Onboard lighting is a tricky thing when navigating at night. You need backlighting to see your instruments and electronics, and an overhead light to read a chart.
Yet once your eyes have acclimated to the dark, too much onboard light can destroy your night vision. Once this occurs, your eyes will need to readjust: Your pupils need to rewiden, and the rods, special cells that provide most of what we call “night vision,” must resensitize. This can take as long as 35 to 40 minutes.
With this in mind, most marine electronics allow you to adjust the brightness of the backlighting, and many units also have a “night mode” with a darker background to keep illumination levels to a minimum.
When it comes to instrument illumination, red is the best color since it doesn’t desensitize the rods. Most newer instruments are equipped with dimmers to adjust the intensity of backlighting and preserve night vision. If yours isn’t, a dimmer switch can be wired in for control. One of the latest is the DeckHand Dimmer from Blue Sea Systems ($99.98, bluesea.com). Most dimmers handle only one type of lighting, such as incandescent, halogen or LED. However, the DeckHand Dimmer can handle any or all of these lights at the same time.
Overhead and chart lights from companies such as Hella (hellamarine.com) are also available in red — including low-draw LED versions — should you need to read something at the helm.
When navigating at night, avoid turning on flashlights, spreaders or other bright lights that can destroy night vision. As on a romantic date, you want to keep the lighting dim.
Wherefore Art Thou?
Should your date paraphrase the classic Shakespearean question “Wherefore art thou, captain?” you should be able to point to your GPS/chart plotter and answer “right here.”
Thanks to detailed electronic cartography from C-Map (c-map.com), Navionics (navionics.com) and others, today’s chart plotters show a lot more than just your present position. Virtually any fixed object above water, such as buoys, jetties, exposed rocks and docks, show up on the plotter, just as it would on a paper chart, while at the same time showing the boat’s relative position to these objects. Chart plotters also indicate water depth, reefs and other submerged obstructions, so you can avoid running aground at night. A few chart plotters can also do some of the thinking
For example, with the Guardian alarm on C-Map-enabled plotters from Si-Tex (si-tex.com), Standard Horizon (standardhorizon.com) and earlier models from Furuno (furunousa.com), you can set a guard zone, much as you would with radar, that scans the chart area ahead and alerts you if your course is projected to put the boat upon shoals, rocks, sand spits or other threats.
“You set a minimum draft such as six feet and set a look-ahead distance such as a quarter-mile,” says C-Map’s Ken Cirillo. “Then the plotter looks at all possible obstructions, as well as shoals, in a searchlight pattern and alerts you to danger.”
Of course, a depth sounder is also important for confirming the water depth. Whether cruising at night or during the day, you should not rely solely on the electronic chart, particularly if the chart has not been updated recently. As to that, C-Map and Navionics both offer updating services, for a fee, and you can get updates from the U.S. Coast Guard’s Local Notices to Mariners at navcen.uscg.gov.