By Tom Neale, 6/12/2008
Diggin Into Bag of Tools and Tricks
Impending doom isn’t a feeling you should have when you get underway. And it isn’t a feeling we have. We usually have feelings of joy and excitement. But always gnawing in my craw is the recollection that “stuff” happens on a boat. Probably the worst “stuff” that’s been dumped on me has been in the dead of night or during storms. But “stuff” can happen anytime, and it often seems that it mostly happens when you’re getting underway, or shortly thereafter.
So every time we get underway I prowl around the boat checking for things. When we’re motoring I always head for the engine room first. I squat down and look, listen and smell. I check around for the millions of little things that could have gone awry since we were last on the move, but that I may not have noticed until I fired her off again.
A few days ago, as we steamed out of harbor, I routinely opened the engine room door, wondering if I’d ever get over my paranoia so that I could just take off without the sacred rite of checking things out. Immediately I smelled something hot, like something burning, but I didn’t recognize the smell. Many things can burn on a boat, ranging from the meat for the evening meal to the boat itself. There are lots of things in between, and none of them are good.
As if that wasn’t alarming enough, I also noticed what seemed to be a very slight amount of smoke in the air. Not good. Incredibly not good. When something’s not right, the first job is usually to diagnose the problem. If you’re “lucky” (like when you’ve just hit a container and you’re going down fast) you may already know what the problem is. But so often we, at first, only notice the symptoms—not the cause.
I immediately yelled out, asking Mel to bring the throttle all the way back and stand by. I considered an immediate shut down, but wanted a second or two to eliminate some possibilities. I quickly looked at critical areas of the engine and very carefully felt things. The alternator seemed too hot. All else seemed OK and I noticed that the smell was changing. Not getting stronger, but changing. Strangely, the engine room smoke and fume alarm hadn’t sounded, so I figured things weren’t too bad yet, but anytime you smell and feel heat and anything remotely like smoke you know that things can go downhill very quickly. Fiberglass boats, once they start burning, can burn extremely rapidly, emitting overpowering and deadly fumes.
It had been a minute or less since I first noticed a problem and I still hadn’t a clue as to the cause so I yelled to Mel to “shut ‘er down.” The silence would make it much better for me to listen, although the problem was apparently at least partly associated with the engine running. But in the back ground of my mind was the disturbing recollection that I’d worked on some wiring in the engine room last week. It was just some simple improvements, and I’m fanatically careful about things like that. But. But. How could it be? But…
I raced around the boat, checking everything I could think of that could be even remotely likely to cause the symptoms. I quickly noticed that my “house” battery bank (two Rolls Modular 8Ds) was being drained at the rate of 52 amps. This isn’t necessarily bad on my 53-foot boat with its many systems. But I could think of nothing that would be consuming that much at the moment. The only normal source would be through the main inverter but nothing that would normally cause that draw, such as the microwave, was on. Then I saw the amp draw drop. Something was changing. And I heard a different sound. The ice maker had changed its tune. Viola! When the compressor on an ice maker starts running, there’s a surge draw. And it usually does this right after the ice dumps. Right before the ice dumps, many ice makers, for a brief period of time, use a small heating element to melt the ice enough so that it’ll dump. Either of these would cause temporary higher amperage consumption—but not that much. Then I remembered something else.
When we’d left the dock the wind had been blowing hard from a bad direction so I’d used my bow thruster. I noticed that it seemed weaker than usual. Hmm, probably from weak batteries, I thought. I have a bank of two Group 30s in the bow dedicated to the bow thruster and windlass. I raced forward. No bad smells, nothing hot, but the battery charger for those batteries was putting out its top level. The batteries had been topped off before we left. Now they were very low from just a little bit of use. I turned off the charger and the ice maker and the amp draw from my main house bank dropped to very low. But, as I said, even a 52 amp draw is neither unusual or a problem for our system. That draw shouldn’t have caused the smell or possible smoke.
I ran to the engine room again. The smell was gone. The alternator temperature was normal. I looked at it closely. I saw a tiny shaving of insulation, apparently dropped while stripping wire for the installation of new terminals, laying on a hot part of the alternator. It had partly melted and crisped. But I know the smell of burning or overheating insulation. It’s as plain to me as the light of day. And that wasn’t what I’d smelled. Or was it?
As I was pondering this I instinctively depressed the alternator belt with my thumb. I do this all the time (when the engine’s off) because it’s important to keep belts correctly tensioned. I’d been checking this even more lately, because it was a new belt and they stretch at first. It was just ever so slightly loose.
The end of the day was worth the trouble
When the alternator suddenly experiences a high demand and starts putting out amps at its high end, it has to “work” harder and the belt has a much greater resistance to overcome and there might well be slippage resulting in, among other things, the smell of an overheating and slipping belt. That was another smell that I was very familiar with. I was also familiar with the smell of an alternator running at high output. I just wasn’t familiar with all of these smells, including the melting shave of insulation, mixed in together.
When a problem rears its ugly head on a boat, it’s often caused by multiple things happening and interacting at the same time. Weird coincidences that don’t make sense at first blush aren’t unusual. True, I’m sitting on a fairly complex boat as I write this, but I’ve found the same to hold true, many times, on my 20 foot center console and my 12 foot dinghy.
This fact of life can cause some supreme frights, but it sure makes you feel good when you figure it out and all is well again. But I know I’ll never stop checking—even if I do turn up some false alarms now and then.
Copyright 2004-2008 Tom Neale