Friday, February 6, 2009

Aids to Navigation

The aids to navigation depicted on charts comprise a system of fixed and floating aids that have varying degrees of reliability. Do not rely solely on any single aid to navigation, particularly a floating aid. The buoy symbol is used to indicate the approximate position of the buoy body and sinker, which secures the buoy to the seabed. The approximate position is used because of practical limitations in positioning and maintaining buoys and their sinkers in precise geographical locations. These limitations include, but are not limited to, inherent imprecision in position fixing methods, prevailing atmospheric and sea conditions, the slope and the material making up the seabed, the fact that the buoys are moored to sinkers by varying lengths of chain, and the fact that buoy body and or sinker positions are not under continuous surveillance but are normally checked only during periodic maintenance visits which occur more than a year apart. Due to the forces of nature, the position of the buoy body can be expected to shift inside and outside the charting symbol. The mariner is also cautioned that buoys are liable to be carried away, shifted, capsized, sunk, etc. Lighted buoys may be extinguished or sound signals may not function as the result of ice, running ice or other natural causes, collisions, or other accidents. For the foregoing reasons, a prudent mariner must not rely solely upon the position or operation of floating aids to navigation, but must also utilize bearings from fixed objects and aids to navigation on shore. A vessel attempting to pass close aboard always risks collision with a yawing buoy or with the obstruction the buoy may be marking.

Due to severe weather conditions and reduced vessel traffic during the winter, numerous aids to navigation lights, buoys, fog signals) are seasonally discontinued, withdrawn, or replaced by smaller aids. These changes occur at regular intervals each year. The approximate dates are specified in the Light List, the date seasonal aids are deployed may also be printed on nautical charts produced by the National Ocean Service. The actual dates the aids are deployed may be changed due to adverse weather or other conditions. Mariners should consult the Coast Guard's Local Notices to Mariners and listen to Broadcast Notices to Mariners for the latest information.

Courses should invariably be set to pass offshore aids to navigation with sufficient clearance to avoid the possibility of collision or grounding. Errors of observation, current and wind effects, other vessels in the vicinity, and defects in steering gear may be, and have been, the cause of actual collisions, or damage to these important aids to navigation. Experience shows that buoys cannot be safely used as leading marks to be passed close aboard, and should always be left well off the course whenever sea room permits. It should be borne in mind that most large buoys are anchored by a very long scope of chain and, as a result, the radius of their watch circle is considerable. The charted position is the approximate location. Under certain conditions of wind and current, they are subject to sudden and unexpected sheers, which are certain to be a hazard to a vessel attempting to pass close aboard.

Frequently Coast Guard operated aids to navigation are damaged, defaced, or destroyed by vandals. This type of activity not only creates a serious condition for the mariner, but also increases the cost to you the taxpayer. The primary targets for vandals are usually buoys and lights on structures located on the ends of jetties and breakwaters. Federal laws provide that those apprehended defacing or destroying a Federal aid to navigation shall be guilty of a misdemeanor and are subject to a fine of up to $2,500, or not less than $500, imprisonment or both plus repair cost. Those providing information leading to a conviction may be paid one half of such a fine. Report sightings of any vandalism to the your nearest Coast Guard unit.