Escape hatches

Discussion in 'Boat Design' started by Manie B, May 28, 2008.

  1. Manie B
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    Manie B Senior Member

    Gents

    one thing that i cant get my head around is the validity of escape hatches on an inverted cat

    when the damn thing is upside down
    is it not safer and or easier to try and swim out

    keep the air in the hulls
    no way will the boat sink

    i dont even like thru-hull fittings below the water line
    paranoia ? ? ?

    safety at sea = brownie points that you collect over time:D
     
  2. Trevlyns
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    Trevlyns Senior Citizen/Member

    Can't comment on escape hatches, but I know I'd NEVER have through hull fittings. I'm not busting my butt to make my hulls waterproof and then cut dirty great holes in them :p To be fair, my boat is a 24ft proa with a Yammie 5 horse outboard. Any seawater wanted on board for cooking etc can be scooped up in a bucket.

    Best!
     
  3. Knut Sand
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    Knut Sand Senior Member

    A line of c4 will get you out.....

    To swim out of an inverted boat... all those ropes..... No...

    To have (big) holes under the waterline... No....

    When we were designing FRB's they had to be rightable (2 men immersed in water shall be able to righten the boat) or self rightening. When it was tricky, we ended up with an inflatable CO2 bag on a Targa thingy...

    How big must a thing like that be to righten a boat like this...? Maybe not a CO2 bottle, need only an air pump, closed cell battery, a big bag under one hull? And a hose to the surface.

    Just a thought, will remove the issue of a hole under water or a risky bath.

    btw, If anybody is going for a patent here, I'm in! :D
     
  4. Knut Sand
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    Knut Sand Senior Member

    A drift anchor remotely operated from both hulls inside; possible..tick.
    :idea:
    will place inverted boat with the predetermined side towards the wind; possible..tick.
    :idea:
    Start airpump, release lift bag enclosure. Hull towards wind will rise above sealevel? Areas of the lower hull may come high enough above water for a hatch in the (correct side, above wl) upper area of the hull to be opened? ; possible..tick.
    :idea:
    Wind force on the sails may force/ hold the boat down, so there'll have to be some release mechanism for the sail from the inside of the hull. (Baker burst/ ejection bolts); possible..tick.
    :idea:
    Or am I under toooo heavy medication here?
     
  5. tspeer
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    tspeer Senior Member

    I've spent the night on top of an overturned trimaran in the northern Pacific that didn't have an escape hatch, so here are some of my impressions, partly based on experience and partly based on what I've read about and heard from people that have hatches.

    One of the under-appreciated aspects of an escape hatch is it's almost as important to be able to get back into a capsized boat as it is to get out!

    Unless you're singlehanding, there will undoubtedly be crew on deck in conditions conducive to capsize, and there may be crew inside. When the boat goes over, the on-deck crew will gather on the hull and the inside crew will escape. Everyone will gather on the bridgedeck to count heads and assess injuries.

    But then the attention will turn to getting stuff. Unless the ditch kit is accessible from the underside of the boat (which it should be), there will be a need to go back for the EPIRB, VHF, flares. Then you'll need to fish out the survival suits, foul weather gear, or life raft. After that, will be the need to go back for water and food. And stuff to hold the stuff you've brought outside, because there's no place to secure it. And rope or webbing to secure yourself to the boards or keel. None of that will be in the ditch kit, even if its accessible.

    Swimming in and out of the hull is more hazardous than one might think. All those sheets, halyards, and control lines hang down, making a veritable forest to be navigated. It would be easy to get tangled up in one. In cold water, you're looking at repeated immersion and increased hazard of hypothermia.

    Finally, an escape hatch provides a means of communication between those outside and inside.

    There's a great deal of flotation in the core of the structure of the boat itself. Chances are, the boat will float surprisingly high in the water. For example, a Farrier-designed trimaran will float with the decks of the amas barely submerged. The water depth on the trampoline is only ankle to calf deep. For a cruising cat, the volume in the cabin top, decks, and topsides provide flotation without depending on the trapped air.

    It's actually quite valuable to have the escape hatch vent the air trapped in the hull. Unless the air is vented, conditions inside the hull will be uninhabitable. As the hull bobs up and down in the waves, the air pressure inside fluctuates to a degree that is intolerable for extended periods.

