*** Flat Ice Travel & Rescue *** Thu Jan 5 09:50:55 1995 Message : #20480227 From: Struan Gray Address : struan.gray@sljus.lu.se Group : Usenet.rec.backcountry Subject : Re: Frozen Lake Safety, info/FAQ??? I once met some people who (voluntarily) took part in experiments to see how best you could survive if you fell though ice when wearing full backpacking equipment and skis. Markus listed the main tricks (carry something sharp to help you climb out, loosen ski bindings and rucksack waistbelts, know how to warm up again once out) but one non-obvious extra point emerged from the experiments which was that you should force yourself to remember to breath. In the experiments (method: cut hole in ice, jump in, wait until about to go under, get hauled out) they found that most people were unable to swim after two to three minutes, although some individuals lasted as long as ten. In all cases, the subjects gasped and spluttered in the way known to anybody who has stepped into a cold shower unawares. The watching docs came up with the idea that the lack of proper breathing contributed to the subjects' rapid physical deterioration. Naturally a followup experiment was performed. The subjects were all coached to concentrate explicitly on their breathing and force themselves to take deep breaths, before being chucked back in the hole. Second time around they all lasted 15 minutes or more. Useful tip. A further musing: one reason why surface ice is stronger than you might at first imagine is that it is supported by the water underneath. Apart from the obvious conclusion that you should avoid areas where the water level might drop suddenly, such as near hydroelectric projects, there are also interesting effects which can arise if you start to travel at speeds comparable to the surface waves of the whole structure, easily possible in a skidoo, car or McMurdo resupply Hercules. Then you create a bow wave in which the ice is subject to much greater stresses than those needed to support your static weight. Travel too fast and you create a nice little hole right in front of your vehicle. Whoops! Struan Gray ------------- Sun Jan 22 16:42:43 1995 Message : #21143676 From: Markus Bjorksten Address : mfb@fyslab.hut.fi Group : Usenet.rec.backcountry Length : 1775 words Subject : Weak ice safety Org. : Helsinki University of Technology, Finland Here is a revised version of an article I sent a few weeks ago. Since that I among others had to 'rescue' a victim. Fortunately it was nothing very serious. A somewhat over waist-deep ditch, which was, a bit surprisingly, not noted in the moonshine until the ice cracked under an unlucky hiker. Even this situation would have been difficult had she been alone since she had no spare clothing. I have made no big changes to the list, but added some stuff. I am still no authority on the subject, so I make a WARNING about that there may be dangerous errors and omissions below. Markus Bjorksten ------------------------------------------------------------------------- WEAK ICE SAFETY First rule: If in doubt, don't go! SAFETY EQUIPMENT: [I explicity decline to give a list of 'recommended' equipment as the level required depends so much on the situation. Here is some commonly used equipment:] - Ice studs (Spikes protruding 3cm from two sturdy floating handles. Handles are connected with rope behind the neck. The rope should unwind to such length that studs can be held at straight arm length. Studs are carried ready for use, close to the chin with the spikes covered. [The translated word 'ice stud' may be wrong.]) Ice studs are very important, especially if there is no snow (to help provide grip) on the ice. - Spare clothing: Warm spare clothing packed to be waterproof (possibly including sleeping bag, trash bags are good for packing.) Hint: use plastic bags between wet boots and dry socks. - Ice spear: Relatively blunt spear/pole for measuring ice thickness/strength (mark lines for measuring the ice thickness). Special poles with metal tips are made for this purpose. The length should be about to your shoulder. - A 'J'-formed rod for measuring ice thickness through a hole. - Axe or other tool for making measuring holes in the ice. - Warm drink with sugar. Keep in a steel thermos bottle. - Whistle (plastic, not metal). - Rescue rope: 25m of throw rope. Attach a soft floating weight and handle at one end, (made for small vessel safety), ready to throw over the shoulder). The other end should be well attached to the thrower. - Flotation vest/clothes. - Wet suit (preferably 5mm thick or more). - Rescue suit eg. a totally waterproof suit of Gore-Tex (for small vessel safety). Be careful not to puncture the suit with ice etc. as they have a limited life (leakages are due to wear). Separate flotation gear is recommended and warm clothing underneath is essential. The 'ultimate' in thin ice safety. - Hypothermia bag (a special vapour barrier bag for soaked persons, some can be worn standing, and permit walking while being worn). - Skis: Keep the bindings open. Skis reduce ground pressure, but make rescue more difficult if the bindings are closed. Also, skis allow you to go on thinner ice before falling: but are more difficult to rescue. - Ski poles, knife, large ordinary spikes: Can be used as an inferior susbstitute for ice studs. Do not keep the knife in hand (esp. without a cord), since it is easily lost and may cause injury when falling. - Backpack: Pack waterproof (closed plastic bags) to increase buoycancy. Closed waistbelts helps a lot to provide flotation. (But may be difficult to open if needed ie. one cannot get out with (a large?) backpack on.) - Company: Other person(s) can make rescue much easier. It is much safer not to go alone. - Identification plate to ease later identification of a rotten body :-) BASIC ICE TYPES: - Autumn ice ('steel ice', uniform, tough, blue/grey). Noisy but considered safe if 5cm thick. Even 3cm usually supports but safety margin is then dangerously narrow. (Noise does not necessarily indicate too weak ice. Noise and cracks due to tensions in the ice are quite normal.) - Spring ice. Porous, whitish, brittle, refrozen ice/snow. Carries walker by buoycancy, not by strength. No thickness rule for 'safe' ice. No noise and breaks without warning. - Actual ice may be a mixture of layers of the ice types above and snow and water. RELATIVELY DANGEROUS SPOTS: Even in the middle of winter some spots may have weak ice. - Currents weaken ice: - in rivers, esp. where the current is strong (rapids, at steep bank, outer bank in turns, boulders). - current can pull a victim under the ice, lethal! - where river, ditch, cloac etc enters/leaves a lake. - where bottom currents surface etc (these often cannot be seen). - in narrow passages, close to capes. - in shallow areas of a deeper water. - close to dams. - springs. - ditches, creeks. - Cracks, an open crack reduce the supportable weight to 40% of that supported by the original steel ice, two open crossing cracks: reduces the supportable weight to 25%. - Discontinuities in ice structure. - Close to open water, boat fairways. - Snow drifts/piles (slows/stops freezing underneath, weight, hides possible holes from sight, but snow crust (spring) can support), snowdumps. - Water on ice (weight strains the ice). - Night, low visibility. - Close to objects punctating ice; stones, weed, piers etc., esp. in spring when these get warmer than the snow (darker & more absorbing than snow). - Beachline; melts early in spring (esp. south slopes), does not freeze well early at 'soft' bog beaches. - Far from shore (ice comes later (deep, waves) and wind breaks ice). - Warm water weakens ice: - springs. - cloacs. - nuclear power plants. - Sea: ice comes later, stays shorter and is more brittle (salt, wind, large, deep). - Under bridges (the ice is weakened by reflected heat) - Water level adjustments (air under ice, cracks, water on ice) - Hydroelectric power plants, dams, etc. - Holes, esp. large snow-covered and unmarked. For fishing swimming etc. - Marks (twigs etc) may signal holes in ice. RELATIVELY STRONG ICE: - Gulfs without ditches or weeds etc, shallow water (but not a shallow area in the middle of deeper water), small ponds, no current. Longish periods of cold weather with little or no snow and wind results in thick steel ice. MOVEMENT: - High speed travel is dangerous (skating), as one can get far from strong ice before falling through. - Check ice thickness/strength at short intervals and always when the ice type changes. Hit spear onto the ice, if it goes through: Danger! Measure thickness and determine the ice type. It is good to sometimes measure ice thickness (make a hole with axe or other tool) even if spear does not go through. - Do not go close to your companions (> 10m (?)). - Move 'softly', separate feet and arms widely, creep, crawl or roll to reduce ground pressure. - Usually following fresh tracks is relatively safe, but previous mover may have cracked (and weakened) the ice. - If crossing narrow dangerous spots, increase speed and glide over with skis or skates (if possible). - Use a safety rope between the group members (>10m (?)) between hikers, with a double bowline under the arms). - Pull the backpack or ahkio (sled) with a rope, or tie to the safety line between the hikers and pull along the ice. HOW TO RESCUE WHEN THE ICE BREAKS: - Lie flat on the ice, move away from the hole and creep back towards the direction you came from. If you fall through: (other techniques exist too) - Shout. - Keep calm. - Put the pole (or ski pole) across the hole to support you. - Get your skis off. (kick if your bindings are open). - Turn back into the direction you came from. - Throw the rescue rope to rescuers. Rescuers help you by pulling while you use studs etc. to get up. - Break the ice with your fists and elbows until you encounter strong ice. - If you are alone and not close to habitation, your backpack and skis must be rescued as well. First push these up onto the ice as far as you can. Alternatively your backpack can be kept on when getting up (it works as flotation aid), this requires more strength but is faster. Skis and backpacks float, some ski poles do not. - Possibly put the pole across the hole to strengthen the edge. - Use ice studs or ski poles (both) to pull yourself onto the ice. Hit as far as you can, always secure grip with one stud. Kick with your feet, 'swim' horizontally onto the ice. Possibly push with your feet from the opposite edge of hole. - Without studs etc. use your hands to push up (like push ups) and then carefully fall forward. Repeat. Keep body horizontal by kicking (swiming) with your feet. - Creep/roll on the ice in the direction you came from along your tracks. - When the ice gets thicker, continue by crawling on all fours. - Stand up only when the ice is certainly strong enough. Wet clothing weighs and you are not wearing skis know. - Soft snow absorbs water; roll in soft snow. - Get warm dry clothing, fire and housing etc fast. If you cannot get up: [Only if you have lost your strength attempting self rescue and cannot get up by yourself] - Keep a hold on the ice or possible flotation gear. - Keep shouting and blowing your whistle for help. - Do not move unnecessarily (this cools you due to water movement). - Try to keep to a fetal position if possible. If your companion goes through: [Rescue of a victim can be a significant risk to the rescuer] - Shout. - Keep calm, reassure victim. - Take a rope, skipoles, ski, pole, jacket, scarf or anything 'longer than your arm'. - Approach the victim from the direction she came from. - Creep/roll on the ice to reduce ground pressure as you approach the victim. - Grip ice with the stud in one hand and use a rope etc. to pull up the victim with the other. - Be careful that you are not pulled into the hole too. Danger! - If several rescuers are available, a chain can be formed. - Treat for hypothermia, drowning etc. correctly (not discussed here). - Lend dry clothing, take the victim to a warm place etc. If you both go through: - One helps the other to get up first by pushing them out of the hole. - The one out of the hole helps the other by pulling them out too. - Otherwise rescue as described in the previous cases. (Markus Bjorksten)