Wednesday, March 30, 2016

Hold It!

Here we go again on one of the least-pleasant things to work on in a boat. Ever since I had the black water lines replaced in Deltaville, I've had issues with these systems.  A few things were obviously broken (like the toilet seat and bilge pump hose) but others were random leaks that we had yet to resolve.  One in particular that has been an issue was a leak at the bottom fitting of the starboard side holding tank.  If you pumped a little water into the tank it appeared to work just fine.  But once above a certain level, the pressure would cause a leak.

Figuring it was knocked loose when the hoses were replaced, we tried tightening the nut on the bottom, but that didn't fix it like it did with the other tank.  Yesterday we decided that we would loosen the fitting and see if we could reseal it without having to remove it or the whole tank. Removing the tank would require disconnecting four fittings and the tank sensor and then wrestling it out of it's perch in the locker and that would be a very time consuming process and likely break one or more of the other fittings.  We loosened up the fitting and were cleaning it up when we discovered the likely source of the leak.  The fitting actually had a small crack hiding in the threads.  In the process of wrestling the hose back off of said fitting, we made the crack worse so you can now clearly see the issue in the picture below.

The new fitting with the homemade gasket and
the old fitting with the crack.

This fitting is actually nothing more than a 1.5 inch plastic through hull fitting.  We got lucky and found a new replacement fitting at a reasonable price at Sailors Exchange in St. Augustine.  The next trick was to figure out how to install it so it would seal well without removing the tank from the boat.  But before we could do that, we needed to get the old one out of the tank.

The only access to the inside of the tank, other than the fittings, is via a cleanout access panel on the top side of the tank. With the tank installed, access to the access panel isn't easy.  I put on my best MacGyver hat to come up with a solution to remove the old through hull.  I took a scrap piece of vinyl hose that would just barely fit inside the fitting and used that to guide the fitting up to the inspection port. Tada.

The old fitting was bed in place with some sort of sealant.  Of course, applying sealant and getting the fitting back to the hole in the bottom would be a sketchy operation at best. I could see sealant all over the inside of the tank except where we needed it at the fitting. When I was looking at various fittings for plastic tanks I noticed most used gaskets.  Figuring this ought to work, I took some of our left over gasket material from the bimini project and proceeded to make a gasket for the base of the fitting. Now, if the surface isn't too uneven and I can get the clamping pressure right, we should have a seal.

Naturally, the new fitting inside diameter was just a tiny bit smaller than the old one, so I couldn't force the vinyl hose into the new one to help guide it back into position.  Channeling my inner MacGyver one more time, I decided to snake a piece of scrap electrical wire through the vinyl tube so I had a line that ran from the access panel down through the hole in the bottom of the tank.  I slid the fitting over the wire and dropped it into position, guiding it with the wire.  The fitting slid right into place.  Viola.

Knowing that over-tightening a gasket can be just as bad as under-tightening one, I threaded the nut on the end of the fitting and tightened it only hand tight.  We decided that the hose was actually an inch too long and cut it down for a better fit that would put less strain on the fitting.  I slid the hose onto the fitting, tightened up the two hose clamps to hold it in place and we were ready to test the repair.

New fitting installed.

We fill the tank with about two inches of water.  It looks good at first, but eventually a small drip is seen at the fitting.  I use the wrench to give the nut on the fitting a quarter turn and then wipe up the drip.  This appears to have resolved the leak.  We fill the tank to the top and check again.  Still no leak. After letting the water sit in the tank for over four hours, not a drip of water was found. Yay!

We may finally have all the holding tank issues resolved.  I guess only time will tell.


  1. I feel for you. Oh, how I feel for you. Changed the head and hoses last summer....I have a very weak

    1. It wasn't all that bad. Since we knew they had been leaking we hadn't been using them. Other than the minimal amount of "dried on compost", everything was relatively clean...for that sort of system anyway. Now, discovering the leaks while on passage a couple of years ago...and the resulting mess in the bilge...ewww.