Matt,

Have you thought about this scenario? You accidentally leave the propane on
when you leave the boat, or someone else turns it on after you leave. There
is a really small leak, but in three weeks a fair amount of propane collects
down in the bilge.

You come back and open the boat up just like always, and reach down and turn
on your sniffer. The small spark from the switch closing ignites the propane
(BOOM).

The only way I can see to avoid this scenario is to have explosion proof switches,
(But then your bilge pump auto switch might set it off), or to have an always on
bilge vent system that runs from solar power. An alternative would be to have a
bilge vent system with the fan mounted really high vaccuming out a tube that goes
down to the bilge. The switch for the fan would also be mounted _really_ high so
that it would be above any potentially explosive fumes from the bilge. Of course,
your bilge pump auto-switch might still set it off while you are gone.

I'd prefer that my boat not blow up at all, but if it does, I'd really like to not
be standing in it at the time ;-)

YMMV,

Don W.

wrote:
Ari

Glad to hear all ended well.

My advice would be to get it out of the bilge. These things do no
tlike getting wet.

On my boat, the sniffer is just above the cabin sole in the face of one
fo the settees. It is wired to bypass the master switch but is not
always on. It has its own switch right next to the master switch.
Procedure is to turn on the sniffer first. It will beep while it warms
up (10 - 20 seconds) and then go silent once its warmed up and no gas
is detected. I like this setup as it tests the sniffer every time you
get on the boat. I spent the first season with this boat diligently
turning on the sniffer and being happy at "silence" every time. Next
spring I found out that the sniffer had been disconnected the whole
previous season.

Matt

Very good stuff quoted below. Listen to Larry.
Now if the boat manufacturers would only build their systems this way.

Larry W4CSC wrote:

Marley wrote in
:


No fuse?




Of course not! Boat installations of small-wired electronics is hardly
ever fused at a safe level for the size of the wiring involved. It's wired
to that 15 or 20A cheap thermal breaker that also drives the cabin lights,
those tiny wires to the compass light, #22 wire to the GPS and those #22
wires to those GOD AWFUL little plastic Hella fans with NO INTAKE GUARDS in
the cabin!

You want us to put in a LITTLE FUSE PANEL to protect all those little
wires?! What a concept!

I'm confused about the remarks of the STUPID bilge pump switch. The bilge
was full of water or smoke from the burning wiring?? Or did the stupidity
of the bilge pump actually having an OFF position submerge this gas sensor,
causing it to short out?? The CORRECT wiring procedure for the bilge
pumps, ALL the bilge pumps, is a separate circuit STRAIGHT to the battery
banks for each bilge pump. + battery with fuse within 6" of battery
terminal (inline ok) to float switch to bilge pump to - battery terminal.
If you so desire, the float switch may have a manual override switch in
parallel with it in case it gets clogged or disabled, a good use for this
stupid bilge pump switch. The fuse rating of EACH bilge pump would be
protecting the SMALLEST wires, those little damned things to the plastic
floatswitch or pump motor, in the circuit. I like to run the bilge pump
under a load (pumping water unobstructed) while I measure its current. If
it draws 1.3A under load, I want the next-higher-size fuse of twice that
current ONLY IF THE WIRES CAN HANDLE IT. If the bilge pump motor becomes
stalled with trash, I want the fuse to blow....instead of the bilge pump
motor to just sit stalled and fry, possibly melting or catching fire. The
bilge pump draws a lot of current starting under load, so use slow-blow
fuses to prevent nuisance blows, rendering it useless. I find a STALLED
Rule pump draws plenty more current to blow a double-the-normal-current
fuse to save the pump. If it shorts, the fuse blows. If it stalls, the
fuse blows saving the pump for a cleanout. No fire, no smoke...safe.
Because EACH bilge pump has its OWN circuit/floatswitch/fuse, blowing one
fuse doesn't disable all the pumps at once. Life goes on.

There is the neatest little piezoelectric nag alarm at Radio Shack. It's a
round, black plastic, 12V, nauseatingly antagonizing, pulsating beeper
noise maker. Mount it through the plastic somewhere in the cockpit that
will aggravate any sleepers below, plus anyone walking by on the dock.
Connect this alarm (ours also has a bright red pilot light in parallel with
it with a little sign saying what it means)....Connect this alarm/light
combo ACROSS the fuse! + side of the beeper to the battery side of the
fuse....- side of the beeper to the floatswitch side of the fuse. It will
not beep or light UNTIL THE FUSE BLOWS, alarming you that that something is
wrong with THAT bilge pump. Compared to a sunken ketch, cost of this
little beeper alarm is MINIMAL!

There...now NOONE can turn off the bilge pumps unless they unplug the fuse
manually. The fuse protect the circuit from losing its "magic smoke" which
makes all electrical/electronic gadgets run. It even protects the bilge
pump from the trash that got in and locked the pump up so it won't fry the
pump motor! When the trash...or a short....or a bad (shorted only) motor
blows the fuse, the alarm sounds that something is wrong with THIS bilge
pump, making troubleshooting at our earliest possible moment
happen...before the water comes up over the teak and holly. Much better!

Add another float switch on another separate, straight-to-battery-like-the-
bilge-pump circuit. This float switch is 6" higher than the one that turns
on the pump and should NEVER activate. If it does, it powers a Radio Shack
alarm system 130db reentrant horn alarm that looks like a PA speaker up on
the mast pointed down the dock so NOONE SLEEPS AS YOUR BOAT SINKS! As it
has no OFF switch, they'll have to call you IMMEDIATELY to shut the damned
thing up before the boat sinks.....(c;

Flooding in the bilge is never funny!

Please REWIRE every small electrical and electronic load in this boat in as
many separate little fuse panels as is necessary so that each small load
has its OWN properly-fused circuit. Hook the fuse panels to the breaker
panel in the boat with wire appropriate to the size of the breaker. 20A
breaker, use #12 or #10. 15A breaker, use #12 or #14....no smaller.
Glowing wires like you've already witnessed can burn that plastic/epoxy
beauty right to the waterline!

Don W wrote in
:

Very good stuff quoted below. Listen to Larry.
Now if the boat manufacturers would only build their systems this way.


The only way to make that happen is if someone, like CG or FTC FORCES them
to make it happen. I always get a kick out of the "AYBC Standards"...or
course, controlled by the MANUFACTURERS.

Why does the FTC get so heated up about a little kid's car seat, for the
Ford Exploder which flips over automatically.....when they could care less
about the BOAT the kid slept in last night??

Don

I appreciate the scenario you describe. My on/off switch for the
sniffer is located in a sail locker accessible only form the cockpit
and is always turned on before anything else. It is located higher
than the bottom of the companionway which is is no way air tight. The
cocckpit drain exits the transom above the waterline.

There are no guarantees in life but the system as it currently stands
is good for most scenarios.

Cheers

Matt