August, 22, 2010

Atlantic 57, Anna, Post Capsize Analysis

Whatever the cause, if a catamaran is capsized it will be imperative to rapidly shift gears from sailing to surviving. Fortunately, very few fatalities or serious injuries have been reported as result of capsize and if the crew stays with the boat the chances of being picked up in good condition are considerably improved over the alternatives - such as separating from the capsized boat in a life raft.

In the case of the A57, ‘Anna’, which capsized with two persons on board, Kelly Wright, the captain, found himself in the water immediately after capsize and made his way into the dinghy which had floated free and was still tied to the cat. Glen McConchie, the crew, was in the air space of the cockpit post capsize and made his way into the pilothouse, which was still only about half flooded immediately post capsize. Glen made his way to the misnamed “escape hatch” in the galley (misnamed because its function is mostly to aid someone outside the boat to get inside) and could see Kelly in the dinghy. They exchanged a “thumbs up” confirming each was OK.

Glen immediately thought of the EPIRB which was bulkhead mounted on the port side of the pilothouse. He dove several times to find it, without luck. Things were chaotic inside the boat, with numerous items such as cushions and floor boards floating around and heavier items rolling on the ceiling, which was now the low point. Adding to his confusion was that the port side was now the starboard and vice-verse. Once Glen got his bearings he located the EPIRB and turned it on.

NOTE: For many years the Atlantic Cats have used opening hatches as the escape hatch but about half of these hatches, no matter how carefully they are installed, leak when sailing in rough conditions. This leaking gets very tiresome, as salt water dribbles down the steps onto the cabin floor and requires constant mopping up. As a solution to that problem, on Anna we used an idea borrowed from the Lagoon catamarans. The hatch was made of tempered glass bonded to the hull in the same way that the pilothouse windows of the Atlantic cats are installed. To open the hatch the glass is broken with a special hammer mounted near the hatch. When tempered glass breaks it shatters into thousands of small nearly round pieces, and this seemed a reasonable way to gain access in a capsize and avoid leaks the rest of the time. Anna was the only Atlantic catamaran fitted with a tempered glass primary escape hatch, the others all have opening hatches.

Glen then went back to the escape hatch, took a fire extinguisher and hit the escape hatch but it did not break. Later he found the special hammer and beat on the glass with that and still could not break the tempered glass. At that point Kelly was secure in the dinghy so Glen went forward in what was the starboard hull to the “capsize pod”. This is the area forward in each hull that is separated from the main accommodation space by a full watertight bulkhead with a hatch located in the bulkhead at knee height. Since the original Atlantic 55 design in 2000, all the A55 and A57 have incorporated this feature where, if capsized, the crew can take refuge forward in the hull in order to stay dry and protected.

Inverted, the waterline inside the hull was still about 2 feet below the bottom of the hatch opening into the forepeak. Glen opened the hatch and stepped inside the forepeak where it was still completely dry. “Brilliant” is how he described the dry sanctuary of the “pod”, “…it worked exactly as it was supposed to. And I was very happy to be in there.”

After verifying that the “capsize pod” as he calls it, was dry and safe, Glen made his way aft into the overturned hulls. The water level varied from knee deep forward in the hull to almost chest deep further aft. He was able to gather a considerable amount of food, drinks and other useful items as they sloshed around inside the hull. Later he reported that once he had established himself in the “pod” he realized that he and Kelly would have enough to eat and drink and that they could survive for weeks if necessary.

The foredeck hatch, which was now on the floor in the “pod” leaked only slightly and Glen was able to periodically sponge out the water that accumulated. Also the air needed replenishment, so he removed the shower bilge discharge line from its thru hull fitting which provided a large flow of fresh air from outside.

The capsize happened in the late afternoon so it got dark soon afterward. Glen tried to make himself comfortable in the pod while Kelly rode the night out in the dinghy, still lashed to the upside down cat. The sea conditions were rough enough that occasionally the foredeck would bang as a wave lifted it and then slapped the deck hard. Glen was unable to find any flashlights post capsize and occasionally wanted light he did not have. It was a long night and uncomfortable but he was dry, warm and safe.

