Burning bright

From Ocean Navigator #61
May/June 1994
by Chuck Husick

It should be obvious to even the least experienced voyager that all vessels engaged in navigation between sunset and sunrise or during times of limited visibility must display navigation lights. These requirements are outlined in the navigation rules. A full definition of the required lights for operation in both inland and international waters is found in Part C of the Nautical Rules of the Road.

Rule 20 defines the application of the rules pertaining to lights. Rule 21 defines each of the lights, both in degree of angular visibility and position on the vessel. Rule 22 defines the required nominal range for the lights. Rule 23 defines the lights for power driven vessels underway. Rule 25 defines lights for sailing vessels underway. Rule 30 defines anchor lights.

The rules are simple and few questions should arise in their application to recreational vessels. Unfortunately, it is the installation of navigation lights on many pleasure boats that yields far from satisfactory results. Too often, navigation lights are not considered to be a priority item. However, the safety of one’s own vessel, as well as the safety of vessels one encounters, may be improved by evaluating and possibly upgrading one’s navigation lights.

The primary reason for the display of lights is collision avoidance. The type of lights that must be displayed depends on the propulsion and navigation status of the vessel. Requirements governing the minimum brightness of the lights depends on the size of the vessel. The smaller the vessel, the less demanding the lighting requirements. Unfortunately, the concept of using less powerful lights on smaller vessels can result in small craft being invisible until they approach very close to other waterborne traffic. Since night navigation can be challenging, vessels should be as well lit as possible. Although, in some situations even a well lit vessel can be difficult to see, particularly in a populated area when viewed against a background that includes many lights, both fixed and moving.

There are three common problems with the navigation lights on pleasure boats: 1) poorly designed and/or improperly installed lights; 2) lights that are too dim; and 3) improperly used lights. The fact that the rules allow smaller vessels, those that are frequently the most difficult to see, to operate with lights having the lowest required visibility does not mean that small vessels have to use low-power lights. The rules were written to allow smaller vessels to use smaller lights that consumed less electrical power. With the increasing need for electrical power even on the smallest boats and the concurrent increase in battery bank capacity, equipping even small vessels with the brighter lights required for larger vessels may make great sense.

The rules governing side lights are particularly important from a collision avoidance standpoint. The approach of one vessel toward another can create potentially critical situations. It is vital to ascertain the relative heading of the other vessel as soon as possible. The red and green sidelights provide most of the data from which to make this determination. Unfortunately, many vessels have sidelights positioned in such a way as to make both the red and the green lights visible at the same time. In some cases, the overlap is great enough to require a change of 20 or more degrees in the relative bearing of the approaching vessel before one of the lights becomes invisible. Such an installation is clearly illegal under both the Inland and International Rules of the Road. Using sideboards

Often the problem with sidelights that don’t cut off at the right angle is caused by using lights that were designed to be equipped with sideboards, but without getting the sideboards fitted. Sideboards serve to properly cut off light visibility, insuring that the confusion caused by simultaneous visibility of both sidelights won’t occur. There are navigation lights that are supposed to be satisfactory without sideboards but which do not provide the needed sharp cut off of light emission. An occasional fault in navigation light installation provides a gap in coverage, no light is visible when the vessel is viewed from dead ahead. In some installations a proper light is installed in a manner that allows gear on deck to obscure the light. This fault is more often seen on powerboats where a navigation light mounted on the side of the deckhouse is blocked by rail-mounted fender holders.

Regardless of the nature of the fault, the operator of a vessel equipped with improper sidelights should be informed of the defect. Doing so could save the operator problems with the authorities and save others from confusion and unwanted close encounters. There are models of combined bow lights (which project both the red and the green arc) that use a vertical filament lamp to insure sharp transition from one color to the other and which eliminate the confusion. These models also can reduce electrical power drain. Since this combined light can often be mounted on the bow pulpit, obstruction from gear on deck can be eliminated. Make sure that when a sail is set from the headstay it cannot cover the light.

The required stern light should be visible through an arc of 135°. On some sailing vessels, particularly those with complex transoms that incorporate boarding ladders, swim platforms, man overboard devices and the like, the stern light may be obscured over a significant part of the arc. Under some conditions of limited visibility this can cause the vessel to disappear since the sidelights’ visibility arc ends and the normal stern light arc of visibility is not available due to being blocked. Even where the initial installation was correct there are numerous instances where gear has been added to the stern that can obscure the light. On those boats with crowded transoms, a check of stern light visibility might be a good idea.

