By: Nigel Calder
By: Chrystal Rozander
Issue #57 January/February 2026
In order to design, install, and operate a trouble-free boat electrical system, it is necessary to have a basic understanding of amps, volts, resistance, electrical power (watts), and electrical energy (watt-hours).
Electricity
Electricity is the movement of charged particles between two points. In our case, the particles are electrons.
Some materials, notably most metals, allow the easy movement of electrons. These are conductors. Other materials obstruct the flow of electrons. These are insulators. In electronics, we also have semiconductors.
In boat electrical systems, we use copper as the core conductor material, and various forms of plastic as insulation around the copper. The copper is often tin-plated to increase corrosion resistance. Occasionally, terminals are gold-plated for maximum corrosion resistance, especially in electronics circuits.
Metallic Conductors
Although this may not be technically correct, it is useful to think of the atoms in metallic conductors having ‘free’ electrons that are easy to displace. If one end of a conductor is confronted with additional electrons – for example, by applying a voltage – the electrons in the conductor move away because they have the same charge as the new ones and like charges repel one another. The new electrons push the existing electrons in front of themselves in the conductor to the next atom, displacing electrons on that atom, which in turn displaces electrons on the next atom, and so on.
In a direct current (DC) circuit, the flow of electrons is in one direction. A voltage is applied to one end of a conductor, introducing additional electrons, with the excess electrons driving the free electrons in the conductor ahead of them from one atom to the next until the same number of electrons emerge at the other end of the conductor – a current flows.
Think of a pipe filled with golf balls. Another ball is whacked in at one end, forcing a ball out at the far end. Each ball only moves a small distance, but in doing so, passes on the movement to the next ball. Even though the movement of the balls may be relatively slow, when a ball is driven in at one end of the pipe, the ball at the other end moves almost instantaneously…
