Again!?

There I was sitting up in the flybridge enjoying the view and a morning cup of coffee while reading about some of the new things discovered by the JWST (James Web Space Telescope). Cool stuff that, enough to keep one's attention. So the first whiff of something getting way too hot didn't really register. The second snootful however, clearly hot rubber smoke mixed with electrical fire stink, set off every emergency warning bell in my brain. Within seconds I was down the ladder and in the salon, startling Deb with the worst words one can hear on a boat, “What's on fire?” But my brain, informing my feet without bothering to inform my head, already knew what was wrong and had them (my feet that is) heading out the side door and onto the dock. Sure enough our brand new shore power cord was smoking, turning black and, even as I moved to throw the dock-side breaker, bursting into flames. It wasn't a big fire. Grandson Eldest, having been rousted out of his berth when the AC went down, was right behind me, fire extinguisher in hand. A quick squirt was all it took to go from “EMERGENCY” mode to “What the hell was that all about?” curiosity. 

Two fires in less than a month? Something is clearly amiss. The first thought was that the “Y” splitter, 50A > dual 30s, was the culprit. That side of the connector to the 50 foot shore power chord was clearly the most heavily damaged and the original source of the way-too-hot. But that particular connector was brand new, one I had replaced after the first fire. I'm not perfect and may not be any good at a lot of things. But I am pretty good around electrical work and putting a connector on the end of a wire is not exactly brain surgery. But discretion is better than arrogance. Something was seriously wonky and I didn't know what is was. But, whatever it was, I was at least in some way clearly responsible for it.

We went out and bought a fancy new Marinco “Y” adapter complete with EEL connectors. No more splicing a new connecter onto an old chord. And though the damage was limited to the last six inches of the brand new (Marinco again) 50' 30 amp shore power cord, it also went in the trash and was replaced with new. (Yep, Marinco.) But I went poking around some more because something in the back of my my mind was telling my brain that I was being stupid and missing something obvious. Prodded by that feeling, we powered up the Air Con side of the AC power panel and brought the units on line one at a time. With just the forward unit running the amp gauge showed 12 amps. With both units on line I was looking at 28 amps, maybe a touch higher. More musing and I felt like was was looking right at the problem and not seeing it. Then...

The something floating around was a vague memory that the amp rating is for intermittent loads, not continuous loads. Thirty amps intermittent would be roughly 20% lower; 24 amps in this case for a continuous load. Both times we have smoked a shore power cable was with the Air Con running full blast for days on end. But it was (is) only a vague memory at best. So I went looking, starting the search by pulling up the Marinco Operations manual for the ELL shore power cords: ZX449 MAR_TL_032_0112. I read through it several times and didn't see a word about the 30 amp rating being for intermittent loads only. Not even under the “overheating” troubleshooting guide does it suggest that the cord is not rated for 30 amps continuously. Other Marinco literature also suggests that overheating is almost always a corrosion problem, not a word about amp draw over a long period of time. In addition a West Marine DYI shore power post also suggests that almost all cord failures are due to corrosion, not pulling too many amps. So running a 30 amp system at or near 30 amps continuously, at least for all of the official documentation that we could find, should not pose a problem.

And yet, now that I am deep in the rabbit hole of this whole ordeal, I am sure I remember picking up somewhere along the years that the amp carry ratings are always intermittent. After several hours of both Deb and I swimming through the murky waters of the internet we did find a post on the Sailboat Owners dot com forum that talks about the difference between continuous and intermittent.  (We also found and interesting read with USCG Safety Circular 81. It says nothing about continuous vs intermittent ratings, but it is still a good read.)

So, I'm going with I was stupid (or uninformed, or forgetful, depending on who is reading this). I smoked two cables and nearly burned the marina down by running the shore power at its max intermittent rating rather than at max continuous for long periods of time. For now we will run the salon (aft) AC in the day and the berth (forward) AC at night. The inside of the boat is about 15 degrees warmer both night and day, but I've had enough fires for one summer.

