Marine Electronics

Over the years Practical Sailor has done many articles analyzing VHF radios, chart plotters, etc. This article will discuss how to get various brands of electronics that use different communication protocols to work together seamlessly. It is proven to work on my 39-year-old personal boat and parts of this process has been used on boats I have delivered for my customers.

The NMEA 0183 has two different communication (baud) rates for-4800 baud and the faster 38400 baud (also known as NMEA 0183-HS). You have to match the baud rate of both devices for communication to occur. AIS will always use the faster rate. Once the speeds correlated on our test boat, the radio presented targets on its one-inch display. Sitting at the dock it was apparent that info below decks was useless.

Although wireless systems have gradually made their way aboard modern cruising boats, hard-wiring remains an essential part of most systems, especially when you are matching old and new gear, or using converters. One of the biggest challenge for those of us with terrible fine motor skills is dealing with the tiny wires. Stripping, splicing and connecting these wires isn't neurosurgery, but definitely not the sort of thing you want to deal with on a rocking boat. But like any installation, it is a job you want to get done the first time-especially when you consider the challenges of troubleshooting electronics faults.

The human body runs on electricity and if you overload the nervous system with an external field, everything goes haywire. Every year several people die because they go swimming near a dock, a wiring fault creates an electric field in the water, and their muscles freeze. It is called Electric Shock Drowning (ESD).

Most of us spend a great deal of time away from our boat. Whether shes on the hard, moored in our home harbor or anchored in a foreign port, we want to know whats going on with critical systems. Is my vessel where it should be? Has someone disconnected a power source or tried to gain access? Is the bilge pump cycling more frequently? Is the house bank okay? Is the freezer holding its set-point? If your boat was struck by another vessel, wouldnt it be helpful to have photos?

There are two primary wind indicators on a sailboat. First, we watch the sails. Sailing to windward we watch the jib for luffing and for flow on telltales.

Mast antennas, like all electrical components, are particularly vulnerable to water intrusion at connectors. In the extreme, corrosion at unions or terminals can damage a transmitter.

The U.S. Coast Guard continues be concerned about the misuse (or lack of use) of VHF radios for distress calling. Many boaters, it seems, don't understand the importance of registering their radio equipment, and how to properly use Digital Selective Calling (DSC) feature. Here we offer a brief overview of the most frequently asked questions regarding DSC. More information can be found at the Coast Guards Navigation Center website, www.navcen.uscg.gov.

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.