Electrical

As a subscriber, you have free access to our back-issue archive-more than 2,000 articles. Here are a few topics you might find relevant this season.

The loss in RF coaxial cable increases substantially and quickly, when there is water intrusion. Coax that uses foam dielectric, like RG8X and LMR type coax, is particularly prone to this problem because the water can quickly propagate along the foam dielectric used in these type coaxes.

Recreational marine VHF antennas are usually broken down into three categories: 3- and 4-foot sailboat antennas (3dB gain), 8-foot powerboat antennas (6 dB gain) and 16-plus-foot, long-stick antennas (9+ dB gain) that are popular on larger, long-range craft. Antenna gain is a ratio related to an antennas effective radiated power (ERP) instead of a fixed quantitative value.

No one really wants just practical gifts, so weve tried to locate a few items that go beyond pure utility for this holiday season.

One of the often overlooked maintenance items in the pre-season rush to the water is the AC shorepower system. Over the years of surveying, Ive amassed a small collection of scary photos from past surveys showing the common examples of neglect to this critical system.

Movies can be corny, but Jack Sparrow nicely summarized the romance of sailing: Thats what a ship is, you know. Its not just a keel and a hull and a deck and sails, thats what a ship needs but what a ship is ... what the Black Pearl really is... is freedom.

Keeping batteries fully charged is a science that cruisers have to master sooner or later. If todays high-capacity AGM batteries arent managed properly, valuable amp hours in can permanently trickle away through sulfation, as we saw in our test of AGM batteries (See Fighting Sulfation in AGMs, PS May 2015). Good battery management means complete re-charging that matches the charging profile of your battery, and this means an accurate sensing of battery voltage. As we saw in our recent report on battery monitors (see Best Battery Monitor Test Update, PS October 2017) a good monitor will also keep track of temperature, as this can be a limiting factor in charge acceptance rate.

Our test focused primarily on the small-wire connections tensile strength, with and without solder, but we also looked at their durability under tough environmental conditions. We tested the pull-out strength without solder and the pull-out strength of soldered connections at 400 degrees by heating the connections in an oven to simulate overheating conditions. We tested fatigue by spinning a 6-inch length of splice wire at 650 RPM in a simple device that we called the wire-fatigue whirligig. Finally, testers soaked all samples for four months in salt water to accelerate corrosion, and then, we repeated the fatigue test.

Connecting two standard-size wires is pretty straightforward: Grab a ratchet crimper, adjust it to fit the crimp connector, strip the two wires to fit into the butt connector, slide the wires into the connector, and squeeze the crimper. The required materials are readily available: butt connectors for inline splices, ring connectors for terminal blocks, and a dab of anti-corrosive grease for the bolts and rings. Done right, these connections can survive some extremely tough conditions. In a recent test of anti-corrosion greases and connections, we demonstrated how these connections can last up to five years in the worst bilge conditions.

Two recent tests graphically demonstrated the importance of monitoring state of charge in a boats batteries. hese tests demonstrated that a sealed batterys capacity will be reduced over time, if its never brought back up to a full state of charge. But just how accurate are the monitors we use to gauge our batteries states of charge?