[Tuggers Issue 49 article reprint]
By Tom Blackwood, Thistle Dew 37VT46
During the Spring [2011] we took Thistle Dew to the boatyard to do a Webasto heater installation. While there, amongst other things, it became obvious it was time to change out our batteries. We had over ten years of success on our deep cycle house batteries and their little boxes were bulging. Time to go. In so doing, I removed all the house batteries from their portside engine room location and set them on the deck. Before heading over to wrangle the 8D crank battery out of the starboard side engine room location, I saw an opportunity to clean up the house battery location and do a little woodwork there. While leaning way in on the portside of the engine room working with my head nearly against the hull I hear this Whaoosh behind me. I immediately withdraw from my contorted position to look over my shoulder and to my amazement, in that short amount of time, the starboard half of the engine room was full of smoke and billowing...from somewhere. I bolted straight up the overhead hatch slapping all the AC and DC circuit breakers off, the main AC breaker off, followed by the rotary shore/ genset selector.
Without breaking pace I bailed out the starboard wheelhouse door, ran to the dock hook up and pulled the shore power cord out and ran back in through the salon and with fire extinguisher in hand, took a deep breath and went into the densely smoke filled engine room to see what I could see. Through the smoke I could see a bright, nearly molten, red wire cascading from my Northern Lights generator and it was getting redder. What is it? Where is the source? Where is the power coming from? In a flash I remembered the 8D crank battery. That ol' boy just didn't want to leave its home and was giving it its all to show its stuff. I reached up and turned the Cole Hersee selector switch to OFF and withdrew to the galley and selected OFF on that one as well. Another deep breath and back in. Through the smoke with face and fire extinguisher right up to that wire, I looked again. It was still nearly molten and red, but, the intensity was not increasing and as I held my breath a little longer I could see it was starting to dim. Exhaling on the way out, I felt a great deal of relief that I had stopped a fire just at the moment before ignition and sure conflagration.
Back in I went, surveyed the area as best I could then started to evacuate the smoke. That was close....too close. Had I been just five more steps away at the start; say up forward or in the salon, I would have lost the boat. So what happened? Short answer: don't know. Longer answer: I observed that most of the ground wires in the boat were affected; now melted or with crinkly insulation, all the way up to the back of the circuit breaker panel, especially the generator and the hot water heater. Each of those wires took out any wire that was touching it. I checked all over for any evidence of arcing and could not conclusively say I found sound evidence of same. Back to the spot in which I was working (port aft most corner of the engine room) I suspect I must have leaned against one of the house battery cables that were laying there unprotected and caused it to con- tact one of the copper water lines going to the hot water heater (that and the generator sustained the most damage). Since the grounds are tied together the juice flowed on to the generator. Because both Cole Hersee battery selectors (one in the engine room and one in the galley) were both in the BOTH position, the crank battery was then tied to the house battery cables and when shorted the battery charger (we were hooked up to shore power) decided, "hey, I've got a job to do" and kicked into full gear and was trying to charge the whole boat through the ground system. That's the best I can figure out and that's why some of the folks, for a while, called me "Sparky". I've put lots of new wire in the tug since that day, and am happy to report all is again well and after 90 some days in the yard, Thistle Dew had a very smooth 7 hour run back to her home berth.
By Tom Blackwood, Thistle Dew 37VT46
During the Spring [2011] we took Thistle Dew to the boatyard to do a Webasto heater installation. While there, amongst other things, it became obvious it was time to change out our batteries. We had over ten years of success on our deep cycle house batteries and their little boxes were bulging. Time to go. In so doing, I removed all the house batteries from their portside engine room location and set them on the deck. Before heading over to wrangle the 8D crank battery out of the starboard side engine room location, I saw an opportunity to clean up the house battery location and do a little woodwork there. While leaning way in on the portside of the engine room working with my head nearly against the hull I hear this Whaoosh behind me. I immediately withdraw from my contorted position to look over my shoulder and to my amazement, in that short amount of time, the starboard half of the engine room was full of smoke and billowing...from somewhere. I bolted straight up the overhead hatch slapping all the AC and DC circuit breakers off, the main AC breaker off, followed by the rotary shore/ genset selector.
Without breaking pace I bailed out the starboard wheelhouse door, ran to the dock hook up and pulled the shore power cord out and ran back in through the salon and with fire extinguisher in hand, took a deep breath and went into the densely smoke filled engine room to see what I could see. Through the smoke I could see a bright, nearly molten, red wire cascading from my Northern Lights generator and it was getting redder. What is it? Where is the source? Where is the power coming from? In a flash I remembered the 8D crank battery. That ol' boy just didn't want to leave its home and was giving it its all to show its stuff. I reached up and turned the Cole Hersee selector switch to OFF and withdrew to the galley and selected OFF on that one as well. Another deep breath and back in. Through the smoke with face and fire extinguisher right up to that wire, I looked again. It was still nearly molten and red, but, the intensity was not increasing and as I held my breath a little longer I could see it was starting to dim. Exhaling on the way out, I felt a great deal of relief that I had stopped a fire just at the moment before ignition and sure conflagration.
Back in I went, surveyed the area as best I could then started to evacuate the smoke. That was close....too close. Had I been just five more steps away at the start; say up forward or in the salon, I would have lost the boat. So what happened? Short answer: don't know. Longer answer: I observed that most of the ground wires in the boat were affected; now melted or with crinkly insulation, all the way up to the back of the circuit breaker panel, especially the generator and the hot water heater. Each of those wires took out any wire that was touching it. I checked all over for any evidence of arcing and could not conclusively say I found sound evidence of same. Back to the spot in which I was working (port aft most corner of the engine room) I suspect I must have leaned against one of the house battery cables that were laying there unprotected and caused it to con- tact one of the copper water lines going to the hot water heater (that and the generator sustained the most damage). Since the grounds are tied together the juice flowed on to the generator. Because both Cole Hersee battery selectors (one in the engine room and one in the galley) were both in the BOTH position, the crank battery was then tied to the house battery cables and when shorted the battery charger (we were hooked up to shore power) decided, "hey, I've got a job to do" and kicked into full gear and was trying to charge the whole boat through the ground system. That's the best I can figure out and that's why some of the folks, for a while, called me "Sparky". I've put lots of new wire in the tug since that day, and am happy to report all is again well and after 90 some days in the yard, Thistle Dew had a very smooth 7 hour run back to her home berth.
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