Cruising Sailors Forum Archive

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• Thin gravity holding tank question
  • That tank will have a lot of pressure on it from the 40" of "head" pressure
    • And you will have to pump up hill from the head to the top of the tank.
      • You should pump up to a vacume breaker that is high anyway. You don't want to have the tank siphon back into the head.
        • A holding tank can't siphon into the head
      • I checked with Raritan and they said I would pump up with no problem
        • The pump is designed to pump up over 6' to the top of a vacuum breaker and then down a hose back to a holding tank.
          • I guess I'll have to keep up with with a good working joker
            • Tom, the issue isn't the toilet
              • vacuum break not necessary on output of tank
              • Yes there are simple diagrams here is my example
                • That would be perfect if space allows.
                • Good but not great
    • Not really...
      • It's the vertical height of the head (irrespective of whether it's five miles long or wide?
        • Still not quite....
      • correction...
    • The sides of the tank have to thicker or reinforced more heavily to handle the deeper tank.
      • Yes I will need to support the sides as well as the bottom
      • Out tank is made from 1/2" thick welded
    • It empties by opening the seacock and flowing into the sea
      • It will only flow out, to the extent that the bottom of the tank is below the waterline (maybe while heeling).
        • The tank will partly fill when heeling
  • I think he means that he won't pump the tank out, he'll just open a valve and it will drain into the 3 miles offshore...
    • The plan is to cruise outside the US
  • We have a gravity tank like you describe, butlarger
    • That system should work great.
  • What I suggest is...
    • I did similar, and eliminated the Y valve altogether.
      • I have a similar setup
        • Yes, except my bladder tank isn't vented.
          • Risky business...
            • Maybe you should get rid of that vent, Brian.
              • Tom, read Peggie's post farther down.
                • I did, good advice. Thanks.
        • Correction - not using Snake River gage
        • Looks like a big tank. How many gallons, Larry?
          • It's only 18 gallons
          • Here's an image
    • I also plan to plumb my sink drain to my head feed
      • You won't have a trap? Don't do that....
        • The reason for a trap in sinks in buildings is to block sewer gas
        • Nothing wrong with doing that