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Winterizing water tank... vodka or pink stuff?

Discussion in 'Cruising Sailors' started by genec, Oct 11, 2018. Add this thread to a FAQ

  1. uncledom


    Joined Jun 11, 2011
    1,175 posts, 270 likes
    Hunter 41
    US Lewes
    @Captain Larry-DH , I too leave all the pump lines disconnected, sorry I didn't describe the whole process in detail. I have a dock water fitting on the stern that accepts city water pressure right to the water manifold. I'm pretty sure city water pressure can be near double the 60 PSI of air I put into the system and is usually at least 80 PSI so I'm pretty comfortable with the pressure I use although you are right that it well exceeds the pump pressure. Once you open any faucet there is an instant drop in the pressure on the system. At any rate it's been working fine for me with no plumbing issues but if anyone is nervous about it most compressors have an output regulator that is easily adjusted.

  2. Gunni


    Joined Mar 16, 2010
    5,943 posts, 1,489 likes
    Beneteau 411 Oceanis
    US Annapolis
    Adapt a wet shop-vac to suck water out of your water supply line from the tank.

    In general a shop vac works better than a compressor - shop vacs move lots more CFM.

    Parsons likes this.
  3. dlochner


    Joined Jan 11, 2014
    3,914 posts, 1,862 likes
    Sabre 362
    113 US Fair Haven, NY
    I'm with Peggy on this. A tank that is below waterline and in contact with the hull or near the hull will only become as cold as the water that surrounds the hull. While some ice might form on the surface of the water in the tank, this is not ice that will cause much if any damage. It takes a long time at cold temperatures to freeze a large mass of water.

    There are several factors that come into play. The smaller the temperature differential between two things the slower the heat transfer will be, it will take longer for 34* water to drop 2* than it will take 45* water to drop 2* given the same environmental temperature. To lower the temperature of 1 gram of water only 1 calorie of heat needs to be removed, to freeze 1 gram of water 80 calories of heat must be removed. A lot of energy must be removed in order to freeze water.

    Water tanks tend to sit in pretty well protected areas with out much air movement. This makes for rather inefficient heat transfer from the water tank to the air around it. Polyethylene, like most plastics, does not transfer heat efficiently and stagnant air is also a good insulator. These all contribute to preventing water in the tank from freezing.

    If there is only a small amount of water in the tank, say a gallon or so, then it might freeze, but there is plenty of room in the tank for the ice to expand. The place that small amount of ice might be problematic is the tank outlet.

  4. T Dunn

    T Dunn

    Joined May 23, 2018
    10 posts, 9 likes
    Allied Princess
    US Southwest Harbor
    Although I grew up in Western Washington, I now live on the coast of Maine where is does get a bit fresh in the winter and we do winterize our boats. Here is my procedure.

    1. Drain water heater. Disconnect input and output lines and connect them together to bypass the heater.
    2. Drain the water tank by pumping it dry into the sinks.
    3. Put water pump intake hose into a gallon of propylene glycol antifreeze (not the stuff that contains alcohol) and pump antifreeze through the lines to ALL the faucets until they run pink. One gallon is generally enough for my boat. After that I run the pump dry to get rid of as much antifreeze as possible.
    4. Winterize the head by putting the head intake hose in a gallon of propylene glycol antifreeze and pumping the entire gallon through the head. On my boat this is easy because my head intake is plumbed to the sink drain so I just pour the antifreeze into the sink and pump it through the head.

    Here is a short video I made two weeks ago of the process -

  5. Peggie Hall HeadMistress

    Peggie Hall HeadMistress

    Joined Dec 2, 1997
    7,319 posts, 818 likes
    - -
    US LIttle Rock
    Once again you need to read what I write more carefully. I didn't say that water drains back to the tank, I said it drains to the lowest level in the plumbing, almost all of which will be below the waterline.

