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Discussion Starter · #1 ·
I made it to Dragon Wing this weekend and managed to pull my old prop in significantly less time than I expected. So, I decided to start on another job, one that I thought wouldn't take too much time - replacing the hoses in the head. I was wrong, it wound up taking a lot more time than I expected.

I have a Todd holding tank, which is a polyethylene tank. As I struggled to get the hose off the intake fitting, I realized that the area around the fitting was having a problem - it was coming free from the body of the holding tank. You could see where the fitting was attached to the tank, and the tank was cracking along that line. I don't have the time or the inclination to replace the holding tank right now, so I reached out to Todd yesterday (Sunday) to see how they recommend sealing the crack. I expected them to say "just buy a new one" and be done with it, but thought it was worth a try. When I woke up this morning, I had an E-mail from them suggesting 3M 5200 as the sealant. They said that it was the only thing that they've seen that actually stays bedded with any reliability.

So, I'm passing this along in case others need it. I searched online last night, and the only recommendation was plastic welding. I can't imagine heating a holding tank, even an empty one, so this wasn't really something I wanted to try (better in that case to replace the tank!).
 

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Well ! That just stinks ;) Sorry ta hear of year woes.
5200 *may* be the way to go; but yanno it'll come back to bite ya later..at the most inappropriate time . Just shows ta go ya..all projects estimated end up at 2X the $$ and 3X the time.

regards,
Paul
 

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So, I'm passing this along in case others need it. I searched online last night, and the only recommendation was plastic welding. I can't imagine heating a holding tank, even an empty one, so this wasn't really something I wanted to try (better in that case to replace the tank!).
After I bought my previous boat, I discovered that the plastic holding tank had cracked at the fitting just like you described. Apparently the PO tried to repair it with something, not sure what. Unfortunately, the repair did not work. May not have bothered the PO because he used it as a day sailor. Anyway, I just replaced the tank so I can't comment on a repair.

But, I'm wondering why you want to avoid plastic welding? I've repaired several kayaks that way and it is easy and permanent. You don't really heat the tank, just the plastic welding rods. (At least that's how it's done with kayaks.)

Good luck with your repair. I hope spring comes soon!
Jim
 

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Polyethylene is a ROYAL PITA to fix. Most 'plastic weld' two part glues or epoxies simply do not work due to lack of adhesion (PE is very slick) and differences in flexibility (PE is flexible, the weld is not, so the bond breaks very fast).
If it is a big crack in a place subject to stress, and that is most likely the case (it would not break if there was no stress) I would just replace the tank. If you want to chance it, use a thicker rubber patch and rubber glue - as they are flexible and the glue adheres to PE in a fairly decent way.
 

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West Systems' G/Flex is very good at welding PVC and other plastics. There was an article that the Gougeons did about how they fixed a plastic kayak, and I myself fixed a PVC flexible furler. It's good stuff.
Thanks for the tip. But PVC is a totally different animal then polyethylene. Very easy to fix (as in 1) compared to polyethylene (as in 10). But I do need to try that product on one of my PE projects.
 

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Good luck with it.

My boat also came with a Todd holding tank and had the same crack. I ended up replacing it, which is worth a lot of peace of mind. I also setup the new holding tank with all fittings at the top (using a dip tube for the pumpout) and that makes me feel a lot more comfortable with it. I never have sewage just sitting in lines or fittings anymore.

It was a messy job, but well worth it.

The new tank (Sealand) is also a lot thicker than the Todd one was.
 

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Getting cracks in the tank, even after it has been mechanically stressed by trying to remove the hose, is a good sign that the plastic is getting brittle in general. I would replace the tank rather than risk finding more cracks in the near future.
 
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We had a leak in our tank. It is the original to the boat. John brought it home (nice 2-hour drive), hosed down the inside, sanded the crack area, applied water weld, and did a very extensive pressure test in our driveway with meters and whatnot. It didn't leak in the driveway. When we got it back onto the boat, it started to leak again. Possibly due to the flexing? I don't know. We're going to buy a new one. The new tanks have thicker walls than the original.
 

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Asleep at the wheel
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Discussion Starter · #18 ·
Wow, I wasn't expecting this kind of response. LOL

I do plan to replace the tank, probably somewhere in the middle to end of this season. I just don't have the time for it now. I have several other projects, including finding the source of some pretty major leaks, that are higher priority. So, if I can patch it for now and help keep it from stinking up the cabin, that's sufficient. We're day sailors, MAYBE weekenders, not cruisers, so we won't be using the holding tank much anyway. I'll be getting the boat pumped out every time we return to the slip and the tank is used.

The tank is in a fairly small space, so I only have a 9 gallon tank right now. I'll have to look a the other tanks, too. I'll also compare them against composting heads and other options. If I'm going to spend the money, I may as well see what else will work. But that's something to research in a few months.
 

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Wow, I wasn't expecting this kind of response. LOL

I do plan to replace the tank, probably somewhere in the middle to end of this season. I just don't have the time for it now. I have several other projects, including finding the source of some pretty major leaks, that are higher priority. So, if I can patch it for now and help keep it from stinking up the cabin, that's sufficient. We're day sailors, MAYBE weekenders, not cruisers, so we won't be using the holding tank much anyway. I'll be getting the boat pumped out every time we return to the slip and the tank is used.

The tank is in a fairly small space, so I only have a 9 gallon tank right now. I'll have to look a the other tanks, too. I'll also compare them against composting heads and other options. If I'm going to spend the money, I may as well see what else will work. But that's something to research in a few months.
9 Gallon is really small, likely just there to satisfy the requirement to have one. With kids I would think that may only last a day or two! I think I might look into a composter, they would not be nearly as affected by a flushed down army man, or other not to be flushed item! If not at least look into a larger tank if there is any space to steal from.
 

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Discussion Starter · #20 ·
Paul,
I agree, 9 gallons is very small. When we brought the boat up from MD to NJ, it was just two guys. We overnighted aboard one night, and then used the marina the other two days, and we did our best to limit our use of the facilities onboard. It was still pretty full by the time we were done the 3-day trip. I'd like to take her out for a weekend with my boys, so with 3 or 4 aboard, that 9 gallons could fill up very quickly, even if we overnight at a marina. I have been toying with the idea of getting a bigger tank (assuming I stick with a traditional head), but the space where it fits isn't all that big.
 
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