Plywood water tanks?

Discussion in 'Wooden Boat Building and Restoration' started by Capt. Mike, Oct 11, 2006.

  1. Capt. Mike
    Joined: Feb 2006
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 30
    Location: St. Augustine, FL / Bahamas

    Capt. Mike Junior Member

    The stainless steel fresh water tanks on our CT42 sailboat have rusted through. Cost is a factor in replacing them. What are the opinions regarding building the replacement tanks out of encapsulated marine grade plywood? I would first use CPS to protect as well as possible before building a thick coat of RAKA epoxy. Each part would be encapsulated before assembling the tank.

    Thanks,
    Capt. Mike
     
  2. Richard Hillsid
    Joined: Mar 2006
    Posts: 117
    Likes: 4, Points: 0, Legacy Rep: 19
    Location: Scandinavia

    Richard Hillsid Senior Member

    How much are they asking for new stainless tanks?
     
  3. Capt. Mike
    Joined: Feb 2006
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 30
    Location: St. Augustine, FL / Bahamas

    Capt. Mike Junior Member

    I have not checked the price of stainless tanks, but I have checked the price for plastic ones. The pair of plastic tanks is about $500. I believe stainless tanks would be custom fabricated and more expensive. The plastic tanks come in a variety of shapes, but none are the same. Therefore to get the plastic tanks to fit the available space I would have to give up some storage capacity. If I build the tanks out of plywood, I can make them the same shape and have the same capacity.

    Capt. Mike
     
  4. lewisboats
    Joined: Oct 2002
    Posts: 2,329
    Likes: 129, Points: 0, Legacy Rep: 1603
    Location: Iowa

    lewisboats Obsessed Member

    You would have to build them heavy as they will have to contain quite a weight of water (62.4 lbs/cu ft or about 8 gals), even using CPES you will only penetrate the depth of the first layer of wood, the core plys won't have any plastic in them. You will need to put more than one coat of epoxy on the plywood and I would recommend a layer or two of glass too. Your tanks will be heavy compared to SS or Plastic...no 1/4" here. I would say 1/2"-3/4" plus some bracing too, depending on the size of the tanks.

    But that is just my opinion

    Steve
     
  5. timgoz
    Joined: Jul 2006
    Posts: 1,079
    Likes: 32, Points: 48, Legacy Rep: 277
    Location: SW PA USA

    timgoz Senior Member

    Mild steel tanks, epoxy coated (inside & out) would be effective & inexpensive. No strength issues would arise with such tanks if baffeled and built properly.

    They would also be very repairable.

    Take care.

    TGoz
     
  6. D'ARTOIS
    Joined: Nov 2004
    Posts: 1,068
    Likes: 18, Points: 0, Legacy Rep: 321
    Location: The Netherlands

    D'ARTOIS Senior Member

    Yes, that is a very good option. Make sure that the coating for the inside is chemical resistant as drinking water is mostly chlorinated.
     
  7. hansp77
    Joined: Mar 2006
    Posts: 690
    Likes: 34, Points: 0, Legacy Rep: 200
    Location: Melbourne Australia

    hansp77

    Ever the cheap scavenger/salvager...
    I have a few thoughts and questions.

    Try some of your local metal salvagers/reclyclers. Sitting in their yard may just be the exact tank (or something easily altered to) that you are after, and could be very very cheap.

    Aside from that, another thought occured.
    One afternoon I was working on my boat in the yards and thought that I needed some light stainless brackets. We went to the hardware store open and they only had galvanised.
    On the way back, the suburb I was in was having hard rubbish collection, so I stopped and picked up a nice stainless kitchen sink (these things are ALWAYS getting thrown out like this)
    With my grinder I cut off some strips and panels to make into brackets. (I ended up changing plan and not using them though)

    If the size was anything like appropriate, couldn't one just cut out two sinks, and seal/rivet/weld them upside down on top on one another? a simple plumbing attachment on the bottom would seal it (and allow for easy draining) and the plug hole on the top would be ready made to screw piping onto.
    I am not sure if it is the right stainless for a water tank,
    or if DIY stick welding would produce a sufficient weld.

    Shoot away...

    Hans.
     
  8. LP
    Joined: Jul 2005
    Posts: 1,414
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    Didn't they use to solder copper sheet into tanks?
     
