Temporary Holding Tank Fix

The dreaded holding tank. Everyone who cruises and has a traditional style head and holding tank will eventually need to ‘deal’ with maintaining this system. Unfortunately for us, our time was this week. We had already given Marina Cortez notice we would be leaving, twice, and so, naturally, we came up against a repair that meant we needed to stay a few more days. They probably think we’re a little nuts up there in the office.

A few days ago Mike and I tackled a job we’ve been putting off: we replaced the hose that goes from the holding tank to the aft head. While we were doing that job I noticed some nasty looking liquid in the storage compartment in front of the tank. Yes, the tank was leaking. From the bottom. The amount of sighing this caused cannot be overstated. In order to reach the leak, we’d have to remove the tank. That meant taking stuff apart. That meant the boat was about to get messy again.

We are really lucky aboard Galapagos because our tank is pretty accessible. It’s under the midship berth. You can lift a heavy wooden cover to access it. Getting the tank out requires a bit more disassembly, but it’s not nearly as hard as it would be in our friend’s Tayana 37.  Theirs is under the engine. Enough said. We’re grateful for small things like this.

The crack is located to the right of Mike’s arm, down underneath.

After the marina’s pumpout service came by, we used this nifty little tool to get the rest of the liquids out of the tank. Mike uses this to change the oil in the engine. Makes getting the oil out, or the black water out, pretty easy. By this time, there wasn’t much in the tank. 

After getting the tank free from it’s home, we saw that, indeed, the tank was actually cracked right by the seam. We were hoping that a seam had given way, but it was a real doozy of a crack. Honestly we can’t figure out how this happened. But whatever, it was leaking like nobody’s business. I whipped out the bleach water mighty fast.

The tank is plastic; believed to be made of polyethylene. This is a substance that resists fixing unless you have exactly the right stuff. We didn’t. We weren’t even exactly sure that the tank is made from this stuff. It could be ‘poly’ anything. But we did know that given the right materials, we should be able to heat weld a fix to the tank. But how to go about getting the right materials here in Mexico? We started with putting out our need on the morning cruiser’s net on the radio. We got nothing there. Moving on, Mike’s research brought up a plastic supply place within walking distance. I put on my Teva’s and we went off into the bright Mexican sun, still feeling confident we could get this fixed. We enjoy the feeling of confidence that comes with ignorance.

The offending crack.

Unfortunately, we speak so little Spanish that we have to use photos and a lot of sign language and Google Translate (which is frequently wrong, by the way) to get by. The young man behind the counter at the plastic supply was having none of it. I pointed to my photo of the tank. He shook his head no and looked straight ahead. Mike brought out the plastic welding rods he did have already (wrong stuff, right shape) and the lad shook his head vigorously ‘no’ again. We showed him more stuff. Frankly, he just wasn’t interested in helping us. We decided to look around the store and see what jumped off the shelf at us. We could smell plastic resin. They make plastic stuff there. Surely…

Mike found some small trays that looked and felt like the exact stuff our tank was made of. We bought two for 85 Pesos, about $4.50. Our hopes soared as we walked back to the marina, still believing in fairies.

I do not understand this face. But these are the trays. Pretty nice trays, too.

Back at Galapagos Mike cut strips of plastic off the trays and set to work. Using the multitool (part of our Ryobi rechargeable tool sets that we cannot live without) he ground out the crack back to clean plastic, then used the sander to sand the surface with heavy grit, then cleaned the surface with acetone.  He got out the butane torch and began laying the plastic into the groove. It looked good. The stuff melted easily and flowed into the crack. We thought we’d hit paydirt.

We were wrong. As the plastic melted some of it began to bubble and when those popped they left pinholes. In the end, the pinholes leaked. Back to the drawing board.

That’s a butane torch.

Well, not exactly that fast. We did a lot of other things like add more material, remelt and try to smooth the existing material, and use the heat gun, which actually worked pretty well. But the weld was not a good one and the tank still leaked. We didn’t know if we had the wrong temperature, or the wrong materials, or what. We’d had to peel a thick layer of rubber off the side of the tank and the plastic underneath was discolored. Mike thought perhaps the plastic was somehow contaminated.  But whatever the problem was, it was wrong. And, by the way, this is why there are professionals who know about this kind of stuff and do it for a living. Most places.

Another cruiser came over and took a look and lent us his wood plane. Mike used that to shave off thin strips of material off the corner of the tank so that we could use the exact same material the tank was made from and try again. I routed out the old material, exposing the area of the crack again. Oddly, some of the stuff we’d just done had welded great. But not good enough to keep those pinholes from leaking.

We laid the small strips of tank material in the groove and commenced with the heat. It melted well, seemed to adhere well, and there was less bubbling. I thought we were onto something. Alas.

