Minaret -- your photo
essay on restoring your "poo" tank was quite valuable to me & I'm sure many others. I admire not just your skill-set, but also your COURAGE
, for cryin' out loud!
When I was trying to figure out how to deal with my leaky aluminum
55 gal. diesel
tank last year, I looked into different ways to coat it -- either on the inside or out -- but ultimately wound up replacing. I found a less-than-fully-employed boatbuilder
(quite a few of those guys around these days, regrettably) who used the old tank as a template and made me a new one using fiberglass
. He did it outside
the boat, however! Still, the new tank -- tapered to conform to the hull
-- fit back into the hull
perfectly. Still not entirely sure how you guys pull stuff like that off.
Anyway, I had no idea you could also accomplish this while a tank is inside the boat, and am astonished you can use the old tank as an outside mold
. In my ignorance, I always figured for whatever reason that one would glass over
the existing structure & not the other way around. Whodathunk?! Of course, in your case it didn't look like you had much choice.
My interest is piqued because I have another diesel
tank that was abandoned long ago by the PO since it is under the galley
sole and would be a big PITA to gain access to. It is also rather small, so maybe not worth it. More importantly, I also have 3 f/w tanks
that I believe are also original (1986). They are either SS or Monel (don't know how to tell the difference), are not leaking (yet), but do show some surface corrosion
on the welds.
If your tanks are Monel they will have a particular color, google it. If they are they should be good for a very long time. Probably SS if they have visible corrosion though.
So a couple of totally noob questions about building your new tank:
1. You mentioned that this could be done with any sort of tank. I know there are certain epoxy
coatings to use for diesel, but are there reliable products for potable water
? The West Systems manual seems sort of equivocal on this. What coating, if anything, will/did you use for your black water
tank? Or will the 2000 itself suffice?
[COLOR="rgb(75, 0, 130)"] Yes, in fact there have been several recent threads on the subject, do a forum search. The product we use is hard to get and comes in industrial quantities, minimum five gallons. But it is designed specifically for sealing fiberglass
potable water tanks in boats. 2000 is sufficient for a black water tank, and in fact Interlux
recommends it for diesel and grey water tanks as well. 10 mil DFT is required, I like to do six coats.[/COLOR]
2. Similarly, are there certain resins you want to use or avoid, depending on tank usage?
The sealer does all the work in that regard, so I think the cheaper the better for tank construction, to a point of course. To me that means poly iso resin, woven roving, and lots of matt.
3. Why not leave the original tank structure in place like you presumably had to do with the tank bottom? What sort of release agent did you use for the walls so you could cut them away?
[COLOR="rgb(65, 105, 225)"] In this case, most of the tank was left in place, only the top and 2" of the side were cut out. Release agent is good old Partall Paste #2, never fails you.[/COLOR]
OK, enough for now. Thanks again for taking the time to post this stuff. Can't wait for the next episode . . . .