On Sun, Nov 13, 2011 at 11:48:52PM -0500, Jason Taylor wrote:
>
> Yup. Nothing like 10kwh of energy nice and low in the bilge. One wave over the
> stern with a low bridge deck or a companionway without any hatchboards in place
> will teach you a hard lesson about short circuits.
Just got through an argument in another group, where one of the posters
was loudly claiming explosions and clouds of chlorine gas that would
result from seawater across the batteries - so I made a video of what
happens when you stick 12V into seawater. Mind you, I put the contacts a
lot closer together than they would be on a flooded battery.
http://okopnik.com/origami/killer_chlorine.mp4
In essence, not much of anything happens. Sure, it's not particularly
healthy to flood a battery with salt water - particularly an FLA, where
the water can penetrate into the cells - but there won't be any short
circuits. To me, keeping the weight of the batteries up high would be a
much, *much* more dangerous thing to do in a bluewater boat.
> Batteries should be placed as low as possible but I would seriously refrain
> from putting them in the bilge.
I'd consider it OK _if_ the appropriate precautions were taken - i.e.,
if the boat was designed for it. When I first started cruising, back in
the early 90s, I met a Swedish sailor down in Ft. Pierce, FL who had
built a 78' (IIRC) aluminum boat and had a bilge full of huge truck
batteries. He had a set of HUMONGOUS switches on the bulkhead that would
either configure them all for 220VDC, which he then turned into 220PDC
with a (noisy) chopper so he could run his washer and dryer; for 120VDC
for US appliances; or a massively powerful low voltage bank (either 12
or 24, I don't recall) for all his boat needs. Of course, he had other
little luxury touches like a "garage" in his stern where he could drive
his dinghy inside and close it in behind a hydraulically-powered door...
it was quite the impressive home-built. Unfortunately, I don't recall
whether if was electrically-driven or not, but a faint echo of a memory
suggests that it wasn't. In any case, his access hatches were all high
enough that it would take a tsunami to get water up that high - and the
batteries actually sat on a grate which was positioned several inches
above the bilge floor. Quite the boat, and I *really* wish I could see
it again, now that I have the experience to truly appreciate all its
points.
--
Ben Okopnik
-=-=-=-=-=-
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