A sled works without snow on dewy meadow grass, where friction is surprisingly low, and on mud or sand if the runners are widened enough not to sink, but on bare ground it is far more work than a wheel: dragging a 150 kg load on dirt takes about 736 N, against 44-118 N for a cart on a dirt road. Use sleds and travois off-snow for short hauls, rough ground and expedient jobs, not for regular long-distance hauling.
Part of Sled & Travois Construction
Non-snow dragging is the use of sleds and travois on grass, mud, sand or rock, where runners ride or plough the ground instead of gliding on snow.
What Dragging Costs On Bare Ground
Take a 150 kg sled load (1,472 N). The corpus puts sliding of wood on dirt at about 0.4-0.6, and the rolling resistance of a wheel on dirt at 0.03-0.08 (The Wheel). Then:
| Vehicle | Coefficient | Pull |
|---|---|---|
| Sled dragging on dirt (mid-range 0.5) | 0.5 | 0.5 × 1,472 = 736 N |
| Cart on dirt road | 0.03-0.08 | 44-118 N |
The ratio is 736 / 118 = 6 to 736 / 44 = 17. The parent article says a wheeled cart is almost always better for regular non-snow hauling over distance, and these are the numbers behind it. Sleds and travois excel for seasonal use, rough terrain and expedient construction.
Each Surface
- Wet grass: surprisingly low friction. Sleds glide well on dewy meadows. The same slipperiness removes the brake: a wet-grass slope can run a loaded sled away.
- Mud: high friction, but still easier than carrying. Widen the runners to prevent sinking.
- Sand: difficult. Widen the runners dramatically, or switch to a travois.
- Smooth rock: works if runners are padded or shod with rubber.
Why Wider Runners Help In Soft Ground
Soft ground sinks until the pressure under the runners matches what it will bear. A wider runner spreads the load. With two runners 175 cm long carrying 150 kg total (1,472 N):
| Runner width | Total area | Pressure |
|---|---|---|
| 12 cm | 2 × 175 × 12 = 4,200 cm² = 0.42 m² | 1,472 / 0.42 = 3.5 kPa |
| 20 cm | 7,000 cm² = 0.70 m² | 2.1 kPa |
| 30 cm | 10,500 cm² = 1.05 m² | 1.4 kPa |
Going from 12 to 30 cm cuts the pressure to 40% (1.4 / 3.5). Sinking also adds friction, since the runner then ploughs, so the benefit can be larger than the pressure alone suggests.
On rock, rubber trades one problem for another. Rubber on dry rough surfaces has a high friction coefficient (recalled textbook values near 0.8 for rubber on dry concrete), well above bare wood, so rubber shoes protect the runners from wear at the price of a heavier pull.
What You Need
- Wide runners or a travois for soft ground (Travois Design)
- Padding or rubber strip for rock (Runner Design & Icing)
- A drag rope or brake for wet slopes
- Spare lashing
Method: Prepare For The Surface
Step 1: Identify the surface along the route, and note the worst section.
Step 2: Widen or switch. Fit wide runners for mud and sand, or use a travois for sand.
Step 3: Shoe for rock. Pad or shoe runners that will cross bare stone.
Step 4: Reduce the load. Pull light loads on sand and mud.
Step 5: Plan the descents. On wet grass or any slope, set up a brake or hold-back.
Common Mistakes
- Relying on a narrow sled on sand — it sinks and the pull climbs.
- Hauling long distances off-snow — a cart does the same job with a fraction of the pull.
- No hold-back on wet grass — it is slippery enough to run away.
- Leaving wooden runners unprotected on rock — they wear down quickly.
Safety
Slippery slopes and heavy pulls
A load on wet grass or smooth rock can run away downhill, and a heavy drag through mud or sand strains backs and animals. Keep slopes gentle, keep out of the line below a load, and cut the load rather than force an animal through soft ground.
What’s Next
- Learn next: Terrain & Technique — choosing the vehicle
- Combine with: Cart & Wagon Construction — the better option for regular hauling