[C320-list] muffler and electrical excitment

[pat reynolds]

As a religious follower of the wisdom imparted on this site since its' inception, I have been fortunate to have avoided many of the problems cited, ie; head odors (freshwater boat), charger problems, corrosion etc.  In the 15 years we have owned the boat I have only had the muffler and the electrical fuel pump replaced. ( I know, I just opened pandora's box).  I do have a water under the liner problem which I have been meaning to address for several of those 15 years (again freshwater only).  I think fortunately however that that problem may have saved the boat.

On a recent single handed return from a long distance race on Lake Michigan (blessed freshwater) I was awaken at anchor at  3 am by the bilge pump cycling.  It seems that the year old replacement muffler I had gotten from Catalina had developed two leaks in the bottom (worse than the 14 year old one I replaced) and motoring that day had filled the bilges and assorted pockets.  Tired and grumbling since I was still 100 miles from home, I removed the floor boards and hand pumped for a couple of hours.  Some of the water remained, as always, under the liner.  

I had the muffler reglassed at the next port and continued on.  Two nights later while in a slip, again at 4 am during a bad electrical storm, I smelled something burning.  I had a fan running off the shore power and thought it had overheated but it was cool.  I turned on the cabin lights which run off the batteries and noticed a faint wisp of smoke coming from behind the electrical panel.  It was heavier when I opened the panel.  Opening the battery compartment I could see that the charger wire insulation had burned completely off and these wires had fused onto and burned the battery cables.  These wires run under the liner through conduit from the starboard to the port side.  Apparently a power surge at the marina had come in thru the shore power cord, burned out the charger and started the electrical fire.  When they pulled the wiring and conduit out I could see that the conduit (pvc pipe) was burned completely thru under the liner.  I am thinking
 that maybe the water underneath had helped keep the fire from spreading.  Except for all of the wiring, charger and battery switch all else was ok.

The electrician did not reconnect the charger wires directly to the battery, but to the battery switch with fuses.  He said that would alleviate some of the wiring running underneath the liner.  He also said that the reason that the charger breaker did not pop was because the charge went thru the negative side seeking ground.

This was just a long way of saying that we should be aware of the wiring which is run thru and under the liner from the engine, charger, panel etc.  In additon to being inaccessible it may also be subject to chafe and fraying.   If I am ever on the boat again during an electrical storm I will immediately remove the shore power cord.