Nauticat 52 Refit

[DeepFrz]

Wonderful way to renew an old tank. I'm sure this thread will help many people with older boats.

[minaret]

Originally Posted by Exile

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 . . . .

Anytime, glad to see its got some of you thinking!

[DeepFrz]

minaret, I recommended this thread be made a sticky.

[minaret]

Originally Posted by Exile

Looks like trouble to me . . . DOUBLE-trouble in fact!

Too true!

[s/v Jedi]

I believe you can also bond PVC pipe to fiberglass by putting a flame on the PVC until it just starts to blacken before bonding it... I never did this but it's stuck in my brain somehow.

[minaret]

Originally Posted by cpa

Minaret:

Wow this tank segment has got me thinking. The aft section of the Compass's keel has two tanks. The aft one was a diesel tank of about 35 gallons. The forward was a gray water tank and holds 25 gallons.

The forward one is in great shape, but the aft fuel tank is rough. I always thought that it would be nice to figure out a way to re-glass it, but have always wondered about getting the surface sanded well enough to re-glass. The tank is very thin and very deep. It would be nearly impossible to get any type of sander in there. Do you have any advice or should I just throw a water bladder in there and call it a day?

Thanks

I think a bladder is a bad idea in most cases, chafe will kill it quick and they aren't cheap. There is a newer type if rigid bladder that is an option for very tight or complex spaces. The bladder has a double wall, with space between filled with a heat sensitive resin. You get a bladder of the approximate size, insert it in the tank/space, and inflate a balloon inside of it to make it conform to the shape. Then you heat it to make the resin kick off. Once it starts to kick you can pull the balloon out and put a heat lamp inside to cure it. Voila, insta-tank! Only done it a couple of times, don't remember the product name. Believe it's been discussed on the forum.

That said, it only cost me a few hundred bucks in materials and a whole bunch of time to do mine. You considering doing yours in place because it would be too hard to remove? A regular bladder is not so bad for water, at least if there is a total failure it won't make too much mess. If you use the original tank for a mold it just needs to be really clean, you don't really need the glass to stick to the original tank. That bond will fail before long anyway. You are just using the original tank as a mold.

[minaret]

Originally Posted by SVTatia

Excellent Minaret. Thanks for this, very interesting and smart.

I have one question:

1) How is this about bonding PVC to fiberglass with methacrylate. Where do you get the metha? Looks like you did a layup using matt?

I will need to increase the cockpit drains and was thinking of using PVC pipe but not sure how to bond it to the fiberglass.

I love methacrylate, I use a lot of it. I prefer Plexus for marine apps, but it is damn expensive, and hard for the average mortal to acquire. Here is my secret cheap alternative. I swear it is exactly the same product for a quarter the price, although they describe it as an epoxy. It's definitely methacrylate, unmistakable odor and properties. Does a great job for a fraction of the price, I've destructively tested it. Good luck getting that apart! Much easier to find too. That's just a tongue depressor fillet. Very strong with schedule 80.



Permatex® PermaPoxy™ 84115 - Plastic Weld Epoxy | O'Reilly Auto Parts

[minaret]

Originally Posted by DeepFrz

Wonderful way to renew an old tank. I'm sure this thread will help many people with older boats.

I certainly hope so Frz!

[minaret]

Originally Posted by s/v Jedi

I believe you can also bond PVC pipe to fiberglass by putting a flame on the PVC until it just starts to blacken before bonding it... I never did this but it's stuck in my brain somehow.

Never heard that one before. Sure would be cheaper than methacrylate. However, a methacrylate fillet sure does add a lot of strength to the joint, especially if you can do one on both sides like this.

[minaret]

Originally Posted by DeepFrz

minaret, I recommended this thread be made a sticky.

Tell the mods, man! I can't sticky it...


I post often enough that its usually front page anyway.

[DeepFrz]

I did tell the mods. Hopefully it will be sticky soon. I know its upfront now but it wont be when you finish and its to valuable a thread to get lost in the archives.

[SVTatia]

Originally Posted by minaret

I love methacrylate, I use a lot of it. I prefer Plexus for marine apps, but it is damn expensive, and hard for the average mortal to acquire. Here is my secret cheap alternative. I swear it is exactly the same product for a quarter the price, although they describe it as an epoxy. It's definitely methacrylate, unmistakable odor and properties. Does a great job for a fraction of the price, I've destructively tested it. Good luck getting that apart! Much easier to find too. That's just a tongue depressor fillet. Very strong with schedule 80.

Great hint on the Permatex - I'll check if I can find it around here.
In the picture it looks like it is a laminate, but it is just a fillet? Could you laminate mat with it?

[Exile]

Originally Posted by minaret

I love methacrylate, I use a lot of it. I prefer Plexus for marine apps, but it is damn expensive, and hard for the average mortal to acquire. Here is my secret cheap alternative. I swear it is exactly the same product for a quarter the price, although they describe it as an epoxy. It's definitely methacrylate, unmistakable odor and properties. Does a great job for a fraction of the price, I've destructively tested it. Good luck getting that apart! Much easier to find too. That's just a tongue depressor fillet. Very strong with schedule 80.



Permatex® PermaPoxy™ 84115 - Plastic Weld Epoxy | O'Reilly Auto Parts

It says it will not bond most polyethylene or polypropylene plastics. I'd like to say I'm not up on my "poly's," but truth be told I really have no clue. Are these two poly's something we typically find onboard?

[bobconnie]

Ahh the pic's of the girls sure makes me think back ! lol We had the 3 girls aboard till they went off to collage ! Ahh they all went to the proms at the same times lol always remember the extra hours I put in at the machine shop to pay for em ! but i would do it again anytime !! Ya just gotta love those little girls, but darn were boys easier to raise up lol Great looking children ya got there !! Just like your boat !!!

[minaret]

Originally Posted by DeepFrz

I did tell the mods. Hopefully it will be sticky soon. I know its upfront now but it wont be when you finish and its to valuable a thread to get lost in the archives.

Thanks man!