NAUI Master Scuba Diver 208 Limited Visibility and Night Diving once you are together on the surface you can briefly discuss the cause(s) for your underwater separation, make plans to avoid reoccurrence of the separation, and resume your dive. Emergency separation plans will be critical in this type of diving. Buddy Lines When water conditions produce visibility near or at zero, you should consider using a buddy line (figure 8-1). A buddy line is a 1 to 2 m (3 to 6 ft) length of 1 cm (3/8 in) synthetic braided or three-strand twisted line with hand loops at each end. Floating line is preferred because it reduces the possibility of snagging objects on the bottom. Alternatively, the buddy line can have surgical tubing loops on each end that fit over the wrist. This way the hands are free for other tasks. You can also hold hands if you prefer. This will enable buddies to remain in direct contact and signal each other by a prearranged series of tugs or hand squeezes if you are holding hands. The buddy line introduces an additional potential entanglement hazard. Appropriate precautions must be taken to avoid underwater difficulties. Practicing use of the buddy line in clear water will greatly enhance your success in using the line in actual low visibility conditions. Finally, use of buddy lines in confined underwater spaces is unwise, as this increases the danger of entanglement or the line becoming snared on a fixed object. Tether Lines When a current is present and visibility is near zero, you should consider use of a tether or lifeline. Diving under such conditions is a very advanced situation and should only be attempted by properly trained divers. The tether is a line from the surface to the diver where it is secured on the body beneath all scuba equipment. A harness is commonly worn by the diver for this purpose. The line is secured by a locking carabiner or a bowline knot that will not slip. Use of tether techniques requires a fully dressed safety diver at the surface and a number of other prearranged safety procedures and line signals. Only one diver is in the water at a time. In most instances, the tethered divers are in increased jeopardy of line entanglement and, consequently, knives must be carried and located in easily accessible positions in the divers’ equipment configuration (chest or arm mounted knives are recommended). FIGURE 8-1. A BUDDY LINE ENSURES CONTACT IN LIMITED VISIBILITY
20047TC
To see the actual publication please follow the link above