The Practical Mariner's Book of Knowledge by John Vigor

Author:John Vigor
Language: eng
Format: epub
Publisher: McGraw-Hill Education
Published: 2013-08-14T16:00:00+00:00

Navigation Lights, Specifications for Fit the brightest lights for which you have power or battery capacity. Colored glass absorbs 85 to 90 percent of the light from the bulb.

With a 12-volt system and lights showing through clear glass or plastic in the most favorable weather conditions:

• A 24-watt bulb is visible at about three miles.

• A 12-watt bulb is visible at about two miles.

Showing through red or green glass or plastic in the most favorable weather conditions:

• A 24-watt bulb is visible at a little over 1 mile.

It is interesting to note that to increase visibility from 3 to 4 miles, the brightness of a lamp must be doubled.

Most lightbulbs on private sailboats are incandescent, despite the fact that several manufacturers have developed light-emitting diodes (LEDs) that meet Coast Guard requirements. These LEDs require much less power than incandescent bulbs, an important consideration for yachts with limited battery capacity, but are much more expensive than incandescents. For example, a typical incandescent masthead anchor-light fixture retailing for about $70 costs about $215 in an LED version. On the other hand, compared with a typical anchor-light incandescent bulb drawing 0.42 amps, an LED array draws only 0.2 amps for an equal light output. The use of LEDs both for navigation and interior lights will undoubtedly increase as increased sales volume and competition bring down manufacturing prices.

See also: ANCHOR LIGHT, REQUIRED SIZE

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