    A properly designed escape hatch will be above the static waterline both upright and inverted. There is a risk of leakage in a seaway, of course, but that should be easily prevented or controlled.

    Aside from the escape hatch, there are some other aspects of capsize people don't appreciate.

    Unless secured by latches, all the things stored in the boat will fall out. The open companionway in conjunction with wave action is incredibly efficient at flushing every loose item out of the boat. The companionway is huge gaping hole in what is now the bottom of the boat. The waves surge in and out of the companionway, moving items to and fro. Then they reach the companionway and they're gone. The moral of the story is to provide secure storage. Add cleats and latches to lift-out lids to underseat stowage. Cupboards should have latches on the doors, etc. Even if you never capsize, these provisions can keep items secure in rough conditions.

    Battery acid and seawater is not a good combination. Batteries need to be well secured so they remain above the water when capsized. Sealed batteries require less maintenance and are safer in a capsize.

    Fuel and oil will likely be floating on the water, especially in the cockpit or wherever the engine and fuel tank are located.

    If you're going to be found, it will be through electronic means. It will be because the EPIRB broadcast your location, or you called for help on a hand-held VHF, or the radar on the search plane picked you out. The EPIRB and VHF must be accessible. It wouldn't be unreasonable to carry either or both in the pocket of someone's foul weather gear when in rough conditions.

    Finally, I have it on good authority that an escape hatch is most useful for loading groceries onboard from the dinghy! Row up, open the hatch, and hand the stores in - easy. Then you only have to deal with getting yourself from the dinghy to the boat.
     
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  6. eponodyne
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    eponodyne Senior Member

    That is damned good advice
     
  7. SheetWise
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    SheetWise All Beach -- No Water.

    It seems to me that it's simply a design issue. The door to a building is often, when locked, the most secure part of the structure.
     
  8. Knut Sand
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    Knut Sand Senior Member

    "A properly designed escape hatch will be above the static waterline both upright and inverted".

    And then you will not need any of my ideas mentioned above, way much better, simpler. :D
    I like it.

    Also the thing you mentioned about getting back in... It's quite clear, also is an issue here.

    Thanks for sharing this information. :)

    About batteries and oil; sealed batteries located in dry zone also in the inverted position, have hever thought about it like that. (have specifyed /drawn sealed batteries in boxes with gaskets and went hose.
    Oil, the boats (life boats, rescue boats) I have had the pleasure of participating in tests on: Oil leakage have never been an issue, check that engine stop funcion is ok, restart after righting. Oil leak have never been an issue, but it's clear that over a period, inverted, oil will get out. A fixed engine cover or hatch, with sound insulation which also have some capability for oil suction (what's the word? To dry up oil spillage/ dry up?) might reduce some of that problem, when inverted.
     
  9. kenJ
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    kenJ Senior Member

    Loosing Oil

    As a retired Search and Rescue helicopter pilot I can't tell you the number of times I found a small boat or life raft because of the oil slick in the water, especially at low sun angles when it is hardest to see details on the water. I'm all for the environment, but I don't think the 4 or 5 qts of oil in most marine engines are going to hurt it. Just a thought, don't want to make things too too secure and loose this possible rescue assistance.
     
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  10. Fanie
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    Fanie Fanie

    Excellent response there Tom !

    This makes me think if the cat does not have an escape hatch you have to put items that one would like to recover where you can get to them, like at the cabin door and on the floor, tied down of course. This should be above the water line when capsized.

    I was wondering if the emergency stuff could not be in a storage space in the cabin furniture. If capsized you can undo the floor emergency hatch of the cabin and all your required items should be in there. Even the instructions on how to open the emergency hatch :D
     
  11. tom28571
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    tom28571 Senior Member

    Sailors have spent extended time waiting for rescue in the hulls of capsized multihulls. Some would have certainly died of exposure without a proper access hatch. A dry place to rest multiplies the chance of survival.

    Tom Speer's thoughts add experience to good basic advice.
     
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  12. Knut Sand
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    Knut Sand Senior Member


    Well, I too consider myself partly an environmentalist, sort of at least...:D
    But I was not thinking of the environment in my proposal, I was rather considering the fact that swimming around inside an inverted pretty dark hull can be a greasy, cold job with some risk of swallowing engine oil etc. I mean the described situation is shitty enough, and if you're also to set the digestion system on "auto" that's hardly gonna improve your view on the situation... That was why I suggested engine sound insulation with some "suction" abilities. A properly designed engine cover could also help to keep the oil in the engine compartment.