My bad. But being stupid (or uninformed, or forgetful, depending on who is reading this) is not the same as staying stupid (or uninformed, or forgetful, depending on who is reading this). And now you know what (I think) I know.  

Ps: I'm still going to ask if the Marina owner will check the output voltage at the dock. We are at the end of that circuit. Though this is a bit of a reach, low input voltage could cause or exacerbate an overheating problem caused by amp draw. I'm feeling pretty confident that running just one AC at a time will keep us out of trouble. But I would really like to know that I have scraped every side of this rabbit hole, and actually grasp how it is I nearly burned down the marina...twice.

 

Gremlin hunting

Getting the Dink lift system squared away slowed the project work on First Light to a crawl. Most of our days are filled with taking long walks in a beautiful space and practicing music on a variety of instruments. Which, one has to admit, is a quality of life most of the people sharing this little planet with me can't even imagine, let alone enjoy. Having access to life-saving technology expertly applied is another gift I'm not sure I deserved, but I am deeply grateful and clearly on the mend. We are not on our way North yet, but that is okay. Life unfolds as it will.  

During our walks we touched bases with new friends who were also trying to get underway. Their delays have all been mechanical rather than medical. With no projects underway on First Light and no longer being completely inoperative myself, pitching in on their projects offered a chance to be a little useful. One project was helping finish up a wiring project to improve their Dink lift system. Theirs is one of those boats where the Dink rests in a cradle up on the Fly Bridge deck. It is a big lift and having electrical winches providing the grunt was nigh onto necessary. If there is a better way to spend a nice day in a pretty place than helping out a friend with a fun project, I don't know what it might be.

The project went so well that the next afternoon they left the dock to anchor out, intending to head north early the next morning. The next morning, we watched from shore as the Dink lift system was put to its intended use. (They had towed the Dink out to anchor.) Then we helped out as they motored back to the marina and settled into a slip to address generator, charging, and bow thruster problems. It turns out a “dry run” out to anchor is not so much a misnomer as it is a good idea. I was already standing there so I offered a hand and a half of support. Once upon a time I was a reasonably good troubleshooter. They had a few problems that definitely needed shot. A few hours later and a fuel leak in the generator had been reduced to minor weeping. Still not fixed, but good enough to get the genset up and running so we could hunt down the surging problem and then the charging glitch. Those took just a little longer to corner than had the fuel leak, but soon enough both of those gremlins had been dispatched to gremlin heaven. And so we started hunting for the bow thruster gremlin.

It appeared all the wiring was okay, connections tight and correct. Given the fact that it had seemed to work the evening before, some thought was given to the gremlin having shoved something into the impeller. There was also some reasons to suspect the motor as the culprit, so it was pulled to be taken to the shop the next morning for a bench test. Come morning it passed with flying colors. No gremlin hiding there. Once reinstalled, additional searching commenced with a diver added to the hunting party. The impeller was unimpaired and the gear box spun freely. The controlling relays were checked and rechecked. Wiring was wrung with ohm and volt meters. But the Thruster Gremlin remained unscathed. Every part of the system had been throughly inspected, motor, rotor, wiring, connections, battery charge, control circuits and relays, all were checked and rechecked with nothing being found that was amiss. Yet the motor would barely come up with enough speed to push the bow. As the search went on a tickle, somewhere in the back of my rusty mechanic's mind, demanded attention. I knew I was missing something obvious but could not, for the life of me, come up with what it was. Any mechanic who has ever been armpits deep in a problem they couldn't explain will know exactly how I was feeling.

Thoroughly puzzled, and (perhaps) a bit frustrated, I pulled the covers off of the battery boxes and, as expected since they had been checked at least twice already, found nothing wrong with any of the connections. Voltage across the two batteries wired in series showed the expected full charge of 27+ volts. A reading verified by the app on the DC to DC charger tasked with keeping those batteries topped off. But something was wrong. The tickle turned into a mental head smack. I was looking right at the gremlin and still could not pick him out. (Those of you who figured out the problem a few sentences ago can now take a bow.) Not knowing exactly why, I brought the volt meter into play right at the power connection into the control box and had the system activated. The 27 volts immediately dropped to 5. The bell finally went off in my brain. Of course! What had been bothering me all along was simply the sound of the thruster made when the system was engaged. It was that of a DC motor struggling with too little juice to get the job done. How many hundreds of times have I heard that sound over the years? And how, pray tell, had I not recognized it during a full day of troubleshooting? 

I looked the batteries over again, this time with a jaundiced eye. The top of one appeared to be slightly distorted and freckled with fluid. A sticker on both batteries said "J6". A quick search by my parts guru suggested those were date stickers; Oct, 2016. Seven year old AGMs in a bow thruster install, and a motor trying to push the bow around with only 5 volts of shove available? The gremlin was now squarely in our sights. Purchasing and installing new batteries pulled the trigger and said gremlin was no more. The next morning we gathered at the slip for final goodbyes and to toss lines. The bow thruster growled with purpose and my friends were on their way North. I am as pleased with their successful departure as I will be when we eventually follow.

That is still a month or more away. Maybe, in the next couple of weeks, we will do a short “dry run” ourselves. Just motor a couple of hundred yards toward the bridge, drop the hook, spend a day or two, and see what mechanical critters come creeping out to play. Then head back to the dock to hunt them down and chase them off. 

Voodoo Princess

Learning the ins and outs of a 30 year old boat maintained by a string of clueless monkeys takes a long time; longer than the two plus years Kintala and I have been beating on each other. We are currently tied to an underpowered dock, living on the hook if you will, without the hook. Every day ye 'ol Honda comes on line to fill the boat with electric juice which, on any other boat, would be a no-brainer kind of thing. A few days ago a bunch of electrons tripped over each other when we tried to run the vacuum cleaner while "on the gen". Nothing was obviously wrong so, after puzzling over it for a few, I reset all the breakers and CFGIs and tried again. Success.

This afternoon the electrons stumbled again. Resetting brought things on line just as before, but 'fridge and water heater were left off just to try and understand what was what. There was good AC power on the interior outlets but no charging voltage was going to the ship's batteries. Say what? There is no "BAT CHARGE" switch anywhere, so the working assumption these past two years has been that the battery charger was hard wired to the AC, flowing electrical juice into the batteries whenever the AC and DC were both on. This was not happening, and since battery charging is the life's blood of a boat living off the grid, serious poking and prodding ensued.

Checking the battery charger showed it dead as a door nail; could we have roached the charger somehow? But wait, why is the battery charger plugged into a standard house outlet mounted in the equipment hole? There is no switch marked "Equipment hole outlet" on the AC power panel. And what is this other thing plugged into the same outlet, the 'fridge? But there is a switch marked "REFRIG SHORE POWER", something that is clearly not factory.

Ah Kintala, you sneaky little voodoo princess you. It turns out the battery charger and refrigeration units are both plugged into that standard house outlet mounted back in the equipment hole. I've noticed it in passing but it was just more weird wiring in a boat full of such. This, it turned out, was the focus of the current electrical poltergeist, the battery charger is only powered up when the 'fridge switch is closed. Slapping REFRIG, OUTLET, and WATER HEATER switches all at the same time leads to weirdness in the Honda. Something we never noticed on shore power where one just turned everything on as a matter of course.

One can, of course, power up just the battery charger by going into the equipment hole and physically unplugging the 'fridge before closing the FRIDGE SHORE POWER switch. It would be better, much better, to rewire the boat and eliminate such weirdness altogether. But time and funds and a shrinking weather window make a total rewire something that must be put off until later.

This is a bit disconcerting since I have no real information on how much of a load this spooky wiring can take. All I can go with is that is has worked this way just fine for several years at least; and maybe a couple of decades. Who knows since monkeys never take credit for their work or leave any incriminating paperwork lying around. So for now understanding the voodoo will just have to do.