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Author Topic:   Navigation Light Nomenclature
jimh posted 06-29-2012 08:53 PM ET (US)   Profile for jimh   Send Email to jimh  
When boats operate at night or in periods of reduced visibility, the rules of the United States Coast Guard, in accordance with the International Rules, require that certain lights be shown from the boat. These lights are called the Navigation Lights. Let us have a few words about Navigation Light nomenclature.

The rules requires that a vessel show certain lights. The word lights refers to that which will be seen by another boat, that is, the light itself. We use light to mean the actual light that is emitted from the boat. Light is the visual stimulus seen by a person from another vessel when he looks at the vessel that is showing the light. It is this light that is subject to the regulations.

The light or lights from a boat or vessel that is to be in compliance with the navigation rules comes from lamps. Although in colloquial or ordinary speech the words light and lamp are often both used to mean the physical device that produces the light, when discussing navigation lighting, we use light to mean the actual visible stimulus and lamp to mean the device that produces it.

If we examine closely the components of a lamp, we find that there is a source of light inside the lamp. Typically these days the source of light is electrical in nature. It is very common that a miniature incandescent lightbulb provides the source of light in a lamp. It is also common now that a light-emitting diode, universally abbreviated with the acronym LED, is used as source of light in a lamp.

For some common types and sizes of miniature electric lightbulbs there are now replacements made from light-emitting diodes that can be used as plug-in substitutes. These devices are usually small assemblies of surface mount device light-emitting diodes, or SMD LED's for short. The term surface mount device refers to the manner of packaging the electrical LED device. A surface mount device typically has no leads attached. It is intended to be placed on a circuit board and soldered directly to the board with its solder pads. The packaging is designed to tolerate the heat that will be used in soldering. It is now very common to find a wide variety of SMD LED assemblies built to be used a substitutes for miniature incandescent lightbulbs in existing lamps. Such assemblies are called substitute (or replacement) SMD LED lightbulbs.

With regard to navigation lights, the rules carefully define the lights and give specific names to them. For a power-driven vessel there are only a few lights that need to be shown, and they are called:

--sidelights
--masthead light
--sternlight
--white all-round light

Please note that there is no light which is called a "bow light." You can put a light on the bow of your boat and you may call it a bow light, but there is no such light required in the navigation rules. Further, if you have some sort of light showing from the bow of your boat, it must not cause confusion with the required navigation lights.

Many smaller power-drive vessels show a white all-round light in lieu of other configurations. There is a specific navigation light to be shown called a sternlight but this is not to be confused with the white all-round light, which should not be called a "stern light."

It frequently occurs that people post articles in which they make various casual or incorrect references to these various lights, lamps, and lightbulbs. In the interest of providing reliable information, it is the policy of this website to conform the usage of these various terms to a more formal and specific application. If there are any questions about this practice, please contact me via email to inquire about this topic. Thank you--Jim Hebert, Moderator

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