Still another cruiser came by and offered us some blue plastic stuff he used to repair his poly…something tank 10 years ago. It was still holding after all that time. He suggested a propane torch, which was what he used. With nothing to lose but our sanity, we sanded and cleaned the surface again with acetone. Because of the wind, the torch had trouble staying lit. But Mike finally got the stuff to melt and the surface of the tank to melt enough to hold it. After letting it firm up he tested it and the strip of blue plastic peeled right off. Things were not looking good. I decided it was time to try to find a professional. At this point I was ready to pay someone else to get frustrated.

We used the propane torch on this stuff. Honestly we thought this would work. Everything went all melty. It peeled right off.

We contacted La Paz Cruiser’s Supply and got a phone number of a guy who welded plastics. It was disconnected. Then I contacted a long time resident of La Paz who has his finger on the pulse of boat works around here and had given us a tour of all the marinas and boat yards. He used to own a yacht management service and is a marine surveyor. He said there were no plastics welders in La Paz. He should know. He said we might have to get a fiberglass tank built to spec or we could probably order a new tank through Lopez Marine for $$$. To me that sounded like a lot of money, but mostly a lot of time, and also our tank should be reparable with the right materials and know-how.  He also suggested a special repair kit for plastic tanks sold by Autozone. Leaving Mike to perseverate over the tank, I Ubered to Autozone, only to read the back of the package where it says, ‘Not to be used on Polyethylene or …’.   Back to square one.

This is the stuff. A different brand than what we used before, but equally good.

I texted Mike and told him it was a ‘no go’ in terms of the plastic repair kit. He decided to try one more thing. This is the ‘one more thing’ that will get us off the dock on Saturday for however long it holds up; the ‘one more thing’ that will buy us time until we can find someone who can do an appropriate repair.  And that one more thing is this wonderful Pro Flex All Weather Water Proof Butyl Roof Repair tape we keep on board. This is the stuff we got to replace the sealing around the little rectangular ports on our hull above the waterline. It has worked so well that we keep it on board for other possible uses. And now we found one.

When I returned to the boat the tank was standing up on the dock, full of water and not leaking. The rubber was holding the leak back. I reinforced Mike’s taping with a couple more strips of this magic tape and now we’re good to go, as long as this holds. We have no idea how long that will be. I mean it could last as long as next week, or as long as 5 years.  But however long it is is better than sitting here on the dock right now. We can easily keep an eye on this since now we know exactly where the leak is.

Now that the tank is back in place we’ll be getting a can of that expanding foam and putting a bead of that under the leading edge of the tank. We believe there is not enough support for the tank in this location and that led to the eventual cracking. There is plenty of room for the foam to expand without causing a problem.

All taped up and ready to rumble again.

One of the good things that came out of this little setback was that we were able to get a good look inside our tank. Remember that fun science experiment we did with the Zaal No Flex Digestor; the one where we demonstrated what a good job it does at dissolving solid waste and toilet paper? Those results held true. What could have been a nasty, stinky job was really not bad at all. When we opened up the hose connections we could see into the tank and there was zero buildup inside. Much to people’s dismay, we actually do put about half of the toilet paper we use into the holding tank. So let me state this again: we had zero buildup in the tank, and the aroma was nothing like you’d expect. No gag reflexes were engaged.  I’m sticking with my Zaal NoFlex Digestor and the toilet paper is going to continue to go into the tank.

And now we are hoping to leave La Paz on Saturday to go to the islands and really begin seeing the Sea of Cortez. Shh. Don’t tell the gods of cruising. We don’t like to tempt them openly. Nothing to look at here….nothing at all.

Before we sign off, someone is bound to bring up getting a composting head. We’re not ready to do that at this point. We’d have to order it and wait around for it. Then that’s another boat project. We’d rather be cruising. In the future, if this tank issue can’t be resolved, then maybe. But it’s been a bulletproof system until now. It’s a good installation that has lasted since the 1980’s. If we can fix what we have, we’ll keep it.

S/V Galapagos, out.

6 thoughts on “Temporary Holding Tank Fix

  1. “We enjoy the feeling of confidence that comes with ignorance.” This may be my favorite quote ever. BTW, give the composting head a pass.

    • Feel free to use that with impunity! Yes, we remember the way you hated that composting head. We’ve heard many horror stories of them and have no plans to change over. Lots of people love them, though.

  2. Love this post! Explains so well the trials and tribulations of getting/finding/doing things down here, as we’ve come to learn with our solar panel project. On another note, the Zaal has been ordered after reading your wonderfully forensic write up of your poo experiments.

    We hope you get to head out as planned tomorrow.

    • You will absolutely NOT regret the Zaal. And I do think they should give me free product considering all the sales our little experiment has sent their way. Still, it’s a great product even if I have to buy it myself. We are so out of here tomorrow!All provisioned up and ready to go.

  3. Again, I learn some extraordinarily useful bit of arcana from Littlecunningplan. The butyl roof repair tape has been ordered! Now, get out there and enjoy the Sea of Cortez before it gets too hot (you have three months). warm regards, Don

    • Ha! You will be glad about that butyl tape any number of ways! We’re out here and enjoying every bit of the SOC. Thanks for reading and always leaving such nice comments.

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