Potable water tanks

I have an 81 Island Gypsy, the potable water tanks were buikt with a rivited construction, out of something calles monel (sp). Similar to galvanized. No corrosion oroblems, but they hava had leaks. PO made service ports into the tops of each, and calked seams repairing the leaks. Well time marches on. I had to take a 90 gal out of service to repair it again.
I have been searching for an epoxy to coat the inside of the tank, posibly making a near perminant repair. However, finding an epoxy rated for potable water and available to a consumer, in the u.s. has been challenging. I found a product called interline 925 (https://www.international-marine.com/product/interline-925) that seems suitable, but purchasing has been a bust.

Anyone either have a lead on another suitable product, or a source for this? And no, removing water tanks is not a feasable project. I use bottled water for drinking 99% of the time, but still want the water to be safe.

I use Interline 975, but you have to get it from an industrial supply. I think the smallest size is 5 gallons. It's not cheap, but lasts decades.

Coating for small and large water tanks, boat water tanks,sistern coating, safe for food contact, aquaculture, fish safe. For use on potable water tanks,brewing tanks, etc. This coating is for water tanks and brewing equipment. Comes in 2-1gallon jugs 2 part. $220

Have you considered replacing the tanks with modern plastic tanks?

rwidman said:

Have you considered replacing the tanks with modern plastic tanks?

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Thought about it. Extensively. 2 of the 5 tanks it would be possible, and if they ever give me trouble, just might do that. The other 3, well just too much to remove. Correction, I could cut the tanks apart and remove them, but replacing them would be weeks and weeks of labor and materials to attempt to put the interior back together. It's possible, but it is about the last option on my list of remedies.

jgtrucking said:

Thought about it. Extensively. 2 of the 5 tanks it would be possible, and if they ever give me trouble, just might do that. The other 3, well just too much to remove. Correction, I could cut the tanks apart and remove them, but replacing them would be weeks and weeks of labor and materials to attempt to put the interior back together. It's possible, but it is about the last option on my list of remedies.

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Keep in mind, if you replace a tank, it doesn't have to be with one of the same shape / size. You can always put 2 or 3 tanks (tied together to act as 1) into a space if that makes getting them in and out easier.

Could you use existing tanks and install bladders in them?

Lepke said:

I use Interline 975, but you have to get it from an industrial supply. I think the smallest size is 5 gallons. It's not cheap, but lasts decades.

Coating for small and large water tanks, boat water tanks,sistern coating, safe for food contact, aquaculture, fish safe. For use on potable water tanks,brewing tanks, etc. This coating is for water tanks and brewing equipment. Comes in 2-1gallon jugs 2 part. $220

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Cost isn't so much an issue, as it will be cheaper than removing 80% of the interior and rebuilding it I think the link you posted will be a suitable alternative. I will post my results.

Pack Mule said:

Could you use existing tanks and install bladders in them?

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Yes, in theory. Kinda what I would be doing, making a bladder with epoxy. The plumbing is where a bladder gets troublesome, as I need the fill, vent, and draw plumbing to line up with the tank.


Also, there is no corrosion, essentially I do not need the top coated. The riveted seams in the corners are where they give. I may only need to coat the general seam areas, not the entire interior of the tank. I will inspect more carefully before placing an order. I just hadn't found a product to order. Lepke's link is real promising though.

rslifkin said:

Keep in mind, if you replace a tank, it doesn't have to be with one of the same shape / size. You can always put 2 or 3 tanks (tied together to act as 1) into a space if that makes getting them in and out easier.

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Very true. The 3 troublesome tanks (90g, 90g, and 50g) are belly tanks. Under the floors and bulkheads, but yet well away from the bilge.

jgtrucking said:

Very true. The 3 troublesome tanks (90g, 90g, and 50g) are belly tanks. Under the floors and bulkheads, but yet well away from the bilge.

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I've got one like that to replace. Plan is to get enough access to un-strap it and then slide it to a large enough opening (I won't need to cut, but you could if needed). Might end up making a new floor hatch in the process. New tank will be 2 tanks as that's the only way to get stuff back in there for the capacity I want.

