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Old 18-05-2012, 13:06   #16
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Re: Building Water Tanks

I will be building a set as soon as the shop quites down.. begining of the season and everyone wants canvas... I'll be posting a start to finish when I do..
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Old 18-05-2012, 13:58   #17
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Re: Building Water Tanks

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I will be building a set as soon as the shop quites down.. begining of the season and everyone wants canvas... I'll be posting a start to finish when I do..
You may be able to find some useful information at the tek tanks site. I think my first project will be a fuel tank and there is some very helpful design guidance there, with specs on fittings, etc.
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Old 18-05-2012, 14:09   #18
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Re: Building Water Tanks

There are quite a number of companies that make polyethylene tanks of all different sizes. There are a number of them that can make you a custom sized tank as well. They can be found by doing a Google search. I recently went through this in looking for a new potable water tank. It had to be fit into an odd shaped space against the hull. Almost nothing on a boat is square is it?..even stuff that is supposed to be square.

I don't know if it is worth trying to make one for yourself, especially when there are companies who have already made thousands of custom tanks and guarantee their work. If it does not work then you can send it back which is more than can be said if you try to do it yourself.

No glue or epoxy is going to hold together polyethylene or polypropylene, the material is just too slippery plus you will never get a chemical bond, only a poor physical bond. It has to be melted together so you get an excellent chemical bond. Polyethylene and polypropylene is very resistant to almost all chemicals that would weaken it, melt it or dissolve it. Being very inert, it also will not leech chemicals into your potable water. We use polyethylene sample containers on the research vessel for holding samples that are sometimes measured into the parts per trillion....they are that inert.
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Old 19-05-2012, 02:07   #19
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Re: Building Water Tanks

Yes I agree with David , glue will not do but the heat gun and filler rod is quite easy to use. I used to weld plastics when I was an apprentice.

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Old 19-05-2012, 02:19   #20
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Re: Building Water Tanks

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There are quite a number of companies that make polyethylene tanks of all different sizes. There are a number of them that can make you a custom sized tank as well. They can be found by doing a Google search. I recently went through this in looking for a new potable water tank. It had to be fit into an odd shaped space against the hull. Almost nothing on a boat is square is it?..even stuff that is supposed to be square.

I don't know if it is worth trying to make one for yourself, especially when there are companies who have already made thousands of custom tanks and guarantee their work. If it does not work then you can send it back which is more than can be said if you try to do it yourself.

No glue or epoxy is going to hold together polyethylene or polypropylene, the material is just too slippery plus you will never get a chemical bond, only a poor physical bond. It has to be melted together so you get an excellent chemical bond. Polyethylene and polypropylene is very resistant to almost all chemicals that would weaken it, melt it or dissolve it. Being very inert, it also will not leech chemicals into your potable water. We use polyethylene sample containers on the research vessel for holding samples that are sometimes measured into the parts per trillion....they are that inert.
Ronco is the place for poly tanks. Not only do they have 450 (!!) different sizes and shapes of water tank in stock, but they also build custom. Each tank has the pickups and fill pipes custom located for your needs. They make nice quality heavy gauge tanks. I seriously doubt you could build one of anything like the same quality for less.


Ronco Plastics - Marine Water Tanks, RV Water Tank, Auto Detail Tanks, Water Tanks
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Old 19-05-2012, 03:45   #21
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Re: Building Water Tanks

If you got it wrong and a tank full of diesel leaked then the mess would be horrendous. I viewed a 33ft yacht that had a fuel tank leak over the winter and 20 gallons ended up in the shallow bilges, soaked into the ply bulkheads and stunk the boat to high heaven. I walked away from that boat.

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Old 23-05-2012, 11:42   #22
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Re: Building Water Tanks

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Ronco is the place for poly tanks. Not only do they have 450 (!!) different sizes and shapes of water tank in stock, but they also build custom. Each tank has the pickups and fill pipes custom located for your needs. They make nice quality heavy gauge tanks. I seriously doubt you could build one of anything like the same quality for less.


Ronco Plastics - Marine Water Tanks, RV Water Tank, Auto Detail Tanks, Water Tanks
I am familiar with their standard tanks, and I agree they are reasonably priced, perform well, etc. However, they cannot build serious baffles into them, correct?

I assume they can build custom tanks, including baffles, but only if they use the Tek Tanks type process we are discussing here. Tnat would be a different ball game and I assume such a custom tanks would be far more expensive.
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Old 23-05-2012, 11:57   #23
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Re: Building Water Tanks

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I am familiar with their standard tanks, and I agree they are reasonably priced, perform well, etc. However, they cannot build serious baffles into them, correct?