  9. Tim B
    Joined: Jan 2003
    Posts: 1,438
    Likes: 59, Points: 0, Legacy Rep: 841
    Location: Southern England

    Tim B Senior Member

    The Gougeon brothers have built plywood water tanks in the past, with great sucess. I suggest you use thier book on boat construction as a starting point.

    Tim B.
     
  10. stevel
    Joined: Aug 2004
    Posts: 118
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Ventura, CA

    stevel Lost at sea

    They work well

    My dad made the freshwater, greywater, and blackwater tanks for his bus conversion out of cheap ply, and they were still leak free and rot free when I sold off his bus 17 years later. I'm not sure if they are your best option weight-wise, but if you need inexpensive custom tanks, they are a workable option. He glassed his inside, and then painted the inside of the freshwater tank with an epoxy to avoid the taste that resin puts into the water. I can't remember if he glassed the outside, or just resined it.
     
  11. Ari
    Joined: Jan 2006
    Posts: 421
    Likes: 15, Points: 0, Legacy Rep: 94
    Location: Port Dickson, Malaysia

    Ari Patience s/o Genius

    Plywood water tank.

    How many liters is the tank size? I had seen this kind of construction before. The tank do last very long if built properly but the weight.if it is thick.. very heavy. The one that I saw is for inter island fresh water supply boat, 50 tonne capacity. Normally for small size, about 300 litres tank I used HDPE -plastic tank. If you have Japanese koi fish pond liner, that also can be used to line your plywood tank. Very long lasting this liner and doesn't leech out hazardous chemicals into the water.
     
  12. Verytricky
    Joined: Oct 2005
    Posts: 248
    Likes: 17, Points: 0, Legacy Rep: 400
    Location: London

    Verytricky Large Member

    Hi,

    Some cheap scates in the marine fish world build plywood tanks for their fish, to avoid the costs involved with the very large glass tanks. Look at a fish website like reefs.org or garf.com for plans.

    These tanks are up to 500 gals, and keep delicate corals and fish, so will store drinking water..
     
  13. Capt. Mike
    Joined: Feb 2006
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 30
    Location: St. Augustine, FL / Bahamas

    Capt. Mike Junior Member

    Thanks for all the replies. The capacity of the water tanks I will replace is about 60 gallons each so I don't think they will be too heavy. I built diesel fuel tanks with plywood several years ago. Before doing so I wrote to The Gougeon brothers to see if it was practical. They sent me a 10 page paper about building tanks of plywood. Their recommendation is to apply seven coats of epoxy to the interior and to use a little less hardener than normal to be sure all of the hardener is consumed to avoid having the coating be pourous. I tabbed all the seams and coated the interior per the paper and the tanks have worked well. I was wondering if anyone had used a similar method for fresh water tanks and if there is any impact on the taste or quality of the water. By the way the diesel tanks are still in service and have no problems.

    Mike
     
  14. Ari
    Joined: Jan 2006
    Posts: 421
    Likes: 15, Points: 0, Legacy Rep: 94
    Location: Port Dickson, Malaysia

    Ari Patience s/o Genius

    Fiber glass and epoxy water tank

    My house fresh water tank are made of fiberglass and epoxy resin, it had lasted 10 years before started to leak at high stress point area.I cannot confirm the quality of water since it is not tested but on the the smell,the water is odorless. Our housing board rules doesn't allowed water supply for the kitchen to be routed to any storage tank. It must come from a direct line from the main supply pipe.
     

  15. Verytricky
    Joined: Oct 2005
    Posts: 248
    Likes: 17, Points: 0, Legacy Rep: 400
    Location: London

    Verytricky Large Member

    Really - people are keeping corals in these tanks, and corals die if you look at them funny. So the tanks have to be perfect.
     
Loading...
Similar Threads
  1. Head2wind
    Replies:
    21
    Views:
    10,176
  2. NorthLakeFisher
    Replies:
    9
    Views:
    434
  3. AwJees
    Replies:
    1
    Views:
    445
  4. sdowney717
    Replies:
    4
    Views:
    732
  5. Sunburned One
    Replies:
    38
    Views:
    2,828
  6. sdowney717
    Replies:
    30
    Views:
    1,932
  7. Travis Grauel
    Replies:
    26
    Views:
    3,877
  8. Paul D
    Replies:
    13
    Views:
    2,606
  9. Floatything
    Replies:
    0
    Views:
    1,701
  10. juan manuel luna
    Replies:
    21
    Views:
    2,986
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.