Fabricate Watertank

[Marshall Wright]

Greetings,

I need to have a new watertank fabricated for my Pacific Seacraft 25. About 12"x18"x5'.

I've been told that SS is prohibitive, that aluminum is the next best material, and that plastic is probably cheaper but will taste badly. I don't want to use a bladder.

I've also been told I can save some money by having a "non-marine" metal fabricator cut and fold the tank pieces to size and complete the finish welding and pressure test. Not sure what a non-marine company is....perhaps a regular metal fabricator?

The poly water tanks come in a variety of sizes that would probably work. And I could install all the necessary access ports and fixtures.

Is aluminum a better way to go, though?

Marshall

[Rachel]

I lived on a boat for a couple of years that had poly water tanks. Not sure what brand they were (could find out), but they were brand new only a few months before I joined the boat. The owner used a combination of ..... <thinks> perhaps baking soda and vinegar? (again, I can find out for sure).

Although I'm particular, am definitely not a fan of plastic, and would much preferred to have been drinking out of stainless tanks, I can't say that I ever noticed any "off" flavor from the countless gallons of water we drank out of those tanks. We did add a filter after we got to San Diego, because we noticed a major chlorine taste from the water there, and wanted to eliminate it, however we'd already been drinking out of the unfiltered tanks for months before that.

I don't like the idea of drinking from aluminum, but that's just me opining. I also think there may an actual good reason for not using aluminum water tanks -- perhaps someone else here can expound upon that.

Rachel

[Hirilondë]

Wow, a 56 gal. water tank on a 25 foot boat! Full it will weigh almost 500 pounds. Make sure it is in a good location.

Most boats come with fiberglass built in tanks. But if building in a new tank isn't a viable option I would opt for the longevity of a poly tank. You can always get an in-line filter or even a faucet mounted one if tasty water is a requirement. Most marina water is city water and doesn't taste very good anyway. I just carry bottled water for drinking and making coffee.

[Tim]

First off, get a quote on a custom stainless steel tank before you decide it's too expensive. Only a real quote will give you the information you need to make a decision; you may find that the cost is within your realm. Then again, you may not, but at least you'll have done the appropriate due diligence before abandoning the ideal.

Fiberglass water tanks are yucky and definitely "taste". They're in a lot of production boats because they're cheap and easy, but they're a poor choice in my opinion. Plastic would be a better option if you can't do SS.

From some of your posts, it seems you're doing a lot to this boat. In your situation, I doubt I'd hesitate to get the best water tanks available.

[bcooke]

I think the bad thing with alumimum is that it will corrode slightly and you will find yourself drinking a little aluminum oxide. I am not up on the specifics though.

I went stainless and they were not cheap. I have two tanks totalling about 50 gallons, one in the bilge and one replacing the V-berth tank, and the cost for the two tanks was close to $1000. A single tank would have been considerably cheaper of course since labor is a big part of the price.

I would definitely get a quote before giving up on stainless. I would expect to pay more but you will get a great tank that lasts a long time with no taste.

A couple of thoughts if you are going the custom tank route.

1.) Think out every detail and be explicit when you talk it over with the fabricator. Nothing is too insignificant to clarify. Sizes of threaded fittings and such come to mind. Don't leave anything to the fabricators discresion. Or at least have them explain their recomendations.

2.) Build a mockup. You might be surprised to find that the tank that fits so well in that perfect location is impossible to maneuver into that position. I know a couple of instances where this was a surprise to boat owners (including me) Think out how all the connections are going to be made, their sizes, and their routing.

3.) Don't forget baffles...

Expensive? Yes. But probably the most perfect option if you can afford it.

What the boat wants, the boat gets...

-Britton

[triton318]

I came across a plastic welding tool about a year ago when I was doing some research into water tanks. Apparently, with this tool (which wasn't too expensive), you can weld poly panels. I don't believe this material is very expensive, so I guess you could buy poly panels, the welding tool, and construct a custom-fit water tank for a modest amount of money. I'm just guessing, of course. Does anyone have any knowledge or experience with welding poly?

[Ceasar Choppy]

I came across a plastic welding tool about a year ago when I was doing some research into water tanks. Apparently, with this tool (which wasn't too expensive), you can weld poly panels. I don't believe this material is very expensive, so I guess you could buy poly panels, the welding tool, and construct a custom-fit water tank for a modest amount of money. I'm just guessing, of course. Does anyone have any knowledge or experience with welding poly?

I don't have direct experience with welding poly, but IMO you really need to know what you are doing to make sure its done right. I use these guys to make my polypro tanks:

http://www.triplemplastics.com/

I haven't done these for water tanks (yet), but they built me a holding tank and fuel tank and were fairly reasonable. While rotomolded tanks are arguably more rugged (all one piece), welded polypro tanks can be fitted with baffles unlike rotomolded tanks.

[David VanDenburgh]

2.) Build a mockup. You might be surprised to find that the tank that fits so well in that perfect location is impossible to maneuver into that position. I know a couple of instances where this was a surprise to boat owners (including me). -Britton

Britton's suggestion reminded me of my own experience while trying to find a suitable replacement for our holding tank. Yes, a mockup can save a lot of frustration and money.


This one made it clear that an almost-direct replacement wasn't going to work.

David

[Rachel]

Let me IN!