question regarding trawler hull

Discussion in 'Boat Design' started by kcxd, Feb 19, 2016.

  1. kcxd
    Joined: Feb 2016
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    kcxd Junior Member

    I can't handle a 8 yr old question. need help.

    why all trawlers,crabbers in EU countries looks like a bath tub? shorter, deeper, wider, while Chinese trawler are longer, shallower, narrower? with similar displacement & engine power.
     
  2. DCockey
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    DCockey Senior Member

    One reason may be the regulations governing boats used for trawling.
     
  3. kcxd
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    kcxd Junior Member

    http://www.huanghaiship.com/photo/show-227.aspx
    a typical chinese trawler looks like this. however, this one is bigger in displacement.
    with 200t displacement in mind,
    in western countries, typical dimension L20m, B7m, D4m(normally, 500KW@2500mm propeller dia), while in China, L30m, B5m, D3m.(400kW@2000mm propeller dia)

    there's no regulations governing regulate the size but need to pass safty check to obtain license.
     
  4. kcxd
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    kcxd Junior Member

    a 24m Chinese trawler would be lot smaller in beam and depth, as well as displacement and capability, engine power everything.

    another question...what the purpose for those grid along side the trawler on the hull?

    one more question...what do I do with a trawler obssessed kid...
     
  5. kcxd
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    kcxd Junior Member

  6. Tad
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    Tad Boat Designer

    Mostly the short, fat, high-sided boats are a product of length based licensing. More hull volume, higher sides and more beam, means more capability to earn money. Fishing licenses (allowable catch) are granted with a maximum vessel size attached, and these licenses have a market value, so are part of the cost of doing business. Licenses for longer (larger) boats are more valuable. So the biggest, shortest boat is seen as the most profitable.

    The "grid" on the quarters are rub strips of solid steel. This is the area where the otter boards (google otter trawl) land when the net is brought up. The boards are heavy and loose, very dangerous in a big sea.
     
  7. Tad
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    Tad Boat Designer

  8. kcxd
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    kcxd Junior Member

    thanks Tad, almost ready explain to my boy the bath tub design may have sea-keeping concerns, or hydrodynamic design for better fuel efficiency. thank you for your correction. I can think of the funny face on the other side of phone....dad, I got you!

    you are right Facebook doesn't work from here, in the name of anti-terrorist but certainly block away many useful info from our ordinary good people.

    I know a superintendents works on Chinese 40m trawler but will not bring kid onto it for visiting as safety measures aboard are really poor.
     
  9. kcxd
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    kcxd Junior Member

  10. MoePorter
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    MoePorter Junior Member

    The boats used in the Bristol Bay, Alaska sockeye gillnet fishery look like this for the same reasons Tad explained. 9.7m length - 4.6m beam - 391kw!

    No...I'm sorry but obsession with marine knowledge is life long affliction - first shows up in 8yr olds - and there is no cure, so sorry...Moe

    http://www.allamericanmarine.com/project/32-aluminum-fishing-vessel-bristol-bay-gillnetter/
     

  11. kcxd
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    kcxd Junior Member

    Thanks, Moeporter, it's very complex physic when talking about vessel hull. more vaiables than automobil. I think other than some super short fat high-sided boat, there still be a reason to have trawler hull looks more chabby...that is sea keeping.

    same displacement, deep draft fat hull vs shallow draft slender hull, should have same fuel economy at low speed.

    what I talked to the boy seems worked, people liked sedan, others like SUV, if they are at low speed, at same weight, same engine size, same tire size, fuel economy is about same, only different was at high speed or rugged terrain.
     
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