A river landing is a bank graded to a gentle ramp and surfaced with gravel or flat stone, a floating dock is a platform on sealed drums or logs joined to the shore by a hinged ramp so that it rises and falls with the water, and a pile dock is a deck on posts driven into the riverbed where the level is fairly constant; every landing needs at least two mooring points. A boat should be moored bow or stern to the current, not broadside: a 6 m by 2.4 m scow drawing 0.125 m pulls on its lines with 600 N bow-on but 1,500 N broadside in a 2 m/s current.
Part of River Navigation & Ferry Systems
Landings and docks are the structures where boats meet the bank to load, unload and tie up, from a simple graded slope to a floating platform.
Three Structures For Three Kinds Of River
Simple landing. A cleared section of bank with the slope reduced to a gentle ramp; lay gravel or flat stones on it so that it does not turn to mud. It needs no floating parts and suits a river with small level changes or a long gentle bank.
Floating dock. A platform on pontoons (sealed drums, logs or foam blocks) connected to shore by a hinged ramp. It rises and falls with the water, which makes it the answer to a river with a large swing of level.
Pile dock. Posts driven into the riverbed carrying a fixed platform. It is practical only where the water level is fairly constant.
Mooring. Bollards (posts) or rings on the bank for tying boats, with at least two points at each landing.
What You Need
- Gravel and flat stones, or timber for a surface
- Pontoons: sealed drums or logs, with the buoyancy computed (see Barrel & Drum Raft)
- Posts and a driving method for a pile dock
- Hinges and rope for the ramp, and bollards set deep in firm ground
- A record of the river’s level range (see River Infrastructure)
Method: Build The Structure For Its Range
Step 1: Pick the site on stable bank, not on the outside of a bend.
Step 2: For a landing, grade the slope, lay gravel or stones, and edge the ramp so it does not wash out.
Step 3: For a floating dock, build the deck on its pontoons ashore, hinge the ramp to the bank and tie the dock to piles or a line so it cannot drift away.
Step 4: For a pile dock, drive the posts until they refuse further driving and brace them against the current; check by pushing hard on each one.
Step 5: Fit the bollards deep, in firm ground, with two or more at each landing.
Worked Example: Mooring Loads And Dock Buoyancy
Mooring: the scow from Loading for Stability, 6 m long, 2.4 m wide, drawing 0.125 m. Bow-on area = 2.4 × 0.125 = 0.30 m²; broadside area = 6.0 × 0.125 = 0.75 m². At 2 m/s, dynamic pressure = ½ × 1,000 × 2² = 2,000 N/m². With a drag coefficient of 1 (an assumed order of magnitude): bow-on 2,000 × 0.30 = 600 N, broadside 2,000 × 0.75 = 1,500 N, a ratio of 2.5. At 3 m/s (4,500 N/m²) the figures are 1,350 N and 3,375 N. A line rated at a 5:1 factor (see Rope Strength Testing) for the flood broadside case needs 3,375 × 5 = 16.9 kN of breaking strength per mooring system, and the bollard must hold it.
Floating dock: a deck for four people, say 300 kg, on a frame of 250 kg (assumed) needs 550 kg of net lift. A sealed 200 L steel drum of 20 kg at 50% immersion lifts 100 − 20 = 80 kg, so 550 ÷ 80 = 6.9, or 7 drums, before any margin.
Common Mistakes
- Mooring broadside to the current — 2.5 times the line load.
- One mooring point — if it fails the boat is gone; use two.
- A ramp that is too steep for carts and animals — compute its length from the level swing.
- Bollards set in soft bank — they pull out.
Safety
A taut mooring line and a flood
A line under flood load stores energy and can part or pull a bollard from the bank; stand out of the line of the rope, never wrap a line round a hand or arm, and untie boats from the dock before a flood rather than leaving them to strain. Slippery ramps and docks cause falls into cold water; see Safety & Capsizing Recovery.
What’s Next
- Learn next: Channel Marking & Aids — marking the way to the landing
- Combine with: River Cargo Operations — loading at the landing