I assume they can build custom tanks, including baffles, but only if they use the Tek Tanks type process we are discussing here. Tnat would be a different ball game and I assume such a custom tanks would be far more expensive.


That's the reason I prefer to build an integral fiberglass tank in place. Maximum use of available room with no possibility of movement, chafe, corrosion, etc. Very beefy baffles are easy to build in.
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Old 23-05-2012, 12:33   #24
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Re: Building Water Tanks

I needed a new water tank, Ronco doesn't do customs anymore, and since they do roto molding, no baffles anyway. They do make good tanks however.

I consulted a plastic tank fab shop and my custom 55 gal tank would be 750 clams and 5/8" thick walls with one baffle and not really 55 gal because of wall thickness.

I built it out of 316L stainless in my garage for about $650 including welding wire and sheild gas. It is sized to alow a 1/2" air gap all around except for attach points. I included a sight tube so I can see the level at a glance. I can post pics later if anyone cares.

Just a thought.
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Old 23-05-2012, 12:39   #25
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Re: Building Water Tanks

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I needed a new water tank, Ronco doesn't do customs anymore, and since they do roto molding, no baffles anyway. They do make good tanks however.

I consulted a plastic tank fab shop and my custom 55 gal tank would be 750 clams and 5/8" thick walls with one baffle and not really 55 gal because of wall thickness.

I built it out of 316L stainless in my garage for about $650 including welding wire and sheild gas. It is sized to alow a 1/2" air gap all around except for attach points. I included a sight tube so I can see the level at a glance. I can post pics later if anyone cares.

Just a thought.
Stainless is good, but it is still subject to corrosion. Plastic is not subject to corrosion, so that is the advantage it has over stainless.
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Old 23-05-2012, 12:41   #26
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Re: Building Water Tanks

For others in the future, there is another company that makes custom polyethylene tanks that I ordered from. Darned if I can't remember their name now. But I bet you can find them on Google.
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Old 23-05-2012, 15:07   #27
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Re: Building Water Tanks

Tank Depot made a small custom tank for me, 3 fitting ports, welded poly construction $95 These are much more substantial than a rotomolded tank.....


Stainless is good, but it is still subject to corrosion. Plastic is not subject to corrosion, so that is the advantage it has over stainless.

Yeah, if it's going anywhere near the bilge or where it will get wet on the bottom when heeled, stainless aint too great. My 1985 boat had a SS tank in the bilge that was shot by '91. That's 6 years! I replaced it with a titanium one!
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Old 23-05-2012, 17:40   #28
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Re: Building Water Tanks

I chose stainless mostly for ease of fabrication. And where she sits is up in the bow, not an ideal spot CG wise but pretty much the only place where there is room, and that's where the old one was. It's sitting pretty far away from anywhere water can reach it save a near sinking. I thought of Monel but that's way too pricey and the stainless fuel tanks back in the lazeret are 40+ years old and still look great. They also have air gap all around. I guess I haven't learned to trust repeated water hammer on a welded plastic tank. It's my own ignorance I know, but....

Hey Cheechaco! How does one find a Titainium tank (of any size) for under a million bucks?
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Old 23-05-2012, 18:03   #29
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Re: Building Water Tanks

I ran an aerospace manufacturing facility. We had a few sheets of unused 1/8 6AL4V Ti around. Customer material that they designated as scrap. Got the shop to shear it up and one of my welders to weld it up etc... Man those Ti welds are pretty....:>)

An interesting note about Ti (and this $ info is a little old) Yea , Its expensive per pound, but it's the fabricating it into tubing or other stuff that makes things expensive. Back when SS was about $2 per pound, the Ti ran about $8-10 per pound if I remember right. Ti weighs 2/3 that of SS , so that would make the comparative price about $6 per pound. Let's say you were making a chainplate out of Ti and it weighed 5 lbs, $10 for SS , and $30 for Ti. However, welding Ti takes special processes to keep an Argon shield around the weld (front and back), lubricants using in forming SS do not work well on Ti (it's very abrasive surface finish, loks like cement under a microscope) thus mostly Aerspace fabricators know how to use it... and they have a big hourly rate....
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Old 23-05-2012, 23:46   #30
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Re: Building Water Tanks

I see, I work for a aerospace corp as well. We have some defense contracts and deal with some Ti parts but we don't do any of the processing in house. But having a full sheet metal and CNC machine shop I have fabrication opportunities that most don't. Our main focus is on advanced composite construction. Autoclave cure and RTM stuff. Kind of off topic but this thread is probably run it's coarse anyway.

Best wishes,
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