LESSON F: AIDS TO NAVIGATION

Aids to navigation are objects placed on the land and in the water to give sailors important information about where they are and what dangers might lie nearby. The most common ones we make use of on our voyage are lighthouses, buoys, and ranges.

Most of you probably know what a lighthouse looks like. It's essentially a tower with a light on the top. The light can be one of several colors (usually white, red, or green) which will flash in a certain way. Nautical charts mark the position of lighthouses and provide information about the color and the flash pattern of the light. They also give the height of the tower. If you are sailing with a chart (and you always should!), you can check each light as you see it and compare it with the information on the chart to confirm your position. If you are lost and see a light that is flashing in a certain pattern, you can look on your chart to find the symbol for the light thatās flashing in the same color and pattern as the one you see. This can help you figure out where you are. If you see two lighthouses, you can determine your position by measuring the angle formed by your boat and the two lighthouses and drawing that angle on the chart. This method will pinpoint your exact location.

A problem encountered by sailors when sailing along a stretch of coastline is that from the perspective of the boat, maybe a mile or more offshore, the coastline tends to look like a straight line. It's often difficult to see the peninsulas and inlets or know how far they jut out and cut in. Islands off the shore may blend with the mainland behind them. Charts and aids to navigation make it easier to form a mental image of the shorelineās contours as you sail. This mental image, a detailed awareness of your surroundings, is absolutely essential to your safety and success as a sailor. Using your charts, which provide a "bird's eye view" of the region in which you are sailing, helps you develop this mental image, but it also helps to take a look around. More than once that was all I needed to do when I found myself down in the cabin puzzling over charts and trying to figure out where we were and where we should be heading.

A buoy is an object floating on the surface of the water and kept in place by a large, heavy anchor and a long chain or cable. Specially constructed buoys are used as aids to navigation. They often mark the limit of safe waters off points of land. They are also used to mark the entrances to harbors. Because the water usually gets shallower the closer you get to shore; it is sometimes necessary to dig a trench in the bottom to allow ships and boats with deep keels to enter a harbor. Such a trench, whether dug out by nature or by machines, is known as a channel. It is marked in the water by a series of buoys. These buoys are usually green on one side of the channel and red on the other. If youāre returning to the harbor (going from the sea toward the land), you keep the red buoys to starboard. Hereās how sailors remember it: Red Right Returning. So if youāre leaving the harbor, you keep the green ones to starboard. Some, but not all, buoys have lights with flashing patterns (as described in the lighthouse section), some also have bells, horns, whistles or gongs. Red and green buoys almost always have numbers: green ones have odd numbers and red ones have even numbers. The numbers run in sequence with the lower numbers found closest to the channel entrance - closer to the sea. Buoys can also be found on nautical charts.

Buoys are also used to mark passages along the Intercoastal Waterway. The rules and markings used for buoys that mark inland waterways differ from those regulating passage between harbors and the open sea.

Another aid to navigation often used in harbor areas is the range. A range consists of two fixed towers, a low one in or near the water at the waterās edge and a higher tower, usually on land, some distance behind the low one. These two towers are located so that a boat can ćline up on themä ö steer to a place in the channel where the high tower appears directly above and behind the low one. The boat then keeps on that line to stay in the center of the channel. The range does the same job as a line of red and green buoys - it helps boats stay in the channel. But whereas the buoys mark the edges of the channel, the range marks the center.

On to Lesson G: Navigational Charts -->