On vessels less than 20 meters in length that are propelled by sail, it is legal to use a masthead combined lantern that shows the required red, green, and white arcs. The rules also permit red over green 32 point masthead lights for sailboats. These can be shown in conjunction with the normal side lights and stern light. It is not permissible to display a tri-color masthead light in conjunction with side lights and a stern light. None of the masthead lights may be used when the vessel’s engine is being used to provide propulsion, as in motor sailing. Whenever the engine is used to propel the vessel the lights required for a power-driven vessel must be shown. One of the most common errors in the use of the tri-color lantern is to operate it at the same time as the normal sidelights and stern light. This practice can cause great confusion and is clearly illegal.

Under some conditions of limited visibility, the use of this type of lighting can cause a single vessel to be mistaken for two vessels. Some tri-color lanterns also provide a white, 360 degrees light that may be used as an anchor light. Whenever the tri-color light is turned on check to be sure that it is the tri-color that is burning, not the all-around white light, or, possibly worse, both the tri-color and the 360 degrees white light. Strobes for emegency use only

White strobe lights are occasionally seen at the masthead of sailing vessels, frequently combined with the tri-color and 360 degrees white light. Operating these lights when the vessel is underway, in other than a declared emergency, is illegal. Using the strobe light as an anchor light is also illegal. The only responsible use of such a light is to aid in identifying the vessel in an emergency situation.

When a vessel is proceeding under power it is also necessary to provide a white light on the mast, called a steaming light, that projects its light over a forward arc of 225 degrees. This light must be mounted above the sidelights. Vessels less than 12 meters in length may show a single, 360 degree white light in lieu of the white stern light and the 225 degree bow light. One common fault with bow light installation is insufficient shielding of the light from the standpoint of the helmsman. Night vision can be seriously degraded by the stray light from a bow light which is improperly shielded or which illuminates a reflecting surface visible from the helm.

Anchor lights showing a white light through 360 degrees are required whenever a vessel more than seven meters in length is anchored outside a special anchorage. Vessels less than seven meters in length are required to show an anchor light when anchored in a narrow channel or in an area where other vessels usually navigate. It is common practice to install a masthead light to serve as the anchor light. This practice, however, is of questionable value. When other vessels enter an anchorage or when a crew is moving about the anchorage in a tender their attention is usually directed at the horizon, not at a point 50 or more feet in the air. Anecdotal evidence suggests numerous near collisions caused by the limited visual impact of a small light at the top of a tall mast on the operator of a dinghy. Use of a separate anchor light, hung in the foretriangle and allowed to swing about somewhat as the vessel moves is usually more effective than a masthead light.

Regardless of the type of lights installed, a common defect is insufficient brightness, even when the manufacturer’s data sheet claims that the light fully complies with legal requirements. Virtually all navigation lights use incandescent filament lamps. Such lamps can suffer a decrease in luminous output of 30% when the supply voltage is 10% less than that for which the lamp was designed. (While the low supply voltage may extend lamp life by 400%, the purpose of installing the light is to insure being seen, not to set records for lamp life.) Avoiding voltage drop

Many of the lamps used in typical small craft lights are rated for operation from a 12.6 volt source. When a sailing vessel is operating without the use of a generator or engine-driven alternator, it is rare for the supply voltage to be as high as 12.6 volts, which represents 100% charge for most lead-acid batteries. It is more common for the battery voltage to be on the order of 12.2 volts. When this low voltage is combined with the voltage drop common in boat wiring the result is a navigation light that is too dim. Since the typical bicolor navigation light uses a 25-watt bulb, drawing a little more than two amps, assuring a voltage drop of only 1% requires the use of a pair of number 10 American wire gauge (AWG) wires in a circuit running from the battery box to the bow of the typical 40-foot sailboat (assuming a circuit length of 70 feet). While number 10 wiring may be a bit excessive, if the wiring in one’s vessel is producing an excessive voltage drop, one should consider rewiring the circuit with heavier wires. After all, since the purpose of navigation lights is for them to be seen, it is worthwhile to consider having the proper wiring to supply them with electricity.

A prudent seaman does not simply flick the running light switch and assume all is well. Good voyaging procedure involves doing an hourly boat check and part of this check should be a look at each of the running lights to make sure they are burning bright. Have spare bulbs on hand so a burned out bulb can be immediately replaced.

The general rule is that in an emergency situation anything that may result in rescue may be used, including any type of light. The purpose of the navigation lights prescribed by the rules is to prevent emergencies. Sailors need to know the rules, and be able to rapidly recognize the meaning of any series of lights. At the same time, voyagers need to insure that the lights on their vessels are the best and brightest possible. Being seen by other vessels can be the most valuable insurance against risk of collision.

By Ocean Navigator