A Landing Craft Tank (LCT) is a flat-bottomed vessel with an open well deck and a ramp at the bow. It can land directly on a beach, slipway or simple jetty and lower its ramp so vehicles and heavy equipment drive off under their own power. In Indonesia that ability makes the LCT a first choice for mine sites, small islands and projects without a proper port.
Because the cargo rolls on and off on its own wheels or tracks, LCT planning differs from a conventional cargo ship. The order of loading, axle loads, ramp conditions and trim when beaching are what matter most.
How LCTs are used in Indonesia
| Use | Typical cargo | Main concern |
|---|---|---|
| Mining mobilisation (nickel, coal) | Excavators, dump trucks, dozers, generator sets | Axle and track loads, lashing, ramp on a mine beach |
| Inter-island logistics | Loaded trucks, building materials, staple goods | Discharge order, vehicle height, weather |
| Construction and infrastructure | Cranes, piles, precast concrete | Long items, point loads, CoG |
| Fuel to remote sites | Tank trucks, ISO tanks, drums | Dangerous goods rules, ventilation, distance from heat |
LCT sizes vary widely, from a few tens of metres for short crossings to vessels carrying hundreds of tonnes of heavy equipment. The figures in this guide are illustrative; always use the stability booklet and ship documents.
The bow ramp and ramp load
The ramp is the weakest link in the loading chain. Watch for:
- Ramp load limit. Usually stated as a maximum vehicle mass and a maximum axle load. Only one heavy vehicle should be on the ramp at a time.
- Ramp angle. It depends on the tide, the beach gradient and the forward draft. A ramp that is too steep costs traction, grounds low vehicles and raises the risk of sliding.
- Ramp toe support. The end of the ramp must rest on firm ground. On soft sand it can sink; use steel plates or timber mats.
- Hinges and ramp wires. Inspect them before every heavy operation.
Loading order: last in, first out
An LCT usually has only one way in and out, the bow ramp. The first unit loaded ends up furthest aft and comes off last. So:
- Establish the discharge order at destination, including any multiple discharge points.
- Load the units discharged last first, at the after end of the deck.
- Place the heaviest units near midships or the LCF to keep trim under control.
- Reverse vehicles on where possible so they drive off forwards at destination.
- Leave walkways for the crew and space to fit lashings.
Axle loads and deck pressure
An LCT deck is rated for a uniform load (t/m²) and for vehicle wheel or axle loads. They are not the same thing. Tyre contact pressure is far above the uniform deck rating, so the deck plating is designed separately for wheel loads. The limits that apply are in the ship's documents.
Illustrative examples:
- 22 t excavator. Two tracks, each with about 3.6 × 0.6 m in contact, 4.32 m² in total. The average pressure is 22 / 4.32 ≈ 5.1 t/m², but it is not uniform because the load concentrates under the rollers. Two timber mats of 4.8 × 1.5 m (14.4 m² in total) bring it down to about 1.5 t/m².
- Empty 14 t dump truck. Front axle about 5 t, two rear axles about 4.5 t each. Compare every axle with the axle load limits of the deck and the ramp.
Axle load sharing can be worked out with the axle load calculator and deck pressure with the deck load calculator.
Worked example: drafts and trim
An illustrative fictional LCT: length 60 m, initial draft 1.50 m on even keel without cargo, TPC 8.0 t/cm, MTC 40 t·m/cm, LCF 28 m forward of the aft perpendicular (AP). Cargo positions are measured from the AP.
| Cargo | Weight (t) | LCG from AP (m) | Moment (t·m) |
|---|---|---|---|
| 2 empty dump trucks (loaded first) | 28 | 16 | 448 |
| 2 excavators | 44 | 28 | 1,232 