    Believe me, if I had been in such a situation, I would have thrown off barrels of oil by the numbers (not even considered today's level of price), if I had believed that it could improve my chances for beeing rescued....

    This thread is getting pretty educating.;)
     
  13. Manie B
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    Manie B Senior Member

    Gents - a big thanks for the input
    very very good

    believe me i will have oil handy for a spill
    thanks kenJ:D
     
  14. Fanie
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    Fanie Fanie

    Better design the hulls to work upside down or upright never mind the oil ;)

    I'm having some emergency flashers made... lemme know if you want some.
     

  15. tspeer
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    tspeer Senior Member

    Actually, it's not necessarily all that dark inside the hull. In daytime, the luminous blue light coming in through the submerged companionway is beautiful and there would be light coming in through the portlights, too, even though they are underwater.

    In my case, I was trimming the spinnaker, ended up in the water near the hull, and the cockpit settled over me as the boat turned turtle. The fuel can for the outboard was under the cockpit seat. The airspace under the cockpit started to slowly disappear as the boat settled. As the airspace got smaller, the gasoline fumes got more pronounced. I don't believe there were any fumes in the cabin, as the companionway sill was underwater and sealed off the cockpit from the cabin.

    On a bigger boat, the tankage will be better secured and the engine more enclosed. However, there will be oily water in the bilge that can escape.

    A couple of other items I didn't mention earlier, was I was wearing a tether and self-inflating PFD. My tether was a three-hook Mustang brand. I was not very experienced at using the tether at the time, and it took me several tries to release the Gibbs hook. I also carry a Buck folding sailing knife in a sheath attached to my PFD harness. I was all but ready to get it out to cut the tether when I finally got the hook released.

    When I exited the cockpit I was under the tramp, and had to then go a short distance to clear the aft beam. I've had USAF training for getting out from under a parachute in the water, and I didn't find it to be any big deal to push myself down and walk with my hands to get out from under the tramp. It wouldn't have been any more difficult had I found myself in the middle of the tramp instead of near the cockpit.

    There's a great deal of controversy about self-inflating vs manual PFD's amongst multihull sailors. The concern is being under the tramp, not being able to breathe because the tramp is under water, and not being able to swim out because the PFD is inflated. The counter argument is there are other, more likely, situations in which one might be overboard than capsize, and for them, it's better to be self-inflating - like if you're knocked unconscious. Let's just say that now that I have a cruising tri of my own, I have inflatable PFD's on board for the crew - and they are self-inflating. And they each have a light added to them. I haven't sprung for knives, yet, but I should do so.

    Once on top of the boat, my three-hook tether proved to be very useful. Although I had abandoned it when I escaped, I was able to reach through the gap between tramp and beam and recover it. I clipped one end to my PFD. The other end went around the extended daggerboard and clipped onto the tether itself. This secured me, and left the middle hook unburdened. We hooked the ditch kit Pelican case to the hook in the center of the tether. The other guys, who ended up sitting on the hull forward of the daggerboard, hooked their tethers to the loop of mine encircling the daggerboard. Now everyone and everything was secured to the boat.

    Since then, I've gotten a lot more experience with my tether, because I use it every time I'm single-handing the F24, even if it's in drifting conditions. I don't fumble with the trigger on the Gibbs hooks like I used to. I like my three-hook tether because of the options it gives me. I normally have the center and one end clipped to my PFD and the other end to the boat. I can clip the other end to the boat before releasing the other end, ensuring that I'm never unsecured. I can also release the center hook to give me an extra -long tether that allows me to reach the ama or to step around to the other side of the mast when I've only rigged one jackline.

    I've gotten pretty used to the tether from single-handing, although I haven't used it on the new boat, yet. It can still provide surprises, though. I once made a nice single-handed approach to the gas dock, stopping just inches away, and dashed for the ama to secure the dock line. Just as I was almost to the ama, I got pulled up short by my tether, like a dog in a cartoon! The guy standing on the dock was amused, but it spoiled the whole effect of my performance.
     
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