Meanwhile, Kelly had wisely secured the dinghy to the boat with multiple lines so that it could not be separated from the mother ship. Luckily the aft deck awning was stowed in the dinghy and he was able to wrap himself in that to stay warm. However, life in the dinghy was extremely difficult. In Kelly's own words:

“Riding in the dinghy was very uncomfortable. I compare it to being in a thousand fender benders, because the dinghy was ceaselessly slamming into one of the hulls and bouncing on top of the wing deck, then would float free only to fetch up with a violent jerk on one of the lines. Moreover, waves were constantly swamping me, ripping the awning out off my hand while I used the other hand to hold on. I counted for awhile and the most I was getting at one stage was about 12 seconds of peace before the next shock. The shocks were so violent that the 15-hp Yamaha outboard broke off its swivel and fell into the depths of the ocean... It was absolutely the most miserable time I have ever spent, and if I had been forced to suffer another day of that I don't know if I would have been strong enough to take it. I intended to try something different when dawn came.”

Kelly had the dinghy immediately available and was content to stay there although he would have been more comfortable and warmer inside. I am sure that if Glen and Kelly had spent another day in the capsized Anna they would have both settled in the pod.

The next day, by mid morning a ship was standing by to pick up Kelly and Glen.

Glen exited the hull by dropping down thru the deck hatch in the head. This hatch was about 18” deep in the water and only a couple feet from the outboard side of the hull so it was an easy matter to get out. In fact Glen had rigged a line with a float on it through the hatch to aid Kelly getting inside if they had to spend another day in the overturned boat.

What lessons can be drawn to make the A55/A57 cats safer in event of capsize?

Obviously, the tempered glass escape hatch that refused to break was a major problem and this type of hatch will never be installed in any of my designs again. I suspect the problem was more related to the tool provided to break the glass rather than the glass itself. Fortunately, the Atlantic cats sailing all have conventional opening hatches.

As I mentioned before, the Atlantic 55/57 design has always had provision for a safe, dry place for the crew in the forepeak separated by watertight bulkheads. However, in the 10 years since the first A55 was launched the general feeling developed that this cat was so unlikely to be capsized, that gradually the owners, including myself, started eliminating various features intended in the original design to make the forepeak area better suited to inverted habitation.

Now that we have had our collective noses rubbed in it- it’s time to revisit what was originally intended and what should be part of the outfitting for long distance ocean travel.

Attached is a drawing for the “capsize habitation area” or “pod” as envisioned in 2002. With the exception of an A57 intended for charter, all of the A55's and 57's were built with watertight bulkheads and hatches to divide the forepeaks from the flooded hull. What we know now that was not known then was where the inverted waterline would be after capsize. Calculations had shown that the inverted boat would float stern down and bows high - but exactly where the boat would stabilize was still somewhat uncertain. Photos of the overturned Anna produced evidence that the original calculations were pretty close. The real boat floated somewhat lower in the sterns and higher in the bows than I calsulated, which is actually beneficial to the task of living inside the boat. This drawing has the inverted waterline drawn as close as can be estimated from the photos of Anna and is consistent with Glen's estimate of the water level in the hull being 18” to 24” below the opening of the hatch into the “pod”.

The position of the hatch entry into the pod is good, and the pod itself should be dry if both the bulkhead hatch and deck hatch are closed, which they would normally be. That all works very well.

The drawing has pad eyes on the bulkheads in order to rig hammocks. Most of the existing A55/57s have these pad eyes installed, and they are easy to retrofit. Being able to rig a couple of simple hammocks would improve the comfort level a great deal, especially if the deck occasionally slams on waves.

Also shown in the drawing are a couple of thru hull fittings located above the normal waterline that were capped on the inside, so that by removing the caps, fresh air and light would be obtained. Glen needed air and was able to get it by removing the discharge hose from the shower bilge pump, but another means might be better. Based on Glen's experience, it seems that one 1.5” diameter thru hull would provide plenty of air.

Glen reported some initial obnoxious vapors from what he suspected to be the engine start battery but these were not so strong as to interfere with breathing and dissipated fairly soon. If the escape hatch had been open the aft part of the hull would have been well ventilated and I suspect fumes would not have accumulated. There was no diesel fuel leaking into the hull.

The sea water leaking into the pod thru the deck hatch was minor on Anna so the dedicated pump shown on the drawing can probably be eliminated in favor of using a bucket to do any required bailing. While all the A55/57's have different toilets and shower bilge pumps many of them have manual pumps located within a couple feet of the forepeak which in many cases could be used to pump out the pod if needed.

