Sailing to the British Virgin Islands in the Caribbean 1500

Navigation (continued)

Night Heron's helm, with the big (but dark) Furuno chartplotter. The Furuno system was turned off to conserve power. The wind instruments and bow thruster control are above the chartplotter; the autopilot handheld controller is to the right of the compass.   This is the nav station with the other Furuno chartplotter turned on. In front of the chartplotter you can see the small laptop computer running the MaxSea navigation software. Jeff has two laptops, the small one running XP and a bigger one running Vista, but compatibility problems currently prevent the Vista computer from communicating with Navnet (the Furuno ethernet network). You can see a handheld GPS to the right of the laptop computer. At left, mounted on the panel, are the radios (ICOM SSB and Furuno VHF). Below the nav station are the DC circuit-breaker panels and battery switches. Each panel has a vertical metal bar in front of each column of breakers, to keep you from accidentally bumping the breakers and flipping the switches. Click on the picture to see a bigger version; use your browser's "back" command to return here.

A Voyage In Three Sections

Our voyage consisted of three distinct sections, each with its own style of navigation:

  1. From Tidewater Marina out to the Atlantic Ocean - This portion of the trip required careful piloting, with the helmsman paying constant attention to the chart, buoys, other boats/ships, the depth sounder, etc. The main navigation goals were to stay out of the way of big ships, keep clear of the other sailboats in the fleet, avoid the restricted areas around government facilities, stay away from shoals, and in general follow the well-marked channel out to the ocean. Our navigation was mostly visual, by observing floating buoys.
  2. From near Cape Henry to near Anegada Island in the BVIs - This portion of the trip was an ocean voyage, with a different set of navigation requirements: adjust the autopilot to generally follow the chartplotter route, make course adjustments to accommodate changes in wind/weather/seas, keep watch to avoid ships, maintain a log of fixes, etc. Our navigation was almost entirely electronic, steering to arbitrary GPS waypoints that we had established. Although the helmsman still had to pay attention, this portion of the trip didn't require the same kind of constant attention and careful piloting as the first portion of the trip. We never had to worry about running aground—in fact just north of the BVIs, we sailed over one of the deepest parts of the ocean (the Puerto Rico Trench, with water depths greater than 25,000 feet!).
  3. From near Anegada Island to Village Cay Marina, Tortola - This part of the trip used electronic navigation plus visual navigation. Although there were buoys for visual navigation, they were infrequent and not totally reliable, so it was still important to follow an electronic route based on GPS waypoints. Water depths were critical, since any groundings might occur on rocks or hard coral rather than the soft mud of Chesapeake Bay. The final part of the trip in Road Harbour required the same kind of careful piloting as the first part of the trip.
Primary vs. Backup Navigation

While we were navigating the three sections of our voyage, we used two main types of navigation: primary and backup. For primary navigation, Jeff would create waypoints and plot a route using the MaxSea navigation software on the laptop computer, then upload the waypoint and route information to the Furuno chartplotter at the nav station. Once the information was uploaded it became accessible via Navnet, so the chartplotter at the helm could access the information and display the route. All the data transfers between devices took place over ethernet using a small router near the nav station. It was possible to create waypoints and routes directly on the Furuno chartplotters, but the MaxSea software was much more powerful and had a simpler user interface.

For backup navigation, we had three handheld battery-powered GPS units which were manually programmed with waypoint and route information derived from paper charts. We actually used our backup navigation for a good portion of the trip. After the genset failed, we had to reduce our electricity consumption since we were also trying to conserve fuel by not running the main engine. All the Furuno equipment together took about 10 amps of DC current, which over the course of a day amounted to 240 amp-hours of energy usage. Part of the reason for the big draw is that the same power supply also fed the radar and the weather fax. Also, frankly, the big Furuno chartplotters weren't really designed for power-miserly sailboats, and we had two of them. While using backup navigation, we would turn a GPS unit on to take a fix and to determine distance and bearing to the next waypoint. Since they were battery powered, we didn't leave the handheld GPS units on continuously (although we had plenty of spare batteries).

As part of our backup navigation, we had a set of paper charts for the entire voyage:

In case of emergency, we also had a list of "bailout" waypoints for major East Coast ports, although we didn't program them into any of the GPS units and we never had to use them. We also had a Reed's Almanac for the Caribbean, which had chartlets and approach information for all the Caribbean islands plus Bermuda. After our sails and genset were damaged, we did briefly consider heading to Morehead City in North Carolina, but an adverse weather forecast preempted that possibility.

For "local knowledge" in the Virgin Islands, we had a couple of cruising guides that had detailed information about anchorages and marinas. We also had on CD-ROM a copy of the American Practical Navigator and the International Navigation Rules.

There's more navigation information on the next page.

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