Unsinkable boats realy?

Discussion in 'Boat Design' started by tom kane, Oct 12, 2014.

  1. tom kane
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    tom kane Senior Member

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  2. Rurudyne
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    Rurudyne Senior Member

    Even if a boat was in and of itself unsinkable the odds are the crews wouldn't be.
     
  3. rwatson
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    rwatson Senior Member

    There are plenty of unsinkable boats - you can see the little pieces drift by in the great plastic islands in the Pacific ? :)

    When you factor in the extra cost, loss of room and extra weight, suddenly unsinkable seems less important to the average cash-strapped boatbuilder :-(
     
  4. DCockey
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    DCockey Senior Member

  5. DCockey
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    DCockey Senior Member

    Most powerboats under 20 feet overall length sold in the US are required to have positive floatation.

    My understanding is overall most deaths while boating are not caused by a boat sinking.
     
  6. rwatson
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    rwatson Senior Member

    yes, good points.

    Also, don't forget that 'unsinkable' does not necessarily mean 'survivable' for the two week period prescribed in the Proboat paper.

    In really poor conditions, having an unsinkable boat is just for making the bodies easier to find.
     
  7. Rurudyne
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    Rurudyne Senior Member

    That bubble was probably unsinkable....
     
  8. Steve W
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    Steve W Senior Member

    I believe all Macgregor boats were unsinkable, my Mac 36 cat was not only unsinkable, not just survivable but in fact in its most "sunk" state you could continue sailing, not much more than an inconvenience really. It had so much foam floatation that it had a plug in each hull you could remove to allow the power of the floatation to raise and drain it until it was only maybe, thigh deep. I know the Mac 65 also had tis floatation. My sons 24ft uldb which I designed and built 27 years ago has full floatation, also habitable. We have never needed it but it is very reassuring to have.

    Steve.
     
  9. tom kane
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    tom kane Senior Member

    That is what I would call unsinkable..a boat that can still be operated when full of water. That is why I loved my classic ply boat.
     
  10. bpw
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    bpw Senior Member

    Its a more money weight, and less space to prepare for a very unlikely event that doesn't kill many people. There is a good argument for spending the money on a life-raft instead since a life-raft can save you in a fire as well.

    A jet-ski won't sink but it is still by far the most dangerous type of boat.
     
  11. PAR
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    PAR Yacht Designer/Builder

    Tom your description of unsinkable isn't realistic, let alone practical from a marketing point of view. Having a fully swamped boat still operational, would add exponentially to it's cost, for no real useful purpose. Why would you think this is a reasonable or practical operational requirement on a pleasure craft? Making a swamped boat operational, presents huge problems with free surface affects, it's stability curve and any reasonable or practical aspect of safety, for a well soaked crew, likely putting them in further danger, as they attempt to motor this wallowing monolith to shore.

    As has been noted, small production sold in the USA have to meet specific floatation requirements. Once you get much over a ton and a half, making this requirement becomes less and less practical, so subdivision of the enclosed volume is the logical answer. Titanic couldn't have been made unsinkable and still had room for passengers and equipment.

    Engineering is about accepting risk and when placing humans in "unnatural" environments, such as 35,000' in the air or father from shore then you can swim back to, the margins and redundancies go up, but some risk has to be accepted. It's the nature of the beast and planning for every eventuality, particularly the most remote ones, usually isn't practical.

    The space shuttle ferried 355 up into space and as you'd imagine a very high level of margin was engineered into the equipment and processes, yet nearly 4% died. Considering the complications of these types of engineering escapades, not bad really, though compared to yachts in the USA appalling.
     
  12. whitepointer23

    whitepointer23 Previous Member

    it is law in Australia. all boats are manufactured with positive buoyancy. they must float even when full of water. I am pretty sure it has to be foam to. not just air tanks. this law has been in for a few years now. even home builders may be required to prove they have it to obtain a h I n number. I think it is a good thing to. that and epirbs are probably 2 of the best things I know of for fishing safely offshore.
     
  13. whitepointer23

    whitepointer23 Previous Member

    I would rather wait in a flooded boat for rescue than float around in my life jacket with all the shark attacks happening around our coast at the moment. that poor young surfer had both arms bitten off last week.
     
  14. bajansailor
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    bajansailor Marine Surveyor


  15. Emerson White
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    Emerson White Junior Member

    Talk about mitigating for risks that are virtually non-existent. Millions of people swim in the ocean every day, and on average shark attacks kill one person every 3 months. You are more likely to be injured by a dog on the docks than a shark by orders of magnitude.
     
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