page_title: Human factors in diving equipment design
section_title: Distance lines and line markers, reels and spools
hierarchical_section_title: Human factors in diving equipment design / Distance lines and line markers, reels and spools
caption_attribution_description: English: This is an image of a cave diver running a reel from the open water into an overhead environment.
context_page_description: The underwater diver relies on various items of diving and support of equipment to stay alive and in reasonable comfort and to perform the planned tasks during a dive. The design of the equipment can strongly influence its effectiveness in performing the desired functions.
  Divers vary considerably in anthropometric dimensions, physical strength, joint flexibility etc. Diving equipment should allow as full a range of function as reasonably practicable, and should be matched to the diver, the environment and the task. The interface between equipment and diver can strongly influence functionality. Diving support equipment is usually shared by a wide range of divers, and must work for them all.
  The most difficult stages of a dive for recreational divers are out of water activities and transitions between water and the surface site such as carrying equipment on shore, exiting from water to boat and shore, surface swimming, and dressing into the equipment. Safety and reliability, adjustability to fit the individual, performance, and simplicity were rated the most important features for diving equipment by recreational divers.
context_section_description: Distance lines are used for underwater navigation where it is either essential to mark the route out of the overhead environment, or to or to return to a specific point. Lines are deployed from reels and may be left in place or recovered on the return. Reels should be easy to use and lockable to prevent unintentionally unrolling, and have sufficient friction to prevent overruns. 
  Line markers are generally used on permanent guidelines to provide critical information to divers following the line. The slots and notches provided are used to wrap the line to secure the marker in place. A simple passage of the line through the enlarged area at the base of the two slots will allow the marker to slide along the line, or even fall off if brushed by a diver. To more securely fasten the marker, an extra wrap may be added at each slot. It must be possible to fit, interpret and remove a line marker by feel in total darkness with the line under moderate tension without dislodging the line. The basic function of these markers is fairly consistent internationally, but procedures may differ by region, and between teams. The protocol for placement and removal should be well understood by the members of a specific team.
  Dive reel
  Dive spool
caption: A cave diver running a distance line into the overhead environment to facilitate a safe exit
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