8-30 Change A
U.S. Navy Diving ManualVolume 2
another increment (roughly double the first) and makes a second sweep in the
opposite direction to avoid twisting or fouling the lifeline and air hose.
If the object is not found when the end of the circling line has been reached,
the base point (the descent line) is shifted. Each base point in succession
should be marked by a buoy to avoid unnecessary duplication in the search. If
the search becomes widespread, many of the marker buoys can be removed,
leaving only those marking the outer limits of the area.
If the diver is unable to make a full circle around the descent line because of
excessive current or obstructions, the search patterns are adjusted accordingly.
A linear search pattern (Jack-Stay) can be established by laying two large
buoys and setting a line between them. A diving launch, with a diver on the
bottom, can follow along the line from buoy to buoy, coordinating progress
with the diver who is searching to each side of the established base line. These
buoys may be readjusted to enlarge search areas.
Once the object of a search is located, it is marked. The diver can secure the
circling line to the object as an interim measure, while waiting for a float line
to be sent down.
Enclosed Space Diving. Divers are often required to work in an enclosed or
confined space. Enclosed space diving shall be supported by a surface-supplied air
system (MK 20 MOD 0, MK 21 MOD 1, and EXO BR MS).
Enclosed Space Hazards. The interior of sunken ships, barges, submarine ballast
tanks, mud tanks, sonar domes, and cofferdams is hazardous due to limited access,
poor visibility, and slippery surfaces. Enclosed spaces may be dry or flooded, and
dry spaces may contain a contaminated atmosphere.
When a diver is working in an enclosed or confined space with the
exception of submarine ballast tanks, the Diving Supervisor shall have
the diver tended by another diver at the access opening. Ultimately, the
number of tending divers deployed depends on the situation and the
good judgement of the Diving Officer, Master Diver, or Diving Supervisor
on the site.
Enclosed Space Safety Precautions. Because of the hazards involved in en-
closed space operations, divers must rigorously adhere to the following warnings.
During enclosed space diving, all divers shall be outfitted with a MK 21
MOD 1, MK 20 MOD 0, or EXO BR MS that includes a diver-to-diver and
diver-to-topside communications system and an EGS for the diver inside
For submarine ballast tanks, the divers shall not remove their diving
equipment until the atmosphere has been flushed twice with air from a
compressed air source meeting the requirements of Chapter 4, or the
submarine L.P. blower, and tests confirm that the atmosphere is safe for