Members' Online Book: Battery Installation & Maintenance, Chapter 3 of 23

One Simple Law That Makes Electrical Systems Easy to Understand

Main 12 volt bus wiring on "Morgan's Cloud".

12 volt main bus wiring on “Morgan’s Cloud”.

It never ceases to amaze me how ignorant many, perhaps most, technicians around boatyards are about how electricity works. Yes, even those who have worked on boat electrical systems for years.

But the ignorance of said technicians pales into insignificance when compared to the pure unadulterated rubbish spouted by many people who sell marine electrical equipment.

And that brings up a further problem: some people who can’t even calculate watts when given volts and amps, are still willing to advise the unwary about electricity.

And don’t even get me started on the level of BS that flies on the forums when things like batteries and charging are discussed—you could drown in the stuff.

So what’s the point of my ranting, other than I now feel better having let off steam? Well, we boat owners can waste a boatload of money and still end up with an inefficient, unreliable electrical system if we don’t have the basic knowledge to determine whether or not the person who is working on our boat or advising us knows what they are talking about.

Sometimes they do and all is good but, distressingly often, so-called “professionals” are just spouting one of the many myths that have grown up around marine electrical systems or, worse still, bending the facts to sell a product or excuse one that doesn’t work.

The good news is that if we understand just a little bit of electrical theory we will immediately be able to detect the rich aroma of marine electrical BS before any harm is done. And the even better news is that this stuff is not that hard to grasp.

In the next couple of chapters, I’m going to make this easy and give you real examples of how to apply this to your boat’s electrical system. Practical knowledge you will use every day.

Let’s do it.

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Meet the Author


John was born and brought up in Bermuda and started sailing as a child, racing locally and offshore before turning to cruising. He has sailed over 100,000 miles, most of it on his McCurdy & Rhodes 56, Morgan's Cloud, including eight ocean races to Bermuda, culminating in winning his class twice in the Newport Bermuda Race. He has skippered a series of voyages in the North Atlantic, the majority of which have been to the high latitudes. John has been helping others go voyaging by sharing his experience for twenty years, first in yachting magazines and, for the last 12 years, as co-editor/publisher of AAC.

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