Cave diving equipment
Eventhough its “low” season, its still very hot here in Thailand. The usually expected rains are scarce, giving for warm water and exceptionally good visibility in Song Hong Sinkhole. This specific cave course is a mixture of Sidemount and rebreather equipment. Various cave diving equipment , emergency and rescue techniques are tried and tested to see how compatible these two different dive systems really are. Chris is diving on the Pathfinder from ISC in the USA and Tate is diving on Sidemount. Ben Reymenants is diving on this new Megalodon 15 from ISC to test it out. Its the newest version and “diving like a dream”.
Other cave diving equipment they brought with them are reels and spools.
A distance line, penetration line or guide line is an item of diving equipment used by scuba divers as a means of returning to a safe starting point in conditions of low visibility, water currents or where pilotage is difficult. They are often used in cave diving and wreck diving where the diver must return to open water after a penetration when it may be difficult to discern the return route. Guidelines are also useful in the event of silt out.
A cave diver running a distance line into the overhead environment to facilitate a safe exit.
Distance lines are wound on to a spool or a reel. The length of the distance line used is dependent on the plan for the dive. An open water diver using the distance line only for a surface marker buoy may only need 50 metres / 165 feet, whereas a cave diver may use multiple reels of lengths from 50 ft (15 m) to 1000+ ft (300 m).
Reels for distance lines may have a locking mechanism, ratchet or adjustable drag to control deployment of the line and a winding handle to help keep slack line under control and rewind line. Lines are used in open water to deploy surface marker buoys and decompression buoys and link the buoy on the surface to the submerged diver, or may be used to allow easy return navigation to a point such as a shot-line or boat anchor.
The material used for any given distance line will vary based on intended use, nylon being the material of choice for cave diving. A common line used is 2 mm (0.08 inch) polypropylene line when it does not matter if the line is buoyant.
Finger spools are a simple, compact low tech alternative to reels best suited to relatively short lengths of line. They are simply a pair of circular flanges with a hole in the middle, connected by a tubular hub, which is suitably sized to use a finger as an axle when unrolling the line. Line is secured by clipping a bolt snap through a hole on one of the flanges and over the line as it leaves the reel. Line is reeled in by holding the spool with one hand and simply winding the line onto the spool by hand. Spools are most suitable for reasonably short lines, up to about 50m, as it becomes tedious to roll up longer lengths. The small, compact size, and low cost make them useful for various purposes where long line is not required. Spools may be made from any material that is strong enough and suitable for underwater service, but engineering thermoplastics are most common.
The use of guideline for navigation requires careful attention to laying and securing the line, line following, marking, referencing, positioning, teamwork, and communication.