Fwiw, Monel Monel is a copper nickel alloy, well known as a corrosion and rust resistant material that's stronger than steel. It's also very expensive, so if you decide to replace anything made of Monel, don't just send it to the dumpster!


More info: https://www.lenntech.com/monel.htm


--Peggie

HeadMistress said:

Fwiw, Monel Monel is a copper nickel alloy, well known as a corrosion and rust resistant material that's stronger than steel. It's also very expensive, so if you decide to replace anything made of Monel, don't just send it to the dumpster!


More info: https://www.lenntech.com/monel.htm


--Peggie

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Very interesting article Peg... Now if they had only welded or soldered them instead of seam and rivet... Maybe that was a cost cut in the wilds of Hong Kong where she was built.

It occurs to me that the tanks might be removed (in pieces if necessary) and remade as smaller and/or fewer tanks.



--Peggie

Hi jgtrucking,

Well, your posting provides yet another example of the virtue of this forum. The ability to learn new things all the time! As an (ahem) veteran of decades of both professional and personal involvement with marine systems, this is the first time I've run across a recreational powerboat manufactured (presumably OEM) with RIVETED water tanks. And monel, at that! Huh, who'd a thunk?

A question for you: how did you determine the tankage is, indeed, monel? Rare as hen's teeth, particularly in 80's-vintage recreational powerboats.

Anyhow, given the material is monel as you profess, with adequate access into every baffled compartment of the tanks, I heartily suggest you do NOT remove the tanks for either repair or replacement. They're certainly way too valuable to replace with "modern" materials such as plastic.

The link that Lepke provided shows promise for repair of your leakage issues, given (again) you have adequate access to the entire interior of your various tanks, and the leakage rate isn't too aggressive. It's unlikely any sealant will be able to deal with leak rates in excess of maybe one (1) gallon per hour, but that's just a SWAG on my part. Your mileage may vary, and given the extreme difficulty and expense of replacement of tankage, attempts to seal these tanks may well be successful.

It appears the viscosity of the linked product is quite high (3100 cp), way above that of latex paint (100cp, for instance). So application may be a challenge, but you should have reasonable assurance that the coating would not all sag off and puddle at the bottom of the tanks, before it's had a chance to seal any voids. A conversation with the vendor of the product would be well worth your while prior to committing.

Once sealed to your satisfaction, with a product suitable for use with potable water, I personally have no issue with potable on-board water tankage. But that's assuming you maintain the water quality properly, per Ms. Peggy Hall's instructions. Sure beats dealing with bottled water aboard, by far.

Regards,

Pete

Yea they are, per the po, the former dealer, and the properties of the tanks. The thing i dont get is why they were not welded. Built in 81 in Hong Kong, maybe that was a cutcorner. Who knows. Given where the builder located them, i doubt they would have survived 40 yrs if theh were another material. Instead of baffles, they are seperate tanks. The 2 90 gal forward could have been 1 180.

The po cut in the tops and made the resealable inspoction ports i have to work with. He had issues years back, and was told they were not repairable. Well he was alot like me, dont tell me i can't, i'll find a way. He calked the seams that leaked. This worked, and could work again... but i think the epoxy approach could be closer to a perminage fix.

Fyi i do diligently maintain the tanks to remain potable, but the ice maker, and occasional coffee is all we drink from them.

I've have Monel tanks that are riveted. You can solder the joints to seal them if you can get to the joints. I did a very sloppy but successful repair for just a few bucks. Somewhere I saw a soldering gun that was pretty long that might help with getting to the leaks.

Remember that it isn't structural, just fixing a leak.

BTW, mine came in a sailboat built by American Marine (Grand Banks) in Hong Kong in 1963. The tanks still look like new except for the snotty looking repair I did

Monel is, as others have said, a wonderful material and highly corrosion resistant. It has a special quality to those of us who have been in the trade for a while because it is essentially corrosion proof, and now very rare. It usually has a slight green patina. A metal recycler might know what it is and might pay for it. I've seen too many Monel tanks removed and discarded just because they were old. Riveted...that is even rarer.

OK, now that I've gotten past the sentimental part, if the tanks are riveted and leaking, there's no harm in trying to repair the leaks with sealant or soldering if you can access the area, but the tank is a large heat sink, so getting them hot enough, and the area clean enough, to solder won't be easy.

