I thought I'd add an update to my earlier post on this thread...
Having previously unplumbed the LectraSan system last summer, I'm finally taking time to tackle the installation of a holding tank in Drifter. It was not my intention to ever be dock-based for any length of time. But since this is what happened to some extent, I really haven't had the need for a holding tank... I simply use the facilities in the marina. It's time to get this game plan back on track and "Get out of Dodge", as Dave Kall keeps prodding.
As you all know, current regulations are quickly moving toward "zero discharge" in most coastal areas. Although my LectraSan and Lavac combination provided a suitable solution in the past, it appears the only safe bet today is a system that incorporates a holding tank.
After finally removing the LectraSan system, I revelled in the recovery of useful storage in the bathroom cabinet. This presented me with the challenge of finding some place else to install the new holding tank without sacrificing my newly reclaimed and easily accessible storage. I've seen holdings tanks installed in many places in the W32, but most of them result in the loss of a good deal of space that could otherwise have been used for storage of varying degrees of convenience. I was hoping to find a location that would otherwise be TOTALLY unused. It finally occurred to me that perhaps the only place meeting that requirement was under the head itself.
With some reservation, I began cutting the section underneath the head, in order to gain access to the area beneath the raised layup. To my surprise, the floor beneath the head was over an inch thick, comprised a sheet of plywood sandwiched between two layers of fibreglass matting. Considering that the dimensions of this floor is only about 14" x 22", that's about the best description I can imagine for the term "a brick sh_t house".
Upon viewing the surface beneath, I considered using the hull as the bottom and one side of the tank, laying up the rest of the with cloth and epoxy. I decided not to do so, in case I ever needed to gain access to the bulkhead for repair, and decided to fabricate the tank using West System Epoxy over 1/2" plywood. The exposed area provided a flat surface only 8" x 13". From that point, there was a steep slope toward the Port side and a shallow slope toward the bow. Using 1/2" exterior plywood, I shaped the bottom and sides to maximise the available space. Of course, not one side had a single90 degree angle anywhere (except for the top)!
Because of the steeply sloped sides, using an off-the-shelf rectangular poly tank, I could only have incorporated about 6 gallons. By custom fitting the tank, I managed to increase the capacity to 14 gallons! It was a bit more effort, but we'll worth it to me. Some would argue that 14 gallons would be insufficient capacity for a holding tank. But for a solo sailor, I'm sure it will be plenty.
The following photo shows the available area with the 1"+ floor section removed. Notice the 2" cleat attached to the bulkhead and the sloping sides.
The tank sides are cut with no 90 degree angles anywhere! At this point, the box is taller than it will end up. I eventually trimmed it a couple of inches above the height of the previous floor. Then I'll build a facade around the tank, providing a platform for the head. Since the Lavac is a little shorter than most marine heads, this actually places the head at a more comfortable height, while providing greater tank capacity.
Epoxy and glass cloth are applied inside and out for strength and water-
proofing. Cleats are added so the surfaces will never touch the bottom.
The project is not quite finished, as I had a slight altercation with my table saw and need a little time to heal, before continuing. (All in the course of progress.)
I'll provide more details as I near completion and finish with the plumbing, etc.
The best aspect is that I will meet the newer regulations for zero discharge, yet actually GAIN storage space due to the removal of the LectraSan. Hopefully, someone else can gain from this idea. (The tank fabrication, that is... not the fingernail trimming.)
Jack Webb