J/42 Tank leaks and Zinc survey
Ivan Getting, Kittwake, September 2007
Greetings,
Thank you to all of you for responding to my inquiry about holding tank and zinc
problems on J/42s. About a dozen were received. Below is an approximating
compilation your responses with some comments of my own added (in Itallics).
Holding Tanks
1.5” Fittings
No one else reported holding tank leaks at these fittings. One reported nylon
fittings rather than Marlon fittings. One reported gray fittings (could well be
Marlon). So far I seem to be the only one to have sewage dumped into my bilge. I
plan to replace the aft holding tank and use matching tapered pipe thread
fittings in the ports. After the forward tank let go I cannot rest easy with
those Marlon fittings in my aft tank.
Inspection (cleanout) Ports
Several people reported leaks at the water and/or holding tank inspection ports.
This results from the manufacturer having used a fairly soft, round cross
section seal (O-ring style) without providing any radial constrain for the
outside of the seal. As the cap is tightened the seal extrudes outward prior to
forming a good seal. This frustrates any further hope of making a seal. Less
torque leaks anyway. My solution, and that of several others, has been to wrap
the machine threads of the cap with Teflon thread sealant tape (or to use some
other thread sealant). The parallel threads are not designed to seal, but they
do with enough tape. Too much tape could stretch the female threaded insert, so
be careful. I tighten mine gently with a very large pair of slip-joint pliers
(Channel Lock, $35) which grip the protrusions on the edge of the cap and then
do not remove them unless necessary.
Aft Head Odors
Unpleasant odors in the cockpit were reported by several people. The aft holding
tank does emit odiferous air out its vent as material is pumped into the tank.
This can lead to an unpleasant odor in the cockpit area for a while, but it
typically dissipates rapidly and ceases when the head is no longer being pumped.
When I first noticed it I was quite concerned that the aft holding tank was
leaking. Fortunately, it was not.
My aft head produces a noxious order like rotten eggs if it has not been pumped
for as little as one day and used only for urine. We purge the exit hose with
10-15 pump strokes. The cause of this unpleasantness remains a mystery. It does
no happen with the forward head.
Zincs
Zinc life was highly variable. Offshore conditions lead to the longest zinc
life. Warm water and/or specific harbors seemed to produce the shortest zinc
lifetimes. Reports are (crudely) tabulated below:
Zinc Life (months) Number of Reports
---------
-------------------
1-2
2
2-3
2
3-4
2
4-5
1
8
1
12 -36
2
My zinc life is 2-3 month during summer cruising in the Pacific Northwest,
including Canada, and the full 8 months the boat lies unused in the marina
during the winter. The short life during the summer requires diving under the
boat to change zincs under inconvenient circumstances on longer cruises.
Fuel Tank
Two people reported having their fuel tank rot out on the bottom where it sat in
water due to poor drainage and wet residual sawdust chips left under the tank. I
sure hope this is not a common event!
I have an auxiliary bladder fuel tank which dumps into the main tank through a
valve mounted in a plate on the top surface of the main tank. This plate appears
to have installed in a completely amateur fashion with three different size
screws, a hand cut gasket, and some sealing compound. One of the screw heads,
probably a Philips head in a previous life, was striped initially. This plate
now leaks and introduces diesel fumes into the aft stateroom. Yet another repair
project awaits me.
It was good to hear from all of you. Your replies have enabled me to put some of
my J/42 problems in perspective. Thank you.
Ivan Getting
KITTIWAKE
J/42, hull no. 74, 2006