Dynamics of a cylinder water tank in a Sailboat

Discussion in 'Hydrodynamics and Aerodynamics' started by wesley Sherman, Feb 7, 2020.

  1. wesley Sherman
    Joined: Jan 2020
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    wesley Sherman Junior Member

    This seemed like a good forum to run a proposed water tank system in my sailboat.
    I have built 1 integrated water tank aboard my sailboat, food grade epoxy baffles ect.
    My other idea which comes from an water tank I made when doing a 4x4 trek on the continental divide. I had a water tank with Baffle balls in it. It stopped the sloshing from push the truck around.
    So my idea is to buy 10' of 8" x 2 pvc pipe. Caps on the end and fittings needed to pipe to foot pump for sinks, I would coat the inside with food grade epoxy to avoid the too much plastic taste. In order to stop the sloshing movement in tank I would put 8" food grade baffle balls inside 12 total each side, it would displace a combined total of 1 gallon per tank and would weigh 6 lbs per tank. This would be removable so when I am not on a super long voyage I can have the space. They would be on either side of the bilge along the full keel.

    I am just wondering if there is anything I am not considering.. each cylinder with pipe weight included would be 221.25lbs each. 442.5 lbs. Boat is Alberg 30. Again this would only be

    Thank you for any remarks or ideas, much appreciated.
     
    Last edited: Feb 8, 2020
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Each pipe will hold approx 25 gallons, so that is 50 extra gallons of water - sounds like a neat way of getting extra capacity.
    But each baffle ball within will be one gallon, so if there are 12 you will only have 13 gallons of water in each pipe......
    Would it be feasible to introduce 'kinks' in the pipes to act as baffles (of sorts) instead?
     
  3. wesley Sherman
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    wesley Sherman Junior Member

    I corrected the above post.. 12 baffle balls combined would displace a total of 1 gallon of water per tank! So i would still end up with 25 gallons of water approx. So this would give me a total of 50 gallons, I like this idea as it would allow me not to use all my space all the time, I would also connect line between with shut off valves to occasionally balance the tanks.
     
  4. fallguy
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    fallguy Senior Member

    The surge balls displace a gallon total.

    I think removing them is silly.

    why do you want a cylindrical tank?
     
  5. bajansailor
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    bajansailor Marine Surveyor

    I must be missing something here.
    The volume of a sphere / ball is 3.142 x R x R x R x 4/3.
    If R = 4" for an 8" diameter sphere (re a surge ball), then the volume of the sphere is approx 4 litres or one gallon.
     
  6. philSweet
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    philSweet Senior Member

  7. wesley Sherman
    Joined: Jan 2020
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    wesley Sherman Junior Member

    Baffle Balls are not solid sphere, here is a link to what they are. Baffle Ball | Parts & Accessories | Enduraplas https://www.enduraplas.com/products/baffle-ball/
    these tanks would ride along side my full keel bilge inside the settees from head bulkhead to lazaret bulkhead. And still leave alot of room for storage, I ll have plenty of water tank storage when needed for very long cruises. I don't like to skimp on water needs much. I feel not having large integrated tanks in the bow is to my benefit. And having the amid ships tanks low and closer to the cg makes more sense.
     
  8. bajansailor
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    bajansailor Marine Surveyor

  9. fallguy
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    fallguy Senior Member

    I would build the balls to stay in. Glue the caps on each end.

    You might/will need an inspection port if you ever get boarded, so I would add a hub. The balls may hang on the hub so install balls each side. A 4" hub would probably be available. Personally, I would make it so the balls cannot pass the middle and use a couple fewer, or you could also install two permanent baffles in the hub middle and skip the balls. A permanent baffle would just have like a one inch open on the bottom on one side and the other one on the other side. How to bond them...not certain. Cut off some pipe and screw some plate onto it and insert it into the hub?

    I would never make the ends removable and I would pressure test the tanks to 3 pounds for 24 hours.
     
  10. wesley Sherman
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    wesley Sherman Junior Member

    There is something ad not thought of .. Inspection at ports. That would be a significant need. Thank you
     
    fallguy likes this.

  11. fallguy
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    fallguy Senior Member

    Permanent baffles like I suggest might ruffle some feathers on inspection...
     
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