Unexpected Side Effects With New Stuff

By Tom Neale

Boating gear is improving. But you've got to watch out for some of those improvements. Occasionally they'll rise up out of the swamp and bite you.

Know your new equipment

Take common rail diesels, for example. Among the benefits are that they're supposed to be more efficient, and give us less pollution. And, when you look at the top of a common rail diesel, it even, according to your view point, may look simpler than all those pipes coming from a single injection pump, going to each injector, along with the return lines. And this isn't to criticize common rail diesels. But, there are a few things to know. One of these is that in that "common rail" is a huge amount of pressure. It's far more than the pressure in a diesel injector feed pipe between that old fashioned injector pump and the old fashioned injector. This means that if you breach that rail pipe while it's pressurized you can have a very dangerous situation, perhaps far more so than with the former individual pipes. It also means that you must be very careful dealing with the pipes, including "fixing" them. It's extremely difficult jury rig a fix for a regular diesel injector pipe (not a good idea) but you just don't want to mess with jury rigging any fix on the common rail.

Another difference is that this common rail is pressurized all the time the engine is running, while the old fashioned injector pipe is pressurized when the injector reaches its "turn" and pressurizes the pipe for the firing sequence. The firing sequence in a common rail system is a function of the injector, which is much more complex than the older ones. In essence, many common rail injectors are like very sophisticated solenoids. You can seldom solve an injector problem underway by blowing off the tip or soaking it.

Know the diesel you have and love and care for it. But don't assume it's like all the ones you used to have.

Another improvement, familiar to us all, has been the 4 stroke outboard. I used to resist them, but now I love them. But I need to remember some of the differences. It's not that they're just heavier. I love the fact that I don't have to mess with mixing that expensive oil in with my expensive gas. You put only gas in the tank and the 4 stroke gets its lubrication from the oil sump and pump, similar to what you have in your car. This is great, I've thought. But in the olden days we'd think nothing of spinning that engine without spark and/or compression (we shouldn't have but we did) letting the oil in the gas lube it in the upper end. This was done in many a repair or trouble shooting job. But you can't use the oil lube from the gas in a 4 stroke. It's not there. True, the engine will pick up some of the oil from the sump, but there isn't the same type of lubrication going on without that oil in the gas. I like the 4 stroke, but I honor the difference, both here and elsewhere.

There's another relatively recent piece of equipment that can cause problems for the unwary, not because of how we work on it but because of how we use it. Our state of the art inverters not only invert DC to AC on board, but are also often used as the primary battery charger. It's all very cool. When you're plugged in to the dock they juice up the batteries, set to the special requirements of the special batteries, not only as to type and size but also perhaps as to temperature. This is great. They do the same if you're running a generator. And you don't have to own a big yacht to enjoy these inverters. They can be relatively small and designed for use on much smaller boats. For example, some of our center consoles have a great cabin under the console where an inverter might be useful. But here's the catch.

Inverters, when we're not plugged in to AC current which is being used to charge the battery, typically automatically start inverting. That's great. But they do this by inverting the DC power from the battery. But they're doing more than not just making the battery DC into a corresponding AC. There's also the energy required for the process. The better inverters have a very low efficiency loss, others have more. This comes from what it takes to do the job. An example is when you find an inverter heating in the process. This is energy which can only come from the battery. Sometimes a fan will come on to dissipate the heat if it's doing a lot of inverting. This also requires energy which comes from the battery. Most of the time this is no big deal. We use the inverter to run a fan, to run a TV or microwave or whatever. Then we plug back in to the dock and it puts the juice back into the battery. But here comes the real catch.

If you have a storm while your boat is at the dock you're probably going to have water coming into the boat. Hopefully it's just a little and not a big deal, but sometimes a scupper can get plugged, waves can come over the stern or other things can happen that result in a lot of water. Sometimes it's just a very long storm with a lot of rain and a long time of dripping from that stuffing box you've been putting off fixing. Another thing that happens in storms is that often the power goes out. This is especially true in a severe storm and it's especially true in a tropical storm or hurricane. So there is no dock power. What does that inverter do? It automatically switches to the invert mode, consuming power from the batteries. You may not be running any AC user on the boat. Or you may be running something of low draw, such as the clock on the microwave. But that inverter is drawing power just in the process of inverting.

What else is drawing power? Your bilge pump when it turns on. Some of them draw power to "test the waters" even when they're not really running. The scenario is simple. With the inverter automatically switching to invert you're going to ultimately deplete your batteries if the dock AC power is off for long enough. This means that the bilge pump won't work. This means that the water coming in is staying in. And you know what that can mean.

All this can be simply handled. Just turn off the automatic function of the inverter when you leave the boat. You probably won't need it anyway. Most inverters have that switch and if yours doesn't then get another. Leave it on charge but switch to off its automatic invert function then the AC is gone. Problem solved.

Like many other boating improvements, you've got great equipment, it serves you well, but you just need to beware of how it works. 

Tom Neale is Technical Editor of BoatUS Magazine, with a lifetime of liveaboard and cruising experience. Read more of Tom Neale's articles here.

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— Published: April 2016

Tom's Tips About Knowing Your Equipment

  • It's really simple. Read the literature. Think through beyond the immediate functions. For example, if a fan is running, why and what is powering it? Or if something looks unfamiliar, find out about it.
  • Think through what the product is doing to see some possible consequences. For example, if you install a new more powerful alternator, you may need to also install a more robust V belt. The greater power may mean there's going to be more load on that belt.
  • Read it the manual the way through; don't just skim it.
  • If there's something you don't understand, call the manufacturer.
  • Also visit chat rooms if there may be an issue.
  • For some equipment you may want to learn from a mechanic or more experienced user.

See www.tomneale.com


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