Saturday, June 18, 2016

Regular System Checks

Unlike a house, often on a boat it isn't the best idea to wait for things to fail. When your home moves around a lot, it seems even more things can fail and fail more often.  As a result, I perform regular checks on all sorts of systems on the boat.

Since we are getting ready to go, I was performing some basic system checks related to moving the boat.  I turn on all the navigation related lights to make sure bulbs and circuits are behaving. Easier to change a lightbulb a couple days before we leave than that morning...particularly when it is only the fault of the bulb about 1/2 the time.  I check the standing and running rigging for any wear issues or other problems.

I check fluid levels, strainers, belts, and hoses, and other items on all the engines as well as give them a general look for anything that appears out of place (something that has gotten longer and longer as I run into issues en-route in our travels). I then start and run the engines a bit to confirm function. While tied to the dock, I test the transmissions to verify shifting and power and make sure there are no strange vibrations or noises. I engage the generator to verify it is also providing power (didn't think I would forget that motor, right).

One of our drive motors.

Those are only a few of the checks one does before heading out.  There are also a number of regular checks I do when just sitting at the dock.  Battery condition and charge, strainers and raw water output for air conditioners, inspection of bilges, and exercising through hulls are among those tasks.  I also try to run the engines and transmissions every 10 days or so even when we aren't going anywhere to splash oil around and hopefully knock off any growth that is trying to attach to the props.

Lots of checking and some fixing. One item I learned to check is what I understand to be the single largest cause of boat fires, the shore power cable.  And that is actually the subject of this post. After performing the pre-departure checks I did a few of the static checks.  I very regularly check the shore power cable and connector temperature by hand when we are running higher load items like air conditioners. I'm not sure exactly how often I check the connectors, but it is typically more than once a week.  If the connector feels warm at all, I will get the non-contact thermometer out for a better look.

In the past I've been able to write off most abnormal temperatures to heating from sitting in direct sunlight, but not this time.  With the air conditioners running regularly the last couple days I check the connectors at the power pedestal and the boat.  The boat-side connector felt warm enough to justify the the thermometer.  I get the thermometer out and sure enough, the connector was reading about 20 degrees higher than ambient at 115 Fahrenheit. The interesting part was that it seemed to be coming from a very specific point in the shore power cord connector.

Since I had the generator running at the time anyway, it was a simple task to switch the AC over to the generator and pull the power connector.  I checked the connector and didn't see any damage or obvious signs of overheating. But I figured it would not stay that way so we made plans to replace the chord. My guess as to the problem was that the connectors inside the boat-end of the connector (the female 30 amp twist lock plug) were getting weak or possibly bent and not making good contact. We monitored the plug and limited power consumption but the connector continued to be warm when we would run the air conditioner for any length of time.

Our long range solution is to replace the chord with a new Smartplug chord and boat connector.  I've looked at the research on the plugs and prefer the simple design with larger contact surfaces. Unfortunately these are not in stock anywhere nearby and we intend to leave soon.  So, as a temporary measure, we replaced the connector on the end of our current chord.  After replacing the connector, we again monitored temperatures and now the connector and boat side receptacle were remaining at ambient temperature. The old connector, when removed from the cord a day later was just starting to show signs of overheating at one of the connections...but it was still a far cry from the scary pictures I've seen in failures of these connectors. I'm very glad I monitor this regularly and caught this early.

Just a bit of discoloration at the socket end.
(Yellow casing removed from end of connector)

Being the curious sort, I decided to cut apart the connector I removed from the chord.  After all, it didn't seem like it was in bad shape at all and I had tried to take good care of the chord, using dielectric grease, always making sure power was off before disconnecting, always using the locking ring, and never forcing or over-twisting.  When I started cutting the yellow cover off of the connector, I found that the embedded screw terminal that clamps the wire to the plug's contact was charred and black. Further inspection revealed that the contact within the plug itself was in good condition and the failure point was indeed the screw clamp terminal. Why it failed I do not know.  Did water manage to make its way into the plug and start corrosion?  Did the wire not get clamped properly?  Was the fact that the wires in this Marinco cable don't appear to be tinned to help limit corrosion a contributing factor? We will probably never really know.

The failed screw clamp and charred wire inside the
molded boat-side connector.

All I can really say is that I'm very glad I checked that plug regularly and found this well before it became a bigger problem.  If you are plugged into shore power, please make inspection of these connections a regularly scheduled check.

A collection of failed twist-lock connectors from Compass Marine.
Read their article comparing these to the new Smartplug 

So what regular checks do you perform that may not be obvious but you feel are absolutely necessary?


  1. Good catch, checking the temperature of the connector sounds like a must do exercise.
    The fact that the Smartplug can be installed into the same cutout on the boat really makes it a must do replacement.
    I have been recently been more interested in power cords and connectors after a few projects here in Macau where several suppliers have supplied inferior quality power cords with equipment. The cords carry all the Euro and BS certification marks, but they are all counterfeit. Have been cutting open the cords and plugs to see how they are made, and the quality is so poor in some (can strip the insulation with fingers, conductor material is not copper, it just crumples in fingers) really dangerous to use.
    I would definitely go with something that has been produced in the USA where the quality is controlled.

    1. Just a simple touch with your hands sort of test on a very regular basis seems worthwhile. We walk by the connector just about every time we get on or off the boat, so it isn't really hard. And after all the pictures I've seen of full-blown meltdowns of those plugs, seemed prudent until replacement. Will write up more on the Smartplug after we get it installed, but for now the Compass Marine site has a great analysis of the connector differences. I only wish they still had the thermal breaker in the boat connector...was originally in the 30 amp, but they removed it for some reason. Still, I think it is a better option than the archaic twist-lock plugs.