A “calamity pack”, is what Jim Brown called his collection of “must haves” in event of capsize. Whatever it's called it makes sense to have a certain base line collection of items packed in a waterproof container located in the capsize pod. It should also be TIED INTO THE BOAT, so that it cannot be sucked out of an open hatch and lost in a capsize or severe flooding.

Tops on the must have list is a 406 EPIRB. Whether this is located in the forepeak with the rest of the calamity pack is a decision for the skipper. Arguments can be made to have the EPIRB mounted in plain sight where all the crew sees it on a regular basis. But in any case it should also be attached to the boat in such a way that it cannot be lost.

The other “must have” items on my original list are:

  • Water, 5 gallons
  • Food, 21 man days rations
  • First Aid kit with any essential medications
  • Hand held waterproof VHF radio
  • Flares
  • Bucket
  • Flash lights
  • Basic tools to enable cutting hole in the hull for access or watch keeping
  • 100' light line
  • RADAR reflector

In the time since this list was written things have changed somewhat in that an EPIRB equipped with GPS allows accurate location of the EPIRB and has diminished the need for flares and radar reflector. But it would not hurt to have them. Also, with the GPS- EPIRB, the response time required to find a distressed vessel is often greatly reduced. This raises the question of how many days of rations should be included in the 'calamity pack' when almost certainly additional supplies can be salvaged from the galley and time to pick-up is unlikely to be more than a few days.

Every skipper will have his own variation of what is needed in the calamity pack, the point is to get some of the most essential items safely located in a place where they can be used in event of capsize.

Cold water poses another set of problems and risks. Hypothermia is the major killer in any type of boating accident. If capsize were to happen in a colder climate it is even more important to have a dry location inside the boat to await rescue. The capsize pod in the Atlantic 55/57 would be an ideal solution and offer excellent protection in cold water. Whether bulky survival suits should also be carried should be determined based on the possible conditions that the vessel might encounter. But some other lighter weight protection such as a wet suit or exposure suit could easily be stowed in the pod while on passage, just in case.

The Atlantic 55 and 57 offers great resistance to capsize as well as exceptional sub division to prevent flooding if holed by collision. Due to the use of thicker than normal foam cores in much of the structure not only is this catamaran unsinkable, it floats quite high when completely flooded or inverted. In addition each hull contains a separate watertight compartment forward which can provide a safe and dry accommodation space in event of capsize. With some basic preparation, this “capsize pod” can ensure complete protection and reasonably comfortable survival of the crew until pick up.

Righting the capsized cat?

The ship that was diverted to pick up the crew of Anna had the ability to re-right the capsized cat. Given the traumatic circumstances and physical stress that the crew of Anna experienced in the aftermath of capsize it is completely understandable that salvage of the cat was low on the agenda. But there was a vessel on site that had the ability. They would have needed to convince the captain of the rescue vessel to take the time required to perform a “tow over” of the catamaran and then bail the boat and tow it to harbor. A substantial quantity of money is likely to be the most persuasive argument and a call to ship's owner and the insurance company would probably be required. All of that would take time - which may de-rail the recovery process. Who knows if this feat will ever be performed, but it is possible and one day will likely be tried.

Capsized cats of large size have been recovered at sea before but never, to my knowledge, at the time the crew was picked up. The recognized, and in my opinion, the only way a capsized cat can be righted without significant damage is by use of the “tow over” method. This requires that a long line be attached to each bow and led over the underwing toward the stern. The towing vessel takes both lines in a bridle formation and applies a steady pull. The capsized cat, already floating in a “stern down” attitude, will start to rotate the sterns lower and the bows upward and then continue rotating 180 degrees until upright. Salvors are always dubious about trying this method and then amazed at how quickly and easily the cat is righted.

Once it is right side up, the cat will be full of water. Some of this water will likely flow out of the cat as the tendency will be to float a little higher after the “tow over”. What should happen next, in the ocean, is still conjecture. Ideally strong pumps would be available to bail the cat. If the seas are rough it my be difficult or impossible to bail the cat fast enough to make headway against water washing the decks. Other cats that have been righted in the ocean have been successfully pumped out. Once a fair portion of the water is removed the cat should be easy to tow a great distance- even at speeds of 10 knots and more.