Build a utility sled from two hardwood runners 150-200 cm long, 10-15 cm wide and 3-4 cm thick, with the front ends curved up at least 15 cm, joined by 3-4 cross-members 30-40 cm apart, a plank or pole floor, and a pull rope or harness at the front of both runners. Its wide runners spread a loaded sled over about 0.42 m², pressing the snow at about 2.7 kPa where a walking person presses it at about 27 kPa.
Part of Sled & Travois Construction
A basic sled is a low pair-of-runners frame with a floor, built to carry 50-100 kg when pulled by a person, with the runner fronts turned up to ride over obstacles.
Why The Runners Do Not Sink
A sled floats on snow where a foot sinks because its weight is spread over a large area. With assumed figures: two runners 175 cm long and 12 cm wide, a sled of 15 kg and a load of 100 kg.
- Runner area = 2 × 175 cm × 12 cm = 4,200 cm² = 0.42 m²
- Total weight = 115 kg × 9.81 = 1,128 N
- Pressure = 1,128 N / 0.42 m² = 2,690 Pa, about 2.7 kPa
A 70 kg person on one boot sole of 25 × 10 cm = 250 cm² (0.025 m²) presses with 687 N / 0.025 m² = 27,500 Pa, about 27 kPa. The sled presses the snow about ten times more gently than the puller does, so the puller, not the sled, is what breaks through (Snow Conditions on snowshoes).
Bending The Upturned Front
The parent article upturns the runner fronts by at least 15 cm, by steam bending or by soaking and clamping over a form. How sharp is that? If the runner rises 15 cm over a 30 cm run, tangent to the ground at the start, the bend radius is R = (run² + rise²) / (2 × rise) = (900 + 225) / 30 = 37.5 cm. For a 3.5 cm thick runner, R / t = 37.5 / 3.5 = 11. Steam Bending advises a metal strap when the radius is under 15 times the thickness, so this bend needs steam and a strap. Spread the same rise over a 50 cm run and R = (2,500 + 225) / 30 = 91 cm, R / t = 26, which a soaked runner can take on a form without a strap.
What You Need
- Two runners: hardwood boards or split logs, 150-200 cm long, 10-15 cm wide, 3-4 cm thick
- 3-4 cross-members and floor planks or poles
- A bending form and steam or soaking water
- A pull rope or harness
- Lashing or pegs and an auger (Materials & Lashing)
Method: Runners, Frame, Floor
Step 1: Shape the runners. Plane or scrape the undersides smooth (Runner Design & Icing).
Step 2: Curve the fronts. Steam-bend, or soak and clamp over a form, to at least 15 cm of upturn so the sled rides over obstacles.
Step 3: Join the runners with 3-4 cross-members at 30-40 cm spacing.
Step 4: Lay the floor across the cross-members.
Step 5: Attach the pull rope or harness at the front of both runners, with a bridle so both are drawn together.
Dimensions For A Utility Sled
- Length: 150-180 cm
- Width: 60-80 cm
- Runner height: 5-8 cm above ground
- Capacity: 50-100 kg by person, 200-400 kg by horse
Common Mistakes
- Narrow runners — they sink in soft snow; at 12 cm width the pressure is 2.7 kPa for the example above, and halving the width doubles it.
- Too little upturn — the front digs into drifts and ruts.
- A rope on one runner — the sled yaws.
- Overtight pegging with green wood — the joints loosen as the wood dries.
Safety
Steam-bending and sled loads
Steam burns when the box is opened toward you, and a strap-bent runner can spring back: see Steam Bending. A loaded sled moving downhill can overrun the puller and cannot be stopped by hand: keep slopes gentle and use a brake or a rope held from behind.
What’s Next
- Learn next: Runner Design & Icing — the bottom surface
- Combine with: Harness & Gang Line — hitching dogs to the rope