Thanks for the question -- it's given me a chance to put a variety of
thoughts on paper, as we're still designing the plumbing for Fintry.
Thoughts, in no particular order:
1) Assuming your tanks are below the cabin sole, put the tank vents
together so they run into the galley sink. This protects them from
salt and lets one watcher see instantly when one is full. This need
not be obtrusive, just a little set of upside down "J"s above the
level of the counter -- not below, as it could siphon back.
2) Run one deck fill into a manifold (but see #3).
(deckfill) (shutoff) (draw to pumps) (manifold with one valve
for each tank)
This allows you to fill all the tanks at once. You can pipe the
watermaker into the (draw from pumps) space as well.
3) We had a watermaker (separate subject) and therefore never took
water where it might be marginal (In three years we took it only in
USA, Papeete, New Zealand, Singapore, and the Med). The watermaker
likes to run, so use it. Without a watermaker, plan on taking
marginal water. Perhaps separate deck fills, perhaps separate systems
below for showers and drinking, etc. There are a lot of places where
you can get water that is fine for washing but marginal for drinking,
some of them surprising -- the Health Officer for the Darwin-Ambon
Race advised us all not to use Darwin water -- significant risk of
Giardia.
4) I think Glenn's double clamping is overkill -- double clamp
seawater lines -- they can sink your boat -- but the worst case on a
freshwater line is that the pump empties one tank. Clamp failures are
very rare.
5) Put a foot pump in line with the galley cold water line for the
times when the pressure system is down. If you don't have a
watermaker, put one at every cold water faucet and turn off the
pressure when consumption is an issue. The foot pump can draw right
through a diaphragm pressure pump and vice versa.
6) Put a hot and cold hose in the cockpit.
7) If you'll spend a lot of time at a dock in non-freezing weather,
put in a pressure regulator and shore hose connection.
8) I like the Jabsco diaphragm pumps -- they're simple, parts are
replaceable, and the same frame and motor is available as a bilge and
shower sump pump, allowing you to carry fewer spares (the bilge pump
is geared for low pressure, high volume, the water pump for high/low).
Their pressure switches are problematic, however. IIRC they are
Microswitches with a DC rating of around 1/2A, while the pump draws
3-6A (depends on voltage). You can pipe in a better switch if you
want to pay for it, or buy lots of spares (IIRC a six month life in
liveaboard use). Note that the switch is available by itself for less
than US$10 or as the assembly for much more.
9) I think Glenn is overkilling with two pumps, both on line all the
time. I'd prefer two pumps with two way valves on both sides so you
can manually switch them over. I like to know when things fail, which
you might not with Glenn's arrangement.
10) Schedule 80 PVC (gray) is essentially bullet proof and a lot
cheaper than metal. You might even use Scd 40 (white) if it's
protected from feet and other ugly things. Neither are permitted for
hot water ashore and if you use engine heat for hot water it will be
hotter than shore water, so use CPVC for hot (I've never seen Schedule
80 CPVC and Dogpile gives no results for a search).
11) I'm not sure I like an LPG water heater. Safety issues are real.
It's fairly easy to enforce turning the LPG supply on and off for the
galley stove, but an on-demand water heater would require more
discipline. Also, in many places, diesel is easy to get and LPG is a
PITA. On Swee****er we had an electric tank heater with two coils, so
running either the engine or the genset heated water (I hated the
thought of running the genset and using most of its electrical output
to heat water). If you don't have a genset, though, you have limited
choices when shore power isn't available. Run the main to heat
water????
12) Without a watermaker, Lew's hot-water-runs-back-to-the-tank system
makes a lot of sense.
13) On Swee****er in the tropics, from Panama to Fiji, three of us
used 15 gallons of water a day with daily showers. Enough, but not
profligate, was the attitude. For two weeks in the Societies, with
four guests (including two long blonde hair teenagers) consumption
went up to 75 gallons per day with a lot of swimming, diving, etc.
14) Put a filter before the pump. Pumps don't like the sand in some
shore water.
15) When a tank runs dry and you need to switch tanks, it's helpful if
you have a valve teed into the pump discharge that runs into an open
sump or the bilge -- it makes it much easier for the pump to get its
prime from the new tank if it's running against zero back pressure.
(Switch tanks, open valve, run pump, pump primes, close valve).
Without this, the pump is working against all the air in the system
including the accumulator and takes much longer to prime.
16) Use single outlet faucets throughout. If you use engine heat to
heat water, it will be much hotter (up to 205F) than people are
accustomed to ashore. You might even put in a thermostatic mixer
downstream from the hot water tank to reduce the temperature. These
are standard on domestic tankless boiler systems, so you'll find one
at Home Depot.
17) If you have a watermaker, pay attention to the fact that many of
them do not like chlorine -- you need to be able to backflush the unit
with its own output that has not been contaminated by shore water
(there are several ways around this, including simply waiting, but you
have to pay attention).
18) If you're going to winter in cold climates, don't run water lines
against the hull above the waterline.
19) If the boat will spend the winter on the hard, make winterizing
easy.
20) Put a port in the top of each tank above the deepest point, so you
can use a calibrated stick. Keep track of consumption.
21) On smaller boats, consider using a header tank for pressure and
pumping it up once a day. We had this on Clarissa Carver, a 40'
schooner, where the tank was just under the main deck. Pressure was
modest but usable and it avoided all the nuisance of freshwater pumps,
particularly the pressure switch. Fintry also has this system now (55
gallons on the upper deck) and I'm considering modifying it for future
use.
22) Arrange your system so that if the working tank runs dry from a
leak and the watermaker fails that you always have enough water left
to provide a gallon per person per day for the longest contemplated
passage. You can live on less, of course, but you won't like it.
Jim Woodward
www.mvfintry.com
(Aluminumhullsailor) wrote in message . com...
Listers,
I have been working on a fresh water system to install on a 45 foot
cruising monohull sailboat. Does anyone know of any online schematics
or idea lists that may provide me with another line of thought? Any
books you have found helpful would be a good tip also? I will post my
schematic in a few days for comments.
D