"POO TANK"

The holding tank on Mintaka was a flexible bladder tucked away in an inaccessible spot.  It was too small, impossible to tell how full, an inefficient use of space, and with a complex system of valves.

Plumbing chase with most of the plumbing removed

So, never one to avoid big projects, I converted a portion of a plumbing chase -- a chase is a space dedicated to some utility, such as plumbing or wiring -- to an integral, fiberglass holding tank.  This new tank is above the water line, so it will self-drain, removing the need for a pump.  It is also much larger, uses the space more efficiently, and requires only one valve (and that in a better location).  The catch is that I had to reroute all the plumbing that was in that chase, including a couple of deck-fills, and then seal the inside of the chase with multiple layers of fiberglass.  Of course, this being a boat project, the geometry and location of the chase would do the Marquis de Sade proud.  It was only twelve inches wide (fore and aft), but as deep (i.e. to the side of the hull) as I could reach.  Applying four layers of fiberglass in there, together with brutally awkward sanding, all while wearing a "bunny suit" and respirator, was not fun.  

Sealing old holes in one of the bulkheads

Sealing the old vent and deck-fill holes

Sure gets hot in that suit

All glassed in, needing the base and the inboard panel

Base with drain

Drain underneath the tank base

Closing in the tank from the outside, while effectively glassing the inside, posed an interesting problem.  The solution was to cut out an access portal in the final, inboard panel, so that I could reach through to glass it in on the inside, and then to glass in a plug for the portal.  Easier said than done.  I cut a rectangular plug out of the final panel, creating a frame with a portal that had an inward facing bevel.  Then I glassed the frame on the inside as well as the bevels, then mated the frame and the plug, using epoxy "bog" along the edges of the plug to make it a perfect fit.  Only then did I glass the frame onto the tank, followed by the plug.  I put some temporary handles on the plug so that I could turn it sideways, insert it through the access portal, then pull it outward against the bevel while I glassed over the seams.  I’m no stranger to hard, nasty projects, but this one rated right up there.  If I had known how heinous it would be, I wouldn’t have started.

Cutting the bevels in the inboard panel

Inboard panel glassed in place ...

... and with the plug being installed

The old system had two through-hull fittings, one for direct discharge from the head overboard.  The other, for pumping out the holding tank.  Both were old, corroded and very hard to turn.  The first of those was under the head-compartment sink.  With the new system design, we were able to eliminate that fitting entirely, greatly improving use of that space.  The latter was in an awkward spot in the plumbing chase, not optimal for the new tank, so I removed it, and installed a new fitting in a better spot, also improving the use of that space.  Of course, removing those two through-hull fittings left two gaping holes in the hull.  An hour or so with an angle grinder, however, created broad concavities instead of just holes, and repeated applications of fiberglass over the next few days filled them inside and out.  The beauty of a fiberglass boat is that it can be sliced and diced and glued back together as good as new.

One less through-hull

Ground out, ready for glass

Hole gone

The repairs to the holes are just about ready for paint, and a couple of pieces of sanitation hose still need to go in, but this project is largely done.  Actually, that’s only one half of the overall head renovation project, but that’s another post.