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Chuck Husick: Techno-Talk, September 2004 from BoatUS Magazine -

Updated June 2009

Navigation Lights and Visibility

Boat owners spend a lot of time looking at boats, their own and everyone else's. We all enjoy the complimentary remarks of those who see our boats. However, the value of being seen is not limited to satisfying our vanity — there are times when someone else's ability to see our boat can be critical to our safety.

Boats, and even ships, can be difficult to see when visibility is reduced by mist, fog, rain or darkness. At such times your boat needs to be as visible as possible, radar reflector in place, navigation lights on and operating properly. No problem. Just flip the switch and your lights are on. Or are they? And if they are on, are they up to the task of making your boat properly visible?

Most recreational boat navigation takes place during daylight hours. Months may have elapsed since you last operated your navigation lights. The light from properly positioned navigation lights is largely invisible from the helm. Infrequently used electrical devices are particularly subject to corrosion in switches and lamp sockets. When did you last verify that all the lights were operating?

Your inspection may show that the sidelights (red port, green starboard), the white stern light and the white maneuvering light are all in order. However, even if the lights are working it may be worthwhile to clean the interior of the lens and spray the lamp socket with a bit of anti-corrosion spray. If your lights are old you might consider installing new fixtures guaranteed to meet the luminous range, color and horizontal sector specifications of Annex I of the Navigation Rules. The red and green sidelights must be visible from a distance of 1 mile if your boat is less than 12 meters in length, 2 miles for boats between 12 and 20 meters. Stern and masthead (maneuvering) lights must be visible from 2 miles.

The Coast Guard's publication Navigation Rules, International - Inland spells out the requirements for lights in Part C - Lights and Shapes, Rule 20 through Rule 30, Rule 38, Part E, Exemptions and Annex I and II. The essence of the rules for the use of lights is that they must be on when the vessel is navigating between sunset and sunrise and at any other time when visibility is restricted in any way. The space and the extent of the detail devoted to the light rules is a clear indication of the importance of having and properly using the lights on your boat. The Navigation Rules can be downloaded at:

Replacing old and possibly deficient navigation lights can improve both the safety and the appearance of your boat. Power and sailing vessels less than 20 meters in length may choose to install a single combination red/green sidelight at the bow. These lights use a special vertical filament incandescent lamp to deliver superior position reference information to oncoming vessels by virtually eliminating overlap between the red and green sectors. Sailors may elect to install a tri-color light at the masthead that can be used in place of deck-mounted lights when the boat is under sail alone. (Lighting the tri-color masthead light and the deck-mounted lights at the same time or when under power is not permitted.)

Navigation lights that use light emitting diodes in place of incandescent lamps are now available. The advantages of the LED lamps include very high visibility, even under difficult conditions, immunity to damage from shock or vibration and elimination of corrosion of lamp socket contacts since the long life of the LEDs (conservatively in excess of 20,000 hours and perhaps 50,000 to 100,000 hours) allows them to be hard-wired into the fixture. Sailors will particularly appreciate the power economy of LED navigation lights, 1/10th to 1/2 that of the incandescent lamps they replace. However, if you choose to install plug-in LED lamp units in place of the incandescent bulbs you may find that corrosion of the lamp socket is more troublesome than when the higher current incandescent lamps were in use. The lack of the very low cold resistance of the LED will prevent the formation of the minute arc that might have occurred with the incandescent lamp, cleaning the contacts and ensuring that the lamp will light. A visual check of all navigation lights is always advisable.

Before we close, permit me a pet gripe. While most boaters comply with the rule requiring display of an all-round white light on boats anchored in other than a designated anchorage, sailors often use a masthead light that can be 40 to 70 feet above the surface. Although the light meets the letter of the law it does a poor job of alerting the crew in a dinghy of the presence of the boat. We prefer the "old way," a light hung near the forestay not too far above the deck.

By Chuck Husick

Chuck Husick is a pilot, engineer, sailor and former president of Chris Craft Boats.

© Copyright BoatUS Magazine 2004

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