Multihull Collision Survivability

Discussion in 'Multihulls' started by Skint For Life, May 12, 2011.

  1. boradicus
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    boradicus Senior Member

  2. boradicus
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    boradicus Senior Member

    I have heard of people using ping pong balls to lift old wrecks. Has anyone ever tried it?

    Also, one thing that we haven't discussed that much is the shock factor. Whenever an emergency occurs, whether at sea, or on land or in the air, there is a varying window in which the crew deal with shock. Some are less prone than others, but in the event of injury, hypothermia, discombobulation, etc, it may take time to get your head thinking reasonably. In such cases it would seem important to be able to put systems in place to create a better shock recovery window. Has anyone given thought to this, and if so what are your strategies and survival tactics? Flotation comes to mind first, of course, but in the meantime, there is hypothermia to contend with, and windows of time to save damaged portions of your vessel, rescue other crew, and so forth. There is also the redundancy issue. A lot of naval systems have built in redundancy so that in case of failure there is a back up. I am just wondering how these considerations may apply to multihull collision.
     
    Last edited: Jun 5, 2013
  3. MikeJohns
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    MikeJohns Senior Member

    You keep a monohull afloat just the same. The argument that multihulls float and monohulls sink is hype. Lots of multihulls are heavier than their total construction material displacement, they would be kept afloat by bulkheads, foam, PET bottles or ping pong balls...take your pick or invent what you like. The ballasted monohull is no different and they also have a lot more tolerance of downflooding because the enclosed volume is so high.
    Monohulls are able to be built a lot more robustly and gain a lot of insurance from that robustness.

    The catch with any light displacement boat whether mono or multi is that the hull doesn't have much reserve strength over and above the imposed sea loads. Then they should always have at least collision bulkheads.

    It's not just inversion you face but collision with objects which is what this thread was about. Another Cat sank here not so long ago a 50 footer from memory heading north and collided with an unknown object at night and sank, the crew were rescued from their life raft by a passing sailboat the following day. It's thought a whale might have broken the stub keel off one hull rubbing barnacles off, the Collision was felt as several soft bumps.



    This is a myth that needs killing, unless there are compartments you can access the majority of inversions in heavy weather at sea are resulting in fatalities. There are now numerous accounts from survivors of just how dangerous a situation it is to be on an upturned multi in heavy weather. Personal Epirbs and survival suits would increase your chances, as would having an accessible life raft equipped with Epirb.

    The same compartments that should be accessible for shelter should house emergency equipment. But designers don't take this seriously yet. On smaller multihulls it's not so easy.
     
  4. boradicus
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    boradicus Senior Member

    Survival Suits & Equipment Accessibility

    Mike, that is a good point. So, I suppose a good way to buy one's self and one's crew members time to recover from initial shock or injury related shock would be to have suitable access to emergency equipment, inclusive of shelter, life rafts, epirbs, etc, and that the flotation of the vessel work well in conjunction with the accessibility to the prescribed emergency equipment. You mentioned as well, survival suits. The thing that I notice that sticks out most in the Wiki article about them is that they are designed to be word at all times.

    I wonder if through-hull compartments have ever been considered for multihull design, which could be opened from either the top or bottom for accessing emergency equipment? :?:
     
  5. oldsailor7
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    oldsailor7 Senior Member

    Yes. This idea has been covered, particularly in the AYRS, back in the early 1960s.
     
  6. boradicus
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    boradicus Senior Member

    Do you recall what the pros or cons were? Thanks, Oldsailor7.
     
  7. cavalier mk2
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    cavalier mk2 Senior Member

    Not at all hype or myth Mike, the key word was GOOD. I suppose I should have specified having a chamber prepared but look to the Rose Noelle (sp). Most production boats aren't thought out in this way so for a very general statement there is some merit. We always carry immersion suits, I come from a commercial fishing background and subscribe to the tests done by Walter Greene the hard way.

