V Berth Water Tank

[SV Someday Came]

My water tank is in the V berth. As you can see, the seal which held the plywood (which is rotten) is terrible. When I bought the boat, I did not even think to look underneath the V berth cushions! Anyways, I have cut a piece of plastic to be the lid on the tank. The problem is that I cannot a glue or sealant that can hold the plastic to the fiber glass. The plastic is the same material used in those white plastic chopping boards. To make matters worse, some of the sailors at the marina are telling me that I need to make the lid removable for inspection. I don't see why. No one has inspected the tank for close to 23 years now. Nonetheless, I have sanded the interior of the tank and have painted it with Interlux white polyurethane. But I need a solution as to how to seal the tank. The previous idiots used silicone sealer and many, many screws. Naturally, the seal leaked like a sieve. I have drilled out all the screw holes, filled each with epoxy, and sanded the lip (i don't have pictures of that part of the project). So.... how to seal the tank? Any suggestions?

Thanks

Michael

[Alan Wheeler]

What a mighty strange place to put a water tank. Personaly, I would not be keeping the tank there at all. That is a lot of weight waay forward and up high. I would seriously look at placing a tank down in the bilge somewhere.
But...if you really have to keep it there, then I suggest you get rid of the lid you have, and make a new lid from Ply glassed over, then you can seal or glue the lid down. As you have found, you will not stick to that nylon material.
Or....if you really want to keep the top you have, you make a seal around the top about 1/4" thick and then screw the top down onto the seal.

[Ex-Calif]

Looks like a jacuzzi or an unmade waterbed. Some random thoughts...

1/ How much water is that? It looks unbaffled. Before you close it up you should consider if you want this much unbaffled water up front.

2/ I am not sure I would have painted the inside of the tank. Are you going to be drinking from it? What happens when the paint peels.

3/ I'm with wheels. You'll want to make a fiberglass top. Preferably with a 12" diameter inspection cover that you can remove.

We have about a 10 gallon tank in the same spot as yours but it is simply a square fiberglass tank with about an 8 inch port on top.

[Steve Kidson]

I am in the process of a very similar project, and my water tank is under the aft section of the V berth.

PO had constructed water tank under V berth - not full height, but using inside of hull as tank side, plywood "bulkheads" to form front and back as well as top of tank.

I discovered after having water in tank for a month or so, water quality and colour deteriorated rapidly causing me to investigate.

After opening inspection port, found much YUK YUK YUK inside.

Have removed top of tank, and in process of reomving loose and flaking previous lining prior to sealing whole lot with several coats of epoxy resin. A new top is being fabricated, in 3 pieces - middle one removable for inspection/cleaning as necessary. All will be epoxy coated, with the outside 2 pieces glassed in, the middle on removable for inspection/cleaning.

I too was initially concerned with the locatin of tank, but in my case have fuel tanks and hot water tank, with a combined capacity similar, under cockpit which should balance out.

Fair winds

Steve

[bottleinamessage]

What about putting one ore even two bladders in it?

[Duckonfidelis]

I had to replace three aluminium water tanks due to weld corrosion. I opted to form integral fiberglass tanks. My input is to be careful with the products inside the tank as suggested earlier. After my own research I discovered a vinyl-ester resin called derakane that has a process associated with it that purports to meet FDA approval specs for food contact. I also discovered there are a lot of people in the business that proceed on rumor about what is and isn't safe. If that tank is formed to the hull (rather than floating) expect that it will strain along with the rest of the hull in a seaway. This mean you will need a flexible mating surface such as seems to have been provided previously, or you need to form a load bearing top that has a very strong bond (such as screwed and bonded). I agree with a previous input that baffles need to be considered.

Bladders are rather expensive, but seem like a great solution!

Good luck.

[stevemac00]

To original question. You need to prep the plastic for sealing. You can do this by a flaming torch or Dow Corning 1205 Prime coat after sanding the surface. Be sure to use FDA approved sealant scuh as Dow Corning 999A sealant.

[Reality Check]

Just an insight... after recently (past 4 months) evaluating dozens of boats in the Carib by in water inspections and probably hundreds of paper reviews... more than 90% of the under 45 foot boats I looked at have a forward V-birth water tank of 30 to 50 gallon capacity and a smaller one aft where the fuel tank and generally all batteries are also located. While not at all Optimum for Blue Water boats, This appears now to be "Standard" practice when under 45 footers carry near 80 gallons of water which is standard for charter boats. These are NOT what would be considered blue water cruisers by most of us... they are more coastal/ light blue cruisers. The only baffles I have seen were no more than a couple of ridges possibly 1/4 of the depth of the tank and around the inspection ports... not much anti slosh but again these are not the first choice for circumnavigation boats or a boat intended to be used in heavy weather situations but use restricted by charter company rules in generally more hospitable sailing areas such as the Carib and Med. AND I KNOW both can have bad weather... but they are not intended for that service and if you own one you have to take that into consideration in your cruising plans and have a plan B ready to implement when faced with such situations which a quick pump out would be one possibility.. we do that in some similar circumstances in aircraft and fuel is far more expensive.

I would consider the bladder idea with multi pumps/ valves then a total re-glass of the tank with multi lid idea as above. I don't actually drink my boat tank water except when filtered and used to make coffee or cook with. We use it up in showers and general cleaning and some cooking when filtered... just don't care for the idea of what may be in it and most always have a chemical or plastic smell. Our water tanks are heavy plastic with good size inspection access holes and appear to be seam welded two piece units bottom and top type. For drinking we carry a supply of 2.5 gal and 1 gallon bottles... but generally find beer is the beverage of choice or something possibly a bit stronger which are not carried in the water tanks.....MMmmm draft beer in the water tanks???? gonna have to think about that one!!! Foam may be a problem but then again....

[sluissa]

if it were me, I'd just use that area to store some 1 to 5 gallon jugs. Or re-arrange my storage to put other stuff up there and find somewhere else for the jugs. Of course, I'm almost completely against built in water tanks. Small one or 5 gallon jugs keeps your water separated and even if some of it gets contaminated by something, it doesn't get to most of it.

[Paul Elliott]

My "blue-water" Pacific Seacraft 44 has one water tank at the bow, under the v-berth. On passage, I usually keep it empty, or empty it first, and use the midships and aft tanks.

While the weight of a full tank up forward is unfortunate, a well-positioned tank near the waterline will act as a small watertight crash compartment, that may be of benefit on some head-on collisions with floaring debris. I couldn't say how likely it would be to actually help should I run into something.

[SV Someday Came]

I appreciate the replies... I have a bad intuitive feeling about 600 pounds of moveable inertia at the bow of a sailboat. For right now, I am going to leave this project be. Maybe I will simply carry 1 gallon containers there. I am going to calculate the space I have in the bilge in the Willard. If I built a teak grate a third of the way up from the top of the keel and put some bladders there, I could keep a good portion of my water midship. Thanks again. You all have given me alot to think about!