122 



HYDROGRAPHIC MANUAL 



SCALE IN FEET 



Figure 48. — One-barrel survey buoy. 



at the top and bottom as shown in the figure. 



The lower end of the buoy is fitted with 

 suitable fixtures to which the counterweight 

 is attached. An iron washer plate is placed 

 on each side of the vertical frame and an 

 iron counterweight plate between the frame 

 members, all of which are held together by 

 two half-inch through bolts. Three holes are 

 drilled in the counterweight plate to take the 

 half-inch bolts and a three-quarter inch 

 shackle which is used to attach the coun- 

 terweight to the buoy. Any iron mass or 

 cast concrete shape of small bulk and weigh- 

 ing 180 to 200 pounds may be used as a 

 counterweight. 



A mast, at the top of which are nailed 

 cross banners three feet square, is incor- 

 porated in the superstructure of the buoy, 

 surmounted by a flatstaff' on which flutter 

 flags are tacked. The mast is nailed to the 

 cross braces at the top of the barrel and 

 through bolted by a half-inch bolt at the 

 top of the frame. 



A three-quarter inch eyebolt is bolted to 

 one of the vertical frames at a position about 

 one foot below the bottom of the barrel, and 

 to which the anchor cable is attached. A 

 rope sling is fitted to the opposite side of 

 the buoy from the eye-bolt, by which it is 

 lowered or raised. The sling is made of 3- 

 inch Manila secured to the frame above and 

 below the barrel. 



4-34 Small buoy. — The buoy described in 

 4-33 has an over-all length of about 35 feet. 

 Obviously it is not suitable for use on small 

 vessels which lack deck space and adequate 

 handling gear. For use on small vessels a 

 miniature of the one-barrel buoy may be 

 constructed using a 10- or 20-gallon barrel 

 and other parts made correspondingly light 

 for ease in handling. The buoy frame should 

 be about 16 feet long, the counterweight 

 should not exceed 35 pounds in weight, and 

 a flag staff 10 feet in length may be used. 



4-35 Buoy anchoring gear. — The ground 

 tackle used should be appropriate to the size 

 of the buoy, depth of water, and character 

 of the bottom. Small Danforth anchors are 