    "If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

  6. Davidasailor26


    Joined May 17, 2004
    1,789 posts, 476 likes
    Beneteau Oceanis 37 LE
    US Havre de Grace

    Sorry, but not in my boat. If I turn off my pump its internal check valves will prevent water from flowing backwards. This means all of the plumbing between the pump and the faucets are still filled with water. If I open the faucets then the excess pressure will run out, but the water at atmospheric pressure will still be in the lines.

    Maybe if you run the pump dry there will be enough air in the lines that the residual water will run to the low spots. I wouldn't trust that to be adequate in my climate but maybe some in warmer climates could.

    Last edited: Oct 12, 2018
  7. Captain Larry-DH

    Captain Larry-DH

    Joined Jun 14, 2010
    797 posts, 439 likes
    Quorning Dragonfly 1200
    US home
    I'll overlook the "six year old" comment, and I'm sorry to be like a dog with a bone; but all it takes is one low point and cracked fitting to cause problems.

  8. kappykaplan


    Joined May 1, 2011
    1,021 posts, 215 likes
    Pearson 37
    US Lusby MD
    That's part of Peggie's signature block . . .

    Parsons likes this.
  9. genec


    Joined Dec 30, 2010
    188 posts, 57 likes
    Pacific Seacraft Orion27
    US HP: San Diego, M: Anacortes
    It's beginning to sound like what I should do is what I had done, "accidentally," in years past.

    In years past the water tank had a bad cover, so I never left it full... none of the water lines froze and the boat was fine.

    I was concerned this year as the fresh water tank is full, as I have repaired the cover...

    Sounds like I should just pump the tank dry and leave the valves open and call it a day. My water system is not complicated... there are no check valves or manifolds in it. I do have a water heater... draining that sounds like a good idea.

    But overall, I am thinking... keep it simple.

    dlochner and Gunni like this.
  10. thinwater


    Joined Mar 26, 2011
    2,360 posts, 587 likes
    Corsair F-24 MK I
    US Deale, MD
    Most years we only get a skin of ice and I sail all year. Some years none at all.


    This past winter was exceptional, and we got a good 4 inches at the peak. At least one sailor I know of left his water tank partly full and virtually destroyed the boat, considering the tank was built-in. All of the pumps and some of the plumbing were destroyed.

    Yes, generally the "in water" logic holds, but if you can get ice on the water, it is a roll of the dice. Cabin temperatures can easily drop below freezing for a day, and that will damage faucets and smaller things. I'd be more relaxed with it winterized, just in case. It's nice not to worry.

    Justin_NSA likes this.
  11. Ken Cross

    Ken Cross

    Joined Oct 24, 2010
    1,984 posts, 330 likes
    Hunter 30
    US Everett, WA
    I've always left some heat on (heater set to 750 watts) and the thermostat set to about 50 f. Sure the power could go off, but then it's usually above freezing. I open up inside cabinets, the head door, the engine cover, etc.
    Our water in the Everett Marina is brackish and usually freezes but not a hard freeze. No problem so far.


  12. thinwater


    Joined Mar 26, 2011
    2,360 posts, 587 likes
    Corsair F-24 MK I
    US Deale, MD
    A portable heater? Unattended?

    If this is the case, marinas around here expressly forbid that. Too many boat fires.

    The other problem with relying on heat is that the probability of loosing power during an ice storm, followed by a cold blast, is material. A GFI could pop. Winterization should be passive.

    Parsons and Captain Larry-DH like this.
  13. Captain Larry-DH

    Captain Larry-DH

    Joined Jun 14, 2010
    797 posts, 439 likes
    Quorning Dragonfly 1200
    US home
    Any marina I’ve used for winter storage would unplug extension cords that are for an unattended boat.

    Last edited: Oct 13, 2018
  14. JamesG161


    Joined Feb 14, 2014
    3,767 posts, 1,423 likes
    Hunter 430
    US Waveland, MS
    If you water tank is Aluminum, then cheap Vodka.
    Vodka will dissolve any Aluminum Chloride crystals and clean your water tank.

    You may use "Ever Clear" for a stronger Alcohol.

