Tuesday, June 19, 2012

New Tank, New Problem
By Michael

We arrived in Avalon, on Catalina Island,
yesterday. Like any tourist trap, there is
no shortage of pidgeons and ice cream.
When the new holding tank arrived at the marina office via UPS, it was a heavy monster. I took the 28-gallon beauty out of the box and showed Windy just how thick the polyethylene was.  Surely we were one installation away from an odor-free vessel.

Not long after I installed the new tank we began to notice the smell.
“Maybe it is residual from the old tank.”

A day passed.
“Are you sure you cleaned up really well from the old tank?”

A week passed.
“Did you forget to tighten a hose clamp?”

We hadn’t needlessly replaced the old broken tank—it was cracked and the flanges where two of the fittings attached were leaking—but could we really have made things worse?
Then the smell became unbearable. What the heck?

I checked and rechecked everything, again. I bought some microbe pellets at West Marine that are supposed to naturally keep odor in check. Things seemed to get worse and each of us, in turn, began to miss our old leaky tank.
Then I found the problem.

Our brand new, nearly $300 Todd tank was defective. The welded polyethylene flange at the top of the tank, threaded for the inspection port, was leaking. I called Todd. They seem like nice folks, but they were not keen on discussing tank problems over the phone, they wouldn’t even hear me out. I was told to take pictures of the problem and send them a description and they’d get back to me within five business days. Nonsense. [Ed: note that a previous version of this post indicated that I talked to Todd's Mexico and Central American representatives, E&P Marine, but that was incorrect, I spoke with Todd customer service directly.]
Del Viento on her mooring, the
iconic "casino" beyond.
So I turned to my friends at Google and learned everything there is to know about repairing polyethylene. The sealants we commonly use aboard don’t work on polyethylene, not even the tenacious polyurethanes like 3M’s 5200. Learning how to seal and repair the material would come in handy as everything is made with the stuff these days, from our kayak to our new Portland Pudgy.

It turns out there are several different approaches, but I went with Gougeon Brothers’ G/flex epoxy. So long as the surface is prepared correctly, the stuff sticks to and seals polyethylene very well. I abraded the crevice with a Dremel, cleaned it with rubbing alcohol, heat treated it with a butane torch, and then mixed and applied the epoxy. A couple weeks later, I am happy to report that the bond is strong and the head odor is completely gone.
While I’m on the subject, I’ll pass along a tip we learned from someone before heading out: oil and vinegar are your toilet’s friends. We keep a spray bottle of oil and vinegar at hand and we shake it up and give a couple squirts with each flush. The vinegar is a sanitizer that keeps hoses from calcifying and the oil helps lubricate the pump. Use a cheap vegetable oil and plain white vinegar, anything fancier and you risk developing an unwanted negative association that will put a damper on your salad cravings.

The West System G/flex epoxy is yellow when cured.

We took the girls to the Ocean Institute before leaving Dana Point.
The place is pretty cool and dedicated to teaching folks about
marine science. The entry fee to the non-profit was $22 for the family.

The girls dissected a squid during their visit; here Eleanor is
finding and removing the beak.


  1. We had a similar problem on our CSY 33 with the holding tank- which was directly under the V berth where we slept! Add to that the gravity defying drain lines running from the head to the tank and back to the thru-hulls, we couldn't get rid of the smell.

    We ended up chucking the hole kit caboodle including a macerator pump in favor of a composting toilet. Back then the only one marketed to boats was Airhead but now there's Nature's head as well.

    HUGE improvement on many levels including NO SMELL.

    We're strictly coastal cruisers at this juncture on the Gemini 3400 Cat in Mexico, so I think we'll do the same when the head maintenance becomes untenable.

    It's good to now about the plastic epoxy, that darn sun eats up water jugs, jerry cans, and more in a as little as a season or two with no easy repair available.

  2. I didn't realize that the typical sealants won't work on polyethylene either. Thanks for tip and for the detail on the epoxy repair. My dad's boat has a few bits and pieces that need to be repaired, so this may come in handy!

  3. Love seeing pictures of the girls! I'll make time for all your writing one day too. ;-)) hi to Windy

  4. I thought I had a problem with the seal on my holding tank letting stink out, so I did the GFlex thing too. It actually ended up being standing water in the bilge.


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