    I did hear that manufacturers don't address this issue because they are wary of scaring off sales. Pretty damn silly as the survival aspects should be a marketing point. Proper preparation for inversion or collision should be undertaken by the serious sailor, my experience in tight spots is that the only people you can count on is yourself so prepare accordingly. Thinking this stuff through should be done. We had flotation in the monohull for example. It doesn't matter how many hulls you are sailing- each boat needs to be prepared correctly if you wish to increase your chances of survival when things go wrong.

    We keep everyone informed of catastrophe plans to avoid confusion if the **** does hit the fan. Making those plans in advance saves much time if you really need them, practice is important too. How fast can you get in your survival suit?
     
  8. cavalier mk2
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    cavalier mk2 Senior Member

    Borad, you need to get those books, these things are required on race boats and used by the smart cruisers. Sometimes saws are positioned in lew of hatches, prudent operators make sure everybody knows where the gear is but then many haven't done their homework.....

    For your book list you should get all of them but the Derek Harvey and Jim Brown will do the most good initially. I'd add both of Rob James books to your list,"Ocean Sailing" and especially "Multihulls Offshore". Do the homework.
     
  9. boradicus
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    boradicus Senior Member

    Thanks Cavalier! :) Will do!
     
  10. buzzman
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    buzzman Senior Member

    MJ
    I think it's fair to say that monos need to be constructed with full immersed to the gunwhales floatation capability, as it is patently obvious that if the hull fills the lead keel sinks the boat.....because mono designers also don't factor in enough positive floatation to counteract the mass of the keel as well as the boat and its contents.

    And by positive floatation I mean floatation that will still work if the hull is breached - so solid foam blocks or similar.

    No lead keel, the hull will float, as a few racers who've lost keels can attest. They don't stay upright for long, but they can float.

    Totally agree about the need for collision bulkheads and bulkheaded compartments filled with floatation foam etc, not simply air. If such a compartment is holed, or leaks, it is no longer floatation.

    Totally agree that most multi designers do not automatically include collision bulkheads, never mind large slabs of floatation foam (or whatever..).

    I have also noticed a deplorable lack of thought in especially big bridgedeck cats, of the need to keep the hulls watertight after inversion - for example, many have sliding doors or windows onto the cockpit area from the bridgedeck, which of course become sieves when inverted.

    At the very least, all ports, hatches and doors should be capable of being sealed from the *inside*, so that once the crew mannages to get inside thay can seal the hull and pump it out, making it a much more liveable space, even inverted.

    As Jim Brown argues in his book, there should be a compartment in the underside of each wingdeck containing safety ropes, water, high energy food snacks and a saw to enable the crew to cut their way in, if diving under the hull is too dangerous.

    Add a space blanket, and/or survival gear to minimise hypthermia - enough for all the crew, and inversions would be far less dangerous than at present.

    There should also be permanent handholds and safety harness attachment points fitted to the *underside* of wing or bridgedecks.

    Gales don't tend to last for weeks at a time, but three or four days, and generally they are only at peak force for a short period of time as the storm passes over (provided the hull is not drifting as fast as the storm, which kinda presupposes a deployable drogue of some kind to slow the rate of drift would also need to be included in the survival gear).

    So as long as the crew could lash themselves on, wrap up in something to keep the worst of the water off, and have food and water available to last a day and a night (at least) that ought to be enough to enable them to figure out how to get into the hull, andoonce there, as more than one capsized multi has proven, life can be 'relatively' comfortable.

    Sure, lee shores, reefs etc can drastically shorten the 'safe time' the hull can remain inverted, but as numerous examples have shown, boats left abandoned have a habit of turning up on a beach somewhere, eventually.

    For coastal sailing, sure - EPIRB and flares, holler for help. Lee shore, higher risk etc.

    But offshore I think we need to be like the Cook's and so on of previous ages, and be self-sufficient, rather than hitting the panic button at the first sign of trouble.

