Re: On board fires

[VBra676539@aol.com]

Ray,
	Most fires that I have ever heard of (half a dozen maybe?) were 
electrically driven and extinguished without resorting to chemicals.  Once 
the breaker on whichever system pops or is popped, or the fuse snaps, the 
thing just smolders to a halt.  Burning insulation and the like have not been 
a problem, although attention to detail when making cushions and the like is 
required.  Fire proof or at least fire resistant foams and upholstery fabrics 
are available and should be stipulated.  Of course, that's why you carry a 
fire extinguisher, but oh what a mess!
	It goes without saying that every single electrical component must be 
fused or breakered.  Every single light, or light network (interior lighting, 
for instance, is usually wired from one switch on a distribution panel, and 
fused as one thing).  Scrubber, spares, external lights, thrusters and so on, 
need circuit protection, as well as breakers to rack the battery banks in and 
out depending on need.  You simply cannot wire these things like the family 
cabin cruiser--jumping OFF is not an option, and jumping OUT, although 
possible, is not anyone's idea of a way to finish off a pleasant Sunday 
outing.  For example, my Kitteredge has 5 main breakers in the main power 
panel:  36VDC port, 12VDC port, 36VDC starboard, 12VDC starboard, and Main 
Propulsion 36VDC.  My distribution panel has copper bus bars (thank you HBOI) 
and a series of switches each with a bayonet mounted fuse to power all the 
bits and pieces.  Horizontal and vertical thrusters, and main motor controls 
are in a small box on a 6' cable, but they only operate the reversing relays, 
main motor relays, potentiometer for the speed control and the like so no 
heavy current to worry about.
	The BIBBS is just a built-in-breathing-system:  as basic as you like. 
 I use a standard brass regulator block, keep a single hose regulator (with 
extended hose) hooked up, pressurized and ready (part of the pre-dive check 
off) and a scuba mask to enclose eyes and nose.  The mask can be cleared of 
smoke in the same way that you would clear it of water while diving, and 
serves very well.
	Exhalation will pressurize the boat to some extent, although one 
expects not to waste a bunch of time with the boat full of smoke and fumes.  
ABS and all the other agencies require a means to equalize the boat's 
internal pressure while surfacing.  A ball valve hull stop inside with a 
short tube outside will do the trick, mounted high and relieving somewhere 
out of the water when surfaced (to keep a vacuum on the boat from siphoning 
water in, of course).
	Truth be told, I hadn't even thought of this as particularly 
interesting until you asked.  It was such a common deal, being part of the 
certification for any commercial sub, but of course it is interesting, and 
hugely important.  It doesn't take much smoke to overwhelm someone sitting in 
an oversized trash can with no alternative but the atmosphere he brung with 
him!
Regards,
Vance