  15. Jeff Gray

    Jeff Gray

    Joined Nov 26, 2017
    64 posts, 8 likes
    Hunter 260
    US Mille Lacs
    Who says he’s gonna waste it? Come next season, the party can flow straight from the tap! Lol!

  16. thinwater


    Joined Mar 26, 2011
    2,360 posts, 587 likes
    Corsair F-24 MK I
    US Deale, MD
    a. Vodka clean the tank by dissolving aluminum. It is actually far more corrosive than glycol or water. I did the side-by-side testing using standard methodology. [​IMG]
    b. After the vodka ferments (which can happen to any under strength AF glycol or alcohol), it will be nastier than the half-empty bottle of Boones Farm under your back seat. This is the nasty taste people observe in their systems, not a "chemical" taste. Vodka is ONLY antiseptic if maintained about 25% ethanol. You won't need a few bottles, you will need 50/50 vodka/water, which will cost 2-3 times more than AF, even if you shop the bottom shelf.

    c. Alcohol is rough on some of the plastics and elastomers. I would not put it in my boat in any form (other than the liquor cabinet).

    d. Without dye, it will be hard to tell when the vodka is coming out the other end.

    The Vodka thing is a tired myth. It makes no sense on any level (corrosion, cost, taste). Can't we bury it?

    Parsons, Captain Larry-DH and plenny7 like this.
  17. Tally Ho

    Tally Ho

    Joined Jan 7, 2011
    1,410 posts, 311 likes
    Oday 322
    US East Chicago, IN
    I will be hauling out on October 27 (I like to be last ones out, first ones in).

    On my O’Day 322 with 2) 30 gallon water tanks and a water heater, I like to:
    1) isolate water heater with bypass valves. I drain the water heater and leave it alone.
    2) run the water tanks empty with the water pump. Then disconnect the water line from each tank, add a short piece of water line and put it in a gallon of pink stuff. Turn on the water pump and open both galley and head sink faucets and run a gallon through. Then move to other water tank and repeat. Open both hot and cold water faucets in galley and head sinks. Run pink stuff through the system.
    3) run a gallon of pink stuff through the toilet water strainer, through toilet pump, toilet and into holding tank.
    4) run 2 gallons of pink stuff through the engine freshwater strainer, through engine and out exhaust.

    These steps have kept my boat safe and sound through some damn cold winters in Chicago area winters.

    And I don’t have antifreeze in my water tanks or water heater come spring time!


  18. Rich Stidger

    Rich Stidger

    Joined Feb 10, 2004
    2,921 posts, 335 likes
    Hunter 40.5
    US 1997 h40.5 Bristol, RI
    Skip the vodka. Skip the pink stuff. Blow out all the lines and pump with your dinghy air pump or compressor. Blow any water in the lines back into the empty water tanks. Any residual water will not do any harm because it will not be in a place that can build pressure. I have been doing this for 30+ years. If you don't believe, and are afraid of a low spot that might freeze, the fill with the pink stuff. But even if you have a low spot, and if the entire line is not completely filled then a freeze will just push up the line and do no harm. Blowing out the lines will not result in a completely filled line. As always, YMMV.

    Captain Larry-DH likes this.
  19. dlochner


    Joined Jan 11, 2014
    3,914 posts, 1,862 likes
    Sabre 362
    113 US Fair Haven, NY
    @Rich Stidger I mostly agree with you, however, a little residual water in the pump mechanism or the faucet innards can cause some damage, especially in areas subjected to long periods of deep freezes, like upstate NY.

    Short mild freeze-thaw cycles may actually be helpful. As water freezes it gives off heat that heat causes some water to vaporize reducing the water volume in a well ventilated area. Now, I will admit that I have no empirical data to support this specific claim, just 45 years of casually observed data.

  20. Rich Stidger

    Rich Stidger

    Joined Feb 10, 2004
    2,921 posts, 335 likes
    Hunter 40.5
    US 1997 h40.5 Bristol, RI
    True, but I did say that you blow out the lines and the pump, and since you blow all of the water out the faucets, there should not be any significant water left in the faucets.

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