    This means that such off-shore multis need to be able to self recover....which no-one has yet demonstrated is possible without outside assistance.

    Hence why most offshore sailors choose monos.
     
  11. boradicus
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    boradicus Senior Member

    This is interesting...

    (Amazon review excerpt)

    ---
    Naomi James was not alone for her entire voyage. She did take along a cat named Boris. Actually, I think the tradition of having a ship's cat has grown ever since the First Statute of Westminster in 1275 stated that if any living thing (including man, dog, or cat) escaped from a stricken vessel, then it was no wreck. Well, Naomi did survive her voyage, but the cat was lost at sea.

    Naomi eventually received a Ph.D. in Philosophy in 2006.

    As for the author, he died tragically eleven days before Naomi gave birth to their daughter, Lois. In March, 1983, he went overboard from a 60-foot trimaran in eight-foot seas in the English channel. Although the boat did get along side, they were unable to recover him until it was too late.
    ---

    Evidently, all preparations aside, there were MOB and COB fatalities, inclusive of the author... :eek:
     
  12. cavalier mk2
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    cavalier mk2 Senior Member

    It was the deck netting Rob was let down by, he fell through after slipping while furling the main. Niaomi, pregnant at the time had a hard time getting the boat turned around though the crew who dove in after Rob was saved. I believe a helicopter rescue team recovered Rob's body. Safety gear needs constant inspection. In his case it did not perform as advertised. We use heavy commercial fish netting with good results and check it frequently.
     
  13. buzzman
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    buzzman Senior Member

    Rob James death was, like so many others, probably preventable had he been wearing an auto-inflating life jacket.

    As I understand it he wasn't wearing anything at life vest at all.

    Then there was that tragic case off Queensland a few years ago when three old blokes disappeared off a large cat in good weather and were never found.

    Presumably one fell in, one jumped in to rescue him, and while trying to haul either one or both out, the third guy lost his hold and fell in, while the cat sailed blissfully on...it's rig was still set when it was found adrift.

    Class case where a single harness and life line could have prevented tragedy.

    And/or auto-inflating life vest on the first guy, who then wouldn't have needed to be rescued, if in fact that's what happened.

    Seems highly unlike;y that all three could have had simultaneous heart attacks *and* fallen off the boat.

    So it isn't just collisions and inversions we need to be wary of!
     
  14. Corley
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    Corley epoxy coated

    Sure fatalaties occur and the most common cause is going overboard. There are far more drownings from small powerboats but then there are a lot more out there on the water in them on any given day. It's amazing how many people die from going in the water in what you would think are quite safe surroundings such as Marinas and quiet anchorages.

    Safety depends on the individual too. I was on watch while still very seasick one night on passage back from Port Lincoln to Melbourne. I must have fallen asleep and woke up in a panic fifteen minutes later to find my fellow watchmate gone out of the bridgedeck cabin where we were on watch. It was ok as it turns out he had just gone to the back of the boat for a smoke however he had no life jacket, tether or PLB if he had fallen overboard due to an unexpected event we would not have known he was gone for a quarter of an hour.

    There were three elements to the problem

    a) I was sick and exhausted and probably should not have been on watch (I didn't want to let the other guys down but should have considered myself incapacitated) perhaps the skipper should have excused me from watch duty until I recovered.
    b) My watch mate should have woken me before going out of the bridgedeck.
    c) Nobody was effectively on watch as from the position where my watch mate was seated there was not a full view around the boat or easy access to the helm.

    So elements of risk can add up quickly to a dangerous situation quickly. Needless to say lesson learned on my part and I'll not be as careless in future.
     

  15. cavalier mk2
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    cavalier mk2 Senior Member

    I'm not sure there were auto inflating lifejackets in wide use back when Rob James died. He should have been wearing something though.... How many charter sailors were them? We have rules that some view as silly but then I have more fun being thought a fool than being one.
     
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