the surface, without having to constantly gasp for breath.

You will need a telescoping fishing pole, line, hooks and lures. Hooks and lures must have steel leaders as the sort of fish you will be catching may bite through nylon line. A small spear gun or diving spear will help bring in the tasty fish that hang around but never bite. Keep all sharp hooks and spear tips away from the raft.

A utility knife and small sharpening stone should be in the calamity pack, along with one high quality - stainless steel - survival tool (pliers, knife, screw driver, scissors, etc. rolled into one). A roll of duct tape should be included, along with lengths of rope and string.


Waterproof Containers

Many of the items listed above must be stored in waterproof containers, sealed plastic jars or several layers of waterproofing material, or they will be useless in short order. Flares and batteries are especially susceptible to salt water degradation. The hand-held VHF can be housed in a specially designed waterproof bag. Other types of waterproof pouches are now available from marine outlets. Indeed, the whole calamity pack could be stored in a 'dry-bag', which will also float.

Wrist Lanyards

ATTACH WRIST LANYARDS TO ANYTHING AND EVERYTHING THAT DOESN'T FLOAT. The best survival tool on earth will disappear if it falls overboard. The calamity pack itself should be equipped with a stout lanyard for attaching it to the mothership or to the life raft.

Capsize Preparation Checklist


Vessel Description:


Vessel Name:




Designer's Address:




Classification determined to be:




  • Immersion Suit/s
  • Emergency Hatch Cutting Tools
  • Life Raft (Attachment Points).
  • Safety Harnesses (Releasable Under Load)
  • Tethering Systems (Lifeline Padeyes)
  • Fuel & Water Tanks (Shutoffs)
  • Batteries (Sealed Gel)
  • Calamity Pack:
  • EPIRB (Battery Date ___________________)


Jim Brown: "In all probability, your capsize preparations will never be put to the test. But once made, adequate preparations yield perpetual benefits in peace of mind." (The Case for the Cruising Trimaran, courtesy of International Marine Publishing Company).


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