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Marine Electronics

Preventing Electric Shock at the Dock

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).

Deck-level Wind Vanes

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.

Crimping and Sealing for a Life Offshore

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.

Special Report: How to Prevent AIS and VHF Antenna Malfunction

Safety of Life at Sea (SOLAS) ships-including tankers, passenger vessels and cargo ships over 300 gross tonnage-must be equipped with Automatic Identification Systems (AIS). In the U.S., carriage requirements also includes vessels over 65-feet. AIS can allow you to see a distant ship, but is not a substitute for radar.

Register Your VHF Radio

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.

Testing VHF Coaxial

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.

Antenna Gain and VHF Transmission Range

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.

Heat-Seal Connectors

A typical cruising boat has thousands of electrical connections. The consequence of failure range from a light that doesnt work to a fire that can cost lives.

Mailport: Low Budget Navigation

Regarding the article on recycling gear for cruising in the September 2018 issue, I found that an old Windows laptop, with an external GPS puck and running OziExplorer, makes a fabulous chartplotter. The software is just a hair over $100 and is capable of using NOAA charts, USGS topo maps, aerial photographs, and any other map that can be put in registration, using only latitude and longitude of a couple of points on the map.

Know Your Life Raft Inspection Requirements

The experience of the owners of the 14-year-old, six-man, valise-stored Avon liferaft pictured here reminds us of the importance of following the manufacturers inspection schedule. With air leaking from the seams and through the fabric itself, the raft is a graphic example of how even a professionally serviced liferaft that remains dry in its hard canister can deteriorate to the point of becoming worthless.