2811 HYDROGRAPHIC MANUAL PaGE 164 



2811. Different Types of Buoys 



Buoys of various types and sizes may be required in the different survey operations, 

 and various buoyancies are needed to support the anchoring gear depending on the 

 depth of water. A survey buoy may vary from an ordinary 5-gallon can or sphere, 

 or a single barrel with no superstructure, to an elaborate buoy structure constructed 

 of four standard 55-gallon barrels. There are at least seven different types of buoys 

 for ordinary use. These are: (1) Small marker buoy with no superstructure, (2) small 

 buoy with target used by launches and auxiliary vessels, (3) shoal-water buoy, (4) 

 standard one-barrel buoy, (5) two-barrel buoy, (6) three-barrel buoy, and (7) four- 

 barrel buoy. There are two types of structures for sono-radio equipment: one is a 

 wooden frame built around one or more steel barrels, and the other is an all-metal 

 construction using a single steel barrel. 



2812. Various Uses of Buoys 



In addition to their general use for the control of extensive areas in offshore surveys 

 and as R.A.R. stations, buoys are used for other purposes in connection with hydro- 

 graphic surveys. As a marker buoy, anchored at the approximate center of a shoal or 

 reef, a buoy furnishes a leading mark for a system of radiating lines for the close develop- 

 ment of the area. It is especially useful for this purpose in areas where there are no 

 ranges that can be used in running the lines. Where there are strong currents, the 

 least depth on a small shoal or rock can scarcely be found without the use of a marker 

 buoy. In unsurveyed areas a buoy may be used as a temporary aid to navigation to 

 mark a submerged rock or dangerous shoal while the survey vessel is operating in the 

 vicinity, or until it can be more permanently marked by the United States Coast 

 Guard. In R.A.R. surveys, in addition to their use for control, buoys are often used 

 as references for important positions. 



2813. Lights for Buoys 



Survey buoys must often be anchored near shipping lanes where they may be run 

 into, especially at night. Although notices of survey buoys are published in the 

 "Notice to Mariners," nevertheless losses occur. An inexpensive flashing light in- 

 stalled on a buoy minimizes such losses. Such lights are also useful for tying a long 

 dead-reckoning line to control after nightfall, and for finding buoys to be serviced or 

 picked up at night. 



Various commercial companies manufacture simple, inexpensive lighting apparatus 

 which may be adapted for use on buoy structures. The total weight of the apparatus 

 must be a minimum to avoid making the buoy top-heavy. The light should be visible 

 for a distance of at least Iji miles and should operate for a long period on a minimum 

 supply of electric current. A waterproof installation is required since the apparatus 

 is mounted outside the barrel on the superstructure of the buoy. A waterproof box, 

 containing the batteries and flasher unit, should be mounted on the lower part of the 

 superstructure but high enough above the top of the barrel so that it will not be con- 

 stantly submerged at any time. A waterproof fixture containing the light should be 

 mounted at the top of the buoy structure so as to be visible in all directions. 



A satisfactory light bulb for use in the assembly is an "Amglo Batrilite No. 75-C3R," manufac- 

 tured by the Amglo Corporation of Chicago, Illinois. It has a characteristic neon color. The bulb 



