Fire and Water

This afternoon I got a chance to inspect the sail locker section of the V berth area to investigate the cause of the recent electrical fire.  The opportunity came when all of the bedding was removed to take to the laundry along with the rest of our other items to be cleaned.

The wiring that was burned to a crisp was not a single ground wire, but a pair of wires, one in red insulation, one in black, housed in a black sheath.  I traced the wire through the sides of the port sail locker, across to the starboard sail locker and to the windlass battery.

Damaged battery.  Note thin red and black wires that led to the main panel.

The windlass battery was wired up as I remembered: heavy cabling to the windlass about 10 ft away, and the thinner red and black wires passing from the terminals of the windlass battery back through the sail lockers to the main panel area next to the navigation table.

The drain on the windlass battery had been severe enough to completely melt the negative post, which ran across the top of the battery as a silver streak.  The negative wires to the battery were free because there was no longer a negative post!

The heavy cables between the battery and the windlass had not been damaged.

Note obliterated negative post.

In the port sail locker area I found the demarcation between undamaged wiring (from there to the battery) and damaged wiring (from there to the main panel).  It appears that at that point the positive wire contacted the negative wire creating an open circuit from the battery to the negative bus.  The way the wiring was set up there was no defense against this - no fuse or breaker.  And my turning off the main switch would have done no good since the wiring to the windlass battery was beyond the switch.  The electrical fire ran its course and stopped when the earth wire disintegrated.

Just as well.  It seems to me that had the battery casing been breached one spark on the hydrogen gas would have caused an explosion.  It is highly unlikely that I would have been able to work my way through the choking fumes of sulfuric acid to find the seat of the fire.  Even had I managed to find the site it is unlikely that the fire extinguisher would have coped, given that the paint, then sails, then fiberglass itself would have burned.  Brenda and I would have made it because the Zodiac was in the water and there would have been time to deploy the life raft, but the boat would have been lost.

Section of wire showing problem area.

I told Brenda that we were two lucky puppies and she agreed.

Jak Mang has told me about fuses on the positive posts of batteries, something that I had not been aware of.  Arnold wrote that "autos us high-current fusible links and Maxi fuses to prevent catastrophic battery meltdowns."  I will look to install these fuses in all six of the boat batteries.

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This morning I plumbed both of Pachuca's water tanks.

We began our cruise with 140 liters of water in each tank and 20 liters of water in our portable containers, which we use for bathing and clothes washing.  We picked up 40 liters of water in San Evaristo and another 40 liters of water in Agua Verde.  40 liters of this went into our starboard (galley) tank and the other 40 we kept in the portable containers for personal and clothes washing.

At the end of the cruise we had 90 liters in the port tank, 63 liters in the starboard tank, and 6 liters in the portable containers.  The bottom line is that Brenda and I used 10.5 liters (2.77 gallons) of water per day.  Had we not used fresh water for bathing and clothes washing our consumption would have been 8 liters (2.1 gallons) per day.

I will supply our fuel consumption numbers after I have refilled the boat's diesel tanks.