Fishing trawler problem

Discussion in 'Stability' started by mtht110, Apr 24, 2012.

  1. mtht110
    Joined: Jun 2011
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    mtht110 T. Hoque

    I have to calculate the capacity of fish hold for fishing trawler. Any one can tell me what is the density of fish. I calculate the volume but what is density of fish?:confused:
     
  2. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    1 person likes this.
  3. mtht110
    Joined: Jun 2011
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    mtht110 T. Hoque

    Thank you bro:cool:
     
  4. tunnels

    tunnels Previous Member

    Use the fish scale !!!!:idea::confused::?:
     
  5. mtht110
    Joined: Jun 2011
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    mtht110 T. Hoque

    I'm very confused. So which density I've to use for my Fish hold capacity calculation. After calculation I've to approve this calculation from Classification Society. I here is no chance to mistake.
     
  6. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    What is the fish species? How are they stored in the hold? Is the the hold one large open space or individual tanks and is there any structure obstructing storage?

    From the list in the link above........

    Whole fresh Herring in bulk - 932 kg/m3
    Whole Gutted fresh Cod in bulk - 793 kg/m3
    Whole gutted fresh Cod in layered ice - 224 kg/m3
    Frozen fillets in large blocks - 881-961 kg/m3
    Frozen fillets in consumer pack - 400 kg/m3
     
  7. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    You usually have fisheries in boxes 450x300x120 (or similar) with 15-18 kg each. Calculate the number of boxes that reasonably fit in the hold, discounting corridors, etc., and follows the load on it.
    When fish is stored semi-alive in tanks the total weight is largely unchanged from the tanks filled with water.
    Bring the fish in bulk in the hold will deteriorate dramatically fish and, therefore, in my opinion, you should rule out this possibility
     
    Last edited: Apr 27, 2012
  8. rappitysnap
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    rappitysnap New Member

    I dont know if this helps but. I run a small operation 30' boat with a max of around 4000 pounds and when i build fish holds or boxes for mackerel, mullet, snapper. I figured for every 55 gallons of volume i can hold roughly hold 400lbs in a slush. if you calculate your volume and convert it to gallons you can get it pretty close
     
  9. Submarine Tom

    Submarine Tom Previous Member

    Fish have a swim-bladder they squeeze to compress the air within allowing them negative buoyancy.
    Fish have slightly negative buoyancy.
    Call it 1.05
     
  10. TANSL
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    TANSL Senior Member

    We've all seen pictures of dead fish floating on the water surface. This suggests that a dead fish has positive buoyancy. ?????
    The ease with which a live fish moves in water suggests that its apparent weight is very similar to the volume of water displaced. And it achieves this, in fact, thanks to its swin-bladder. (Buoyancy = 0)
     
  11. hoytedow
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    hoytedow Wood Butcher

  12. midnitmike
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    midnitmike Senior Member

    Whenever I calculate fish hold capacity I've always used the density of sea water as my standard. This eliminates the need of knowing specific fish species, or how it's stored (dry, dry ice, slush ice, RSW, or blast frozen). The calculations are greatly simplified yet surprisingly accurate given the number variables one could involve.

    MM
     
  13. Submarine Tom

    Submarine Tom Previous Member

    Good post Hoyt!

    TANSL,

    The question is "what is the density of a fish".

    The answer is about 1.05

    The density of water is about 1.0 at 4 degrees celcius.

    Dead fish float because they gas up from rotting inside.

    The OP may want to consider the space between the fish went transporting, what the fish are packed in, the container they are packed in, the type of fish, the density of the water they lived in, and many other variable which are far beyond the scope of his/her question.
     
  14. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    What our friend MTHT100 needs to know is, not how much weights a fish, but the load it can carry in a cargo hold and under what conditions, the possibility of shifting of cargo, free surfaces and anything else that now I can not think.
    I totally agree with MIDNITMIKE.
    In any case I do not think it worthwhile to continue this discussion.
     

  15. Submarine Tom

    Submarine Tom Previous Member

    Sorry TANSL, that exclamation mark after your name was supposed to be a coma, my mistake, I had the cap lock on for your upper case forum name and forgot to take it off before hitting the coma botton which doubles as an exclamation key when on caps-lock.
    I wasn't trying to express anger at your post.
    If we want to read into what the OP is really wanting to know (a dangerous practice I've found) then I think a density of 1.0 should suffice and consider it water. Baffles may be a prudent feature to reduce free surface effect.
     
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