In just minutes, fog, heavy rain, and in some cases even snow can reduce visibility on the water to just a few yards, leaving boaters confused as to their position, and what obstructions may be around them. At sunset recognizable shoreline features disappear, often replaced by unfamiliar and confusing lights that leave many boaters disoriented and unsure how to get safely home. At night, depth perception and color recognition are impaired. Other boats may be operating without required navigation lights, in violation of federal law requiring navigation lights from sunset to sunrise and during periods of restricted visibility. Without lights they can be very difficult to see in the water.
Operating a boat when visibility is restricted raises the risk of hitting fixed objects in the water and colliding with other boats. That’s why it’s prudent to lessen your risk by taking preventive action that includes slowing to a safe speed, energizing your navigation lights, and sounding the appropriate sound signals for your vessel type, as required by the Navigation Rules, available online through the Coast Guard Navigation Center at www.navcen.uscg.gov. It is also important to post responsible lookouts who will use all of their senses – sight, sound, even smell – to determine what lies ahead in time to avoid an accident. A lookout should scan 360 degrees, as accidents at night can occur when a vessel is overtaken from behind.
Illustrations and descriptions of the specific lighting requirements for every type of watercraft are provided in the Navigation Rules, which should be your primary source of information. Briefly speaking, however, these are the navigation lights required for recreational vessels:
• Sidelights: These red and green lights are visible to another vessel approaching from the side or head-on. The red light indicates a vessel's port (left) side; the green indicates a vessel's starboard (right) side. These lights are also referred to as combination lights when displayed on a vessels bow, or, in the case of sailboat, when on top of the mast.
• Stern Light: This white light can be seen from behind or nearly behind the vessel.
• Masthead Light: This white light shines forward and to both sides and is required on all power-driven vessels. Since a masthead light must be displayed by all vessels when under engine power, the absence of this light indicates a sailboat under sail.
• All-Round White Light: On power-driven vessels less than 39.4 feet in length, this light may be used to combine a masthead light and stern light into a single white light that can be seen by other vessels from any direction. This light also serves as an anchor light when sidelights are extinguished.
Remember that displaying the proper navigation lights at night and during periods of restricted visibility is only half of the issue. You also need to be able to identify and interpret the navigation lights you see on other boats in the vicinity. This can help you determine if you are in an overtaking, meeting or crossing situation.
After dark, the painted color patterns of Aids to Navigation – the buoys and beacons that mark safe water and hidden dangers and tell boaters their position in relation to land – are generally replaced by a configuration of lights. You will need to be able to identify these navigation aids to help determine your position and stay out of dangerous situations. To get an accurate position you will need to use a nautical chart. The chart will show you the position of the Aids to Navigation, their light characteristics and what landmarks you may be able to see and identify once the sun goes down.