Plumbing, Head, Part 5, Holding Tank Installation

The holding tank, fully installed
If you have read my multi-part article on the work I did in the large, aft locker underneath the V-berth, then you will know that I did almost all of this work for one purpose - creating an appropriate place for securing the new holding tank for the new plumbing system on Oystercatcher, my Ericson 25. You will also know that at the same time I sought to maximize the usable space in this large locker by creating shelves and partitions that would break up this space into smaller, more functional areas. Now that I had completed all of this work, and now that I had completed much of the work for the replumbing of the head, I now needed to install the holding tank. The steps I took to complete this task are the subject of this posting.
You'll remember that my plan called for securing the tank by means of galvanized straps.
I noticed right away that these pieces of metal could cause some problems in terms of chafing the plastic of the tank. Therefore, I purchased some small sheets of gasket material.
These I would cut to size.
I also needed to do everything I could to soften the sharp edges of the metal where I had cut it to size. I used an angle grinder for this. It was much more effective than the Dremel.
There were also two unrelated side projects that I needed to complete before I put all the pieces together for this holding tank. I had earlier installed a new bronze transducer in this space, Now I needed to secure the conduit for the transducer cable to the adjacent wooden cleat. I used my Milwaukee Tools right angle attachment to drill the holes for the hanger.
I also needed to secure the forward chainplate grounding cable to the other cleat. Again the right angle attachment was handy in the confines of this space.

Let's pause for a moment and look back at how I had dealt with this transducer cable and conduit just minutes before I completed the work I described above. This conduit had been in place when I purchased the boat in 2009. Through it ran the cable for an old, defunct instrument. I wanted to reuse this conduit, but I wanted it to be shorter in length by about a foot. My plan was to secure the conduit to the bulkhead you see pictured behind my arm.
Using my cable cutters, I removed about a foot from the end of the conduit. The string that you see is a piece of Spyder line that I used to snake the cable through the conduit.
There was a lot of excess cable, and I could not cut it short. The instructions for the transducer made it quite clear that any cutting of the cable would ruin it. Therefore, I decided to coil the excess and secure it in this space between the cleats in the V-berth.
In the picture below you can get a sense of where I would later secure the other end of the conduit - on the bulkhead in the lazarette. Notice the blue painter's tape on the cable. This was my reference mark. When I coiled up the excess in the V-berth, I had to ensure that I left enough slack in the cable on this end of the conduit. Otherwise, I would not have enough cable left over to join the cable to the GPS in the galley.

The edge of the black plastic conduit was sort of sharp. I didn't want it to damage the transducer cable. Therefore, I installed a piece of flexible conduit around the cable in the area where it entered the hard plastic conduit. You can see what I'm talking about in the picture below.
I put black electrical tape on the ends of the flexible conduit to ensure it didn't slip away from the appropriate section of the cable.
Now I needed to focus on the port and starboard partitions. I had always worked under the assumption that these would secure the holding tank laterally. Now I began to think that it would also be good to support it laterally with galvanized straps. Therefore, I needed to retrofit them into the design. This demanded that I cut some slits into the partitions - slits that would accommodate the straps. To cut these slits, I used a drill.
I also needed to cut notches on the aft end of these partitions. These notches would allow me to wrap the galvanized straps from port to starboard more easily.
The initial slits that I cut for the galvanized straps were too small. There was not enough room for me to make the turn with the strap.
This time, I used my Makita jigsaw to make the cut. No longer a slit, this was now a rectangular hole.
Back inside the boat, I put everything together without the holding tank in place, just so I could see how it was all fitting (or not fitting) together. The notches on the aft end of the partitions were definitely helping me make the turn with the galvanized strap in those areas. The rectangular holes on the forward end were now definitely large enough. The new problem was the hardware for the galvanized straps. The screws that I had installed to secure the strap to the battens on the bulkhead were now an obstruction. Specifically, the heads of these screws would likely chafe the plastic holding tank.
My solution to this problem involved Monel staples - better than stainless steel.
And it involved gasket material.
The gasket material formed padded standoffs that would protect the holding tank from the heads of the screws.
To ensure that the staples did not work themselves free of the rubbery gasket material, I applied pieces of duct tape over everything. Inelegant, I know, but a practical solution and one that would be out of sight and out of mind.
Now I could focus again on the two vertical straps.
After all the straps were ready, I put the holding tank into place.
Then I put the forward partition into place.
Next came the forward shelf . . .
and then the port and starboard partitions.
The vertical straps were first. This took some teamwork. I began by screwing one end of each strap into the lower ends of the battens. This provided each strap with an anchor point. Then a friend grabbed one strap at a time with his gloved hands and pulled that strap downward over the batten. While he held it in place, I secured it with screws.
As we did all this, we made sure that the gasket material was in place for protection against chafing.
The hardest task was the tightening and the securing of the horizontal galvanized strap. I began by taking out the slack in the strap and then securing it to the outboard sides of the partition.
Then my friend pulled inboard on the galvanized strap, and I secured each end of the strap to the forward side of the plywood partition.
We had come a long way, but our work was not done.
Now I needed to install the brackets that would secure the port and starboard partitions in place. This was a seemingly simple task, but one that was in fact tedious and time-consuming in the confines of this space.

This set-up was rock solid. The holding tank would not budge a fraction of an inch no matter how much my buddy and I pushed on it. Just for the record, in case it has not been clear all along, in the picture below we are looking aft . . .
whereas in this next picture we are looking forward. In other words, I took this picture we see below while standing in the area between the hanging locker and the head.
Believe it or not, the installation of this holding tank took the better part of a day. It was good to have a good buddy there to lend his thoughts and lend a hand. Burgers and brew were a good way to end this day.
Post Script: One year later, not long before I relaunched the boat (after this lengthy refitting), I went back and installed a Plexiglass inspection port in the forward shelf. I was troubled by the fact that I would not be able to inspect this area for the ingress of water and that it would be impossible for me to access this area in a timely manner in the event of an emergency.
This ends this posting on my installation of the new holding tank for Oystercatcher, my Ericson 25.

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