For centuries, navigators have been coping with two key variables that convey major consequence. The first is the quest for an accurate position fix, and the second is the hope that the chart theyre using is an accurate representation of their surroundings. Up until a couple of decades ago, cartographers were winning out and chart accuracy trumped sextant-derived fix accuracy. The tide has turned.
Heralding in a new era for electronic navigation, the U.S. Coast Guard recently published guidance that allows mariners to satisfy chart-carriage requirements using electronic charts and electronic publications instead of paper ones.
As we dug into the topic of electronic storage media-the memory cards we use for routine software updates on our marine electronics-we found that even the makers of our marine electronics were a little confused about which memory cards worked with their own systems. We soon realized that a data table indicating which cards worked with which electronics would be very handy. It was one of those easier-said-than-done enterprises that dragged on for weeks. Hopefully, our tables, compiled by PSs resident electronics expert, Bill Bishop, will be helpful as you dust off your chartplotter for the coming season.
Planned obsolescence is probably the most irksome way to keep manufacturing costs down and inspire us to buy stuff. Each time a new or updated line of multi-function devices appear, we ask ourselves if the new version represents real value, or are the engineers just adding another tower to their Lego castle, while the marketing folks ponder adding an umlaut or X to the product name.
For a more detailed look at the product, see our initial report in the July 2012 issue online. Heres a quick recap. The e7D is part of Raymarine eSeries HybridTouch line of multifunction displays (available in 7-, 9-, 12.1- or 15.4-inch display sizes) that combines touchscreen interface with a joystick-like unicontrol and features Bluetooth and WiFi connectivity. After our first report, Raymarine identified a touchscreen issue with some e7 and e7D plotters (see PS March 2014 online). A campaign to replace problematic devices with refurbished units is ongoing.
Before we plunge headfirst (again) into the world of multiplexers with this test report, heres a quick review of what exactly were talking about. If you have older instruments or a GPS networked to send information to other devices (a multi-function display, laptop, etc.), the information is likely in NMEA 0183 format and is sent in sentences in a set order. For example, the NMEA sentence $GPAAM,A,A,0.10,N,WPTNME*32 is an arrival alarm sentence sent by a GPS to various networked devices upon arrival at a waypoint.
NMEA 2000 (aka NMEA 2K or N2K) is the communication standard replacing NMEA 0183. It is a technical standard (IEC 61162-3) used for connecting marine sensors and display units within a boat. The major differences from NMEA 0183: NMEA 2K operates at 250 kilobits-per-second, about 100 times faster than the 4,800 baud of NMEA 0183.
A sailboat is no place for unnecessary complexity, which was the direction PS contributor Dan Corcoran was headed on his Beneteau 393, when it came to how data was passed between various marine electronics. The worst offender was a spaghetti network of point-to-point wiring that utilized the familiar National Marine Electronics Association (NMEA) 0183 standard. A few years ago, he embarked on a gradual replacement of NMEA 0183 wiring and components with the new standard, NMEA 2000. Here he offers his account of the upgrade and answers the oft-asked refit question: Was it worth it?
Being natural-born skeptics, Practical Sailor testers are always pleasantly surprised when we test gear that meets-or almost meets-the hype from its makers and marketers. And that was just the case with Navicos GoFree WiFi wireless networking device for Simrad products. We recently field tested it, and found that aside from a few niggles, the GoFree lives up to makers claims, is easy to install, and works well-straight out of the box!
As ventilation experts explore ways to make indoor spaces safer during the COVID-19 pandemic, we became curious about ventilation in our boats. As it turns out, where we install our exhaust or intake vents (portlight, hatch, or cowl) is just as important as what type of vent we use. Just as we can use the suction on the leeward side of a sail to pull the boat forward, we can use pressure differentials in the air surrounding the cabin to maximize the ventilation. Understanding the pressure differentials created by the flow of air over our boat’s deck is vital to the success of any passive ventilation scheme.