Unless you are simply doing a spot repair at the leak location, and you mentioned that's an option, I would strongly recommend against trying to coat the entire interior for two reasons. One, if the tanks are baffled you won't be able to access all of the compartments, and even if not baffled, reaching all of the interior from the port may not be possible. Two, in order for tank coatings to work, and last for a long time, the interior of the tank needs to be spotlessly clean. That's hard to achieve even on a stainless tank, much less Monel with the patina it develops. Once you apply the coating, you are committed, if it fails, you are stuck with a tank that can't be used as the coating will clog plumbing and pumps. Did I mention coating is a bad idea?

If you try to spot seal from the inside, getting the repair area absolutely clean, and slightly rough, will be key to a long-lasting application.

Andiamo2018 said:

I've have Monel tanks that are riveted. You can solder the joints to seal them if you can get to the joints. I did a very sloppy but successful repair for just a few bucks. Somewhere I saw a soldering gun that was pretty long that might help with getting to the leaks.

Remember that it isn't structural, just fixing a leak.

BTW, mine came in a sailboat built by American Marine (Grand Banks) in Hong Kong in 1963. The tanks still look like new except for the snotty looking repair I did

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That would have been built during Tony Fleming's tenure at AM. Some great video on the yard and operation there here

The strip planked boat being built might be my very sailboat! It was completed in '63 and the framing and ribs are placed just like my Caulkins 40.

I went down the rabbit hole a bit and found this picture from the yard:



Same construction as my tank.

My tanks still look like stainless inside and out btw. There is no patina, just clean shinny metal. It was also pretty easy to solder it. The solder just needs to get into the joint. Even at the bottom of the tank there isn't that much pressure.

Andiamo2018 said:

The strip planked boat being built might be my very sailboat! It was completed in '63 and the framing and ribs are placed just like my Caulkins 40.

I went down the rabbit hole a bit and found this picture from the yard:

Same construction as my tank.

My tanks still look like stainless inside and out btw. There is no patina, just clean shinny metal. It was also pretty easy to solder it. The solder just needs to get into the joint. Even at the bottom of the tank there isn't that much pressure.

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I recognize that tank construction method, I've seen it before. But is it riveted or soldered? Those blobs look like solder. Tony's photos from the region are simply mesmerizing, a bygone era.

On my tank there are rivets in a blob of solder It looks just like this one.

A bygone era for sure. Things were probably simpler then but at the expense of anyone who wasn't a white guy lol I probably would have been ignorant but happy...

From Tony Fleming...

"The tank would have been stainless steel. We never used Monel. The tank construction was the old traditional style with double turned
edges where the sides met the top and bottom. That joint was sealed with solder which was only on the outside of the tank. The photo you sent shows the tank being pressure tested. In the photo you can see the rivets holding the baffles. They too were sealed with solder externally. We built quite a number of strip planked Caulkins 50’s."

More from Tony...

"I'm not sure whether your correspondent spotted his possible Caulkins in the video. He would need to have sharp eyes to spot it as it was really small in a vertical picture at around 06-10 in the video. After receiving your mail I went back and took a look through the video and was able to spot it.

Attached is a blow up of a small part of the frame and it is a Caulkins which is a double ender. The other boat being planked earlier in the video is being double planked - not strip planked."

That was exactly what I saw!

I have a Calkins 40 and it has a clipper bow. Somewhere I have a magazine article from 1963 that has a picture. The caption says that only the first two hulls had clipper bows as pictured and the others had a spoon bow.

I can't find that article right now.

Here is a picture of her sailing:




http://www.captdan.net/uploads/2/1/1/1/21113348/1963058_orig.jpg

Steve DAntonio said:

More from Tony...

"I'm not sure whether your correspondent spotted his possible Caulkins in the video. He would need to have sharp eyes to spot it as it was really small in a vertical picture at around 06-10 in the video. After receiving your mail I went back and took a look through the video and was able to spot it.

Attached is a blow up of a small part of the frame and it is a Caulkins which is a double ender. The other boat being planked earlier in the video is being double planked - not strip planked."

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