Seems we're not 32 anymore.
I'm continually astonished to rediscover that almost daily.
A foundational problem is this instance is that of a '70's boat never
envisioned to need MSD, backfitted with a tank that entirely fills the
only reasonably avail space without extensive mod, which is still only
1/2 the capacity of present-day practice, i.e. 45 USG/37' LOA
motorsailer.
A 45 gal tank should be more than adequate for a 37' boat. In fact, it's
about 50% larger than what most OEMs are installing today on boats that
size.
People have highly unrealistic ideas when it comes to waste holding
capacity...they expect a tank to hold enough waste from a family of 4 to
be able remain continuously aboard for 2-4 weeks between
pumpouts...not realizing that the average volume including flush water
for a family of 4 is 10 gal/DAY. Even just a cruising or live-aboard
couple would need tankage big enough to turn their vessel into a
floating honey barge to stay aboard continuously more than about a week.
Yes, austenitic SS has pitted in MSD use since we first though it'd
work well in '76. (You should've seen the other & bigger boo-boos we
made with early commerical MSD's.)
I have seen them...recirculating systems is only one example.
We can get it fabbed for free,
though, & flush & repassivate it view she will only be afloat 3 mos/yr
for the next decade.
Used only 3 mos/year, or used year-round...10 years is still the average
lifespan of any metal waste tank. Flushing and repassivating doesn't
extend it much if any...metal WATER tanks rarely survive more than 20
years before springing a leak somewhere.
Good news is she has a free berth alongside a commercial cargo terminal
that has great heads inside. :-)
What is the make/model age of the heads on the boat? If still
original--or even more than a few years old--they may or may not be
worth servicing...if, in fact, any parts or service kits are still
available. How many heads?
Another issue/question arose during this minor Chinese firedrill:
urethane foam.
Don't do it...foaming in tanks is neither recommended nor necessary. For
one thing, federal law requires that there be some means of determining
when a waste tank is at least 3/4 full (this is supposed to prevent
accidental overflows out the tank vent). If the level in the tank cannot
be determined by visual inspection--which foaming it in would make
impossible, a gauge is required.
However, foamed in or not, if the location of the tank makes it so
inaccessible that visual inspection becomes so impractical as to be
impossible, you'll still have to install a gauge.
Tanks rarely bounce, even in heavy seas...but they can slide if not
secured. In most cases, all that's needed is a non-skid mat under
it...Walmart, K-Mart etc sell some rubber kitchen shelf liner by the
roll that's perfect for this application (and in the galley...NOTHING
moves on it...I've seen an otherwise unsecured microwave stay put on a
boat heeled 20 degrees) and straps (lawn chair webbing works well). If
necessary or desired, you can also brace the corners with wood strips
epoxied to the hull. So secured, the tank will not move and remains
accessible for service and visual inspection.
Were she mine, I'd consider a more extensive mod to fit more tankage of
less unusual dimensions.
Were she mine (unless she's on the Great Lakes or other inland "no
discharge" waters--in which case, you can't legally use the macerator),
I'd put a Type I MSD on it--specifically a Lectra/San--backed up by a
small tank for use only if/when The discharge of treated waste is legal
in at least 90% of US coastal waters, and is a far more ecologically
sound solution to onboard waste management than a holding tank. Why
store waste aboard if each flush can legally go overboard without harm
to the environment?
--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/store/custo...0&cat=6&page=1