Personnel Considerations. The supervisor of the dive must ensure that all
personnel required to make the dive have been properly trained in ice diving techniques
and are physically fit. No diver may be allowed to make the dive if, in the
opinion of the Diving Supervisor, the diver is suffering from the psychological
stress of an ice dive (anxiety, claustrophobia, or recklessness).
Dive Site Selection Considerations. The selection of the dive site will depend
upon the purpose of the dive and the geographical environment of the area (ice
thickness, ice surface conditions, etc.). Additionally, the diving method chosen,
safe access routes, shelter location, emergency holes, and exposure of divers and
required support personnel will also have a bearing on site selection.
Shelter. When ice diving is conducted, a shelter must be erected as close as
possible to the diving site to reduce the probability of frostbite and equipment
freeze-up. Normally, tents are not placed over the dive hole because they would
restrict the movement of tenders and light available to the diver. However, a windbreak
should be constructed. A shelter of modular tents and space heaters is ideal;
although precautions must be taken to ensure that the ice beneath the shelter is not
weakened. Extreme caution must be used when diving for objects, such as downed
aircraft, that have fallen through the ice; the area around the original hole may be
dangerously weakened.
Entry Hole. Proper equipment should be used to cut a suitable hole or holes
through the ice in order to leave a clean edge around the hole. Using a sledgehammer
to break through the ice is not recommended as it will weaken the
surrounding ice. The hole should be a rectangle 6 feet by 3 feet, or a triangle with
six-foot sides as shown in Figure 11-2. The triangular hole is easier to cut and is
large enough to allow simultaneous exit by two divers. Slush and ice must be
removed from the hole, not pushed under the ice surface, as it could slip back and
block the hole. To assist exiting divers and improve footing for other team
members on the ice surface, sand or burlap bags should be placed on the ice
around the hole. Upon completing the dive, the hole must be clearly marked to
prevent anyone from falling in accidentally. When possible, the pieces cut from
the ice should be replaced to speed up the refreezing process.
Navigation Lines. A weighted line should be hung through the hole to aid the
diver in retaining his bearing and sense of direction. Suspending a light at the end
of the line may be helpful, as well as attaching a series of strobe lights to indicate
depth. After locating the work site, a distance line should be laid from the
weighted line to the work site. Another method of aiding the diver in keeping his
bearings in clear water is to shovel off the snow cover on the ice around the dive
site in the form of a spoked wheel (see Figure 11-2). When the ice and snow cover
is less than 2 feet thick, the diver should be able to see the spokes leading to the
dive hole located at the center of the wheel. The wheel should have a minimum
diameter of 60 feet.
Lifelines. Diver tending lines are mandatory when diving under ice to help the
diver relocate the entrance hole. A polypropylene braided or twisted line has
proven to be the best lifeline. It has the advantage of floating up and away from
the diver and is available in yellow, white, and orange for high visibility. A
bowline or a D-ring and snap hook spliced into the lifeline is the easiest method of
attaching the lifeline to the diver. The attachment of the lifeline on both ends must
be absolutely secure. Do not tie the line to a vehicle, shovel, first-aid box, or other
portable equipment. A 4-inch by 4-inch by 2-foot board placed under the ice
several yards away from the dive hole can be used to secure the bitter end of the
lifeline (see Figure 11-2). The D-ring and snap hook allow the quickest transfer of the lifeline from diver to diver on the surface, provided the snap hooks are not
frozen shut. The snap hooks should be checked for corrosion at frequent intervals.
A wet lifeline must be kept off the bare ice to prevent it from freezing to the
surface.
Equipment Preparation. The diver must wear a distress light that should be
turned on upon entering the water. Divers should not be encumbered with unnecessary
equipment during cold water dives. Snorkels should be removed and knives
worn on the inside of the leg to help prevent the lifeline from snagging on the
diver’s equipment. Personnel, divers, and tenders must handle rubber accessories
such as masks and fins carefully; extreme cold causes them to become brittle.
