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.