NMEA introduces new wiring standards
From Ocean Navigator #123 July/August 2002
Boats that were launched in the 1960s and 70s, for example, may have been equipped simply with a VHF radio, depthsounder and cabin lights when launched, but could have been retrofitted with various electronic gizmos over the years: satnav, loran, RDF, radar and, more recently, elaborate GPS and electronic chart systems and onboard computers. Even recent boats that may be equipped with numerous systems often suffer from a mixture of installation standards.
The NMEA has introduced new installation standards that aim to end the mismatched installation practices that vary across the country.
Lots has changed since NMEA started in the 1970s, said Larry Anderson, the NMEAs Standards Committee chairman. People can buy products from all levels of suppliers; that's one thing that's changed. And today, of course, systems are much more interrelated.
While most newly built vessels are installed to acceptable standards, according to the NMEA, older boats often receive systems from numerous, non-standard sources. Therefore, the new standards target so-called aftermarket installations. This is especially imperative now, according to the NMEA, with the advent of more integrated electronics systems like Furuno's NavNet and others. The standards apply to vessels between 25 and 125 feet. It is intended for installers, technicians, owners, surveyors and electricians, specifically for installation of CPU-based communications and navigation equipment, which have requirements for backup power sources. The standards are meant to complement the American Boat Yacht Council standards, particularly the section detailing DC systems.
"We do a lot of electronics installations here, and a lot of the gear we see malfunctioning is not because the gear is bad but because the installation is wrong." said Steve D'Antonio, boatyard manager at Zimmerman Marine in Cardinal, Va., and contributing editor to this magazine. Two of the most egregious examples are autopilots and single-sideband radios. The wire sizes are often too small for the required run. Then you get a voltage drop because of the length of the run. Same thing with single-sidebands. An SSB will pull 30 amps when transmitting. You don't want undersized wire. These new standards might make this sort of thing less common.
The NMEA is a trade association of manufacturers, distributors, dealers and sales representatives based in Severna Park, Md. For more information or to receive a copy of the standards, go to www.nmea.org or call 410-975-9425. The NMEA expects all licensed technicians to be fully aware of the new standards by January 2003. The NMEA's standards book costs $200 for non-members. The ABYC's guideline, which includes a section on electronics and information on boat construction and repair, is available for $150 at www.abycinc.org or by calling 410-956-1050.