H 33 Holding Tank Installation

It is probably safe to say that the great majority of the original bladder holding tanks
installed in the H33 are well past their prime. When I bought my H33 about 18 months
ago, the bladder had been removed and there was no holding tank at all. I installed the
plumbing detailed below shortly after buying the boat and it has served with no or very few
problems. Hope that this helps other H33 owners.

Schematic (Figure 1)

The schematic shows the general plumbing routing. The arrangement allows for discharge
either into the top of the tank for holding or through a vacuum breaker loop directly
overboard. Once held, waste can either be discharged overboard by gravity or pumped
out through the original pumpout fitting.

Hunter 33 Holding Tank Schematic

Upstream Y Valve (Figures 2 and 3)

Figure 2 shows the forward y valve mounted on the fiberglas portion of the bulkhead
between head and cockpit starboard locker. It routes the waste either directly overboard
after passing through a vacuum breaker loop (Figure 3) or into the holding tank. Access
to this y valve is awkward directly through the cockpit locker but a 4” screw in deck plate
in the fiberglas bulkhead, allows easy access from the head. This deck plate port does not
show in Figure 2 as it is hidden behind the hw heater. Access to it and thus the Y valve is
obtained by removing the upper drawer to the vanity

Upstream Y Valve

Vacuum Breaker Loop Fitting

Holding Tank and Holding Tank Y Valve Mounting (Fig 4
and 5)

A 13 gallon polyethylene tank, (24 L X10W X14 H, Todd, West Marine Model
486738 is fitted into the narrow space just below the starboard deck between the hull and
the starboard wall of the cockpit T. The top of the tank is as close as possible to the
toerail bolts. The tank is jammed aft as far as it will go into the space between the hull and
the starboard wall of the Cockpit T, effectively restraining the top of the tank. The lower
outside edge of the tank is supported by a piece of properly chamfered 2x4 material
fastened to the inside of the hull with 5200 adhesive sealant. The tank was dry fitted into
the space, the bottom marked and then the chamfered 2x4 installed and allowed to set
several days before final tank installation. A removable stop on the 2x4 at the forward end
of the tank keeps the tank from moving forward but still allows future removal of the tank
for access to the affected toe rail bolts. A second piece of 2x4 material screwed into the
tank supporting 2x4 and extending forward serves as mounting base for the holding tank
Y valve. The existing pumpout fitting in the starboard deck and the original vent are
straightforward routings from this tank location. Routing from the head and to the through
hull are also clean. All the hoses are near or directly against the hull, thus impinging very
little on the usable cockpit locker space. Since the bottom of the tank is perhaps 24” above
the through hull the tank is quickly emptied by gravity with no need for the old
diaphragm pump installed originally with the original bladder.

Holding Tank and Downstream Y Valve

Holding Tank Looking Aft