Get the Offline ArchiveFree lifetime updates

Ice Harvesting

6 min read

Current
🧊
Ice Harvesting
Cutting and collecting natural ice
Sub-Topics
📏
Ice Thickness Requirements
When ice is safe to work on and harvest
🪚
Cutting Tools
Saws, chisels, and scoring methods
🛷
Transport to Ice House
Moving heavy ice blocks

Harvest ice from still water, such as a pond or lake, that has frozen at least 20 cm thick, in the coldest weeks of winter, by clearing snow, scoring a grid, sawing three sides of each block and breaking free the fourth. A standard block is 30 cm x 40 cm by the ice thickness, about 27 kg at 25 cm. Never work on thinner ice, never work alone, and keep a rescue line, a ladder and an observer on the shore, because cold water disables the hands within minutes.

Part of Ice Houses and Cold Storage

Ice harvesting is the winter job of cutting natural ice from a frozen body of water and moving it to storage, so it can be used through the following summer.

One Winter’s Harvest Becomes A Summer Of Cold

Everything in an ice house depends on this short, cold, risky job. Done well, a few days on the ice yield 170-330 blocks, the amount a community of 20-30 people needs for a full summer. Done badly, it kills the crew. The work is the same: cut cleanly, move quickly, and respect the ice.

What You Need

  • A body of still water — a pond, lake or purpose-built shallow pool that freezes at least 20 cm thick — and at least 40 cm if the ice is white or opaque rather than clear. Thicker is better: 25-30 cm blocks store more cold per block, melt slower and crack less when cut. Avoid moving water, springs and inlets, where the ice is thin and weak.
  • A cold spell — sustained cold that produces clear, solid ice. Cloudy ice with air bubbles melts faster.
  • Cutting tools — see Cutting Tools.
  • Moving gear — see Transport to Ice House.
  • Rescue gear — a long light line with a float, a ladder or long plank, two ice picks per worker, dry clothes and a warm shelter on shore.
  • A crew of four to six — plus one person who stays on the shore and does nothing else.

Method: Cut The Ice

Step 1: Confirm the thickness. Drill or chop test holes in several places, not only at the shore, and read the thickness. See Ice Thickness Requirements. The ice must be uniformly thick; do not work on any area under 20 cm of clear ice, or under 40 cm of white ice.

Step 2: Clear the snow. Snow insulates the ice and slows further freezing, so shovel the working area clear.

Step 3: Score a grid. Mark lines with a saw, chisel or sharp axe. A standard block is 30 cm x 40 cm by the ice thickness, which is 20-30 cm. Larger blocks are harder to handle but melt slower.

Step 4: Cut three sides of each block. Saw along the scored lines with a crosscut saw or ice saw, whose teeth are large and coarse.

Step 5: Break the fourth side. Push or lever the block; it pops free along the scored line.

Step 6: Slide it out. Float or slide blocks along a channel to a ramp at the shore. Ice slides on ice easily. For larger operations, build a simple wooden ramp.

Step 7: Work the grid from the shore outward. Take blocks from the edge you can reach from solid ice, so no one stands on a strip about to be freed.

Worked Example: How Many Blocks

A community needs 5-10 m3 of ice.

  • Block volume, for ice 25 cm thick: 0.30 m x 0.40 m x 0.25 m = 0.030 m3.
  • Block mass at 900 kg/m3: 0.030 x 900 = 27 kg.
  • Mass for the range: 5 m3 x 900 = 4,500 kg; 10 m3 x 900 = 9,000 kg.
  • Blocks: 4,500 / 27 = about 167, and 9,000 / 27 = about 333.

So plan on roughly 170-330 blocks, and add a margin for breakage and for melt in the house.

Common Mistakes

  • Starting before the ice is thick enough — see the danger below.
  • Testing only at the shore — thickness varies across a pond, and ice near inlets or springs is thinner.
  • Leaving snow on — the ice stays thinner and weaker.
  • Standing on the block being cut — the strip drops with the person on it.
  • Warm weather halfway through — a thaw weakens the ice fast. Stop at once.
  • Harvesting from a polluted pond — see below.

Safety

Falling through ice is a race against your own hands

Cold water causes an involuntary gasp in the first minute, which can fill the lungs if the head goes under. After that, the cold takes the strength from arms and hands, so the grip needed to pull yourself out fails within minutes, long before you become hypothermic. A principle used in cold-water survival teaching is “1-10-1”, developed by Gordon Giesbrecht of the University of Manitoba: about 1 minute to get your breathing under control, about 10 minutes of useful movement, and about 1 hour before unconsciousness from cold. The hands fail first. So the rescue plan must exist before anyone steps on the ice:

  • Work in pairs at minimum, with one person on the shore watching and not working.
  • Each worker wears two ice picks on a cord around the neck or at the cuffs so they can grip the ice without using fingers.
  • Keep a throw-line with a float, and a ladder or long plank, ready on the shore.
  • Spread out. Do not bunch on the ice. See the load arithmetic in Ice Thickness Requirements.
  • If someone goes in, the rescuer reaches or throws from the shore or from a lying position; never walks up to the hole. The person in the water should kick horizontally while pulling forward on the ice, then roll away from the hole rather than standing.
  • After rescue, get the person out of wet clothes and into shelter at once. See Hypothermia.

Pond ice is not clean ice

Freezing does not reliably kill the organisms in the water. Ice from a pond with livestock, wildfowl or sewage upstream can carry pathogens. Keep harvested ice out of drinking water and out of direct contact with food unless the water source is known clean or the melt is treated. See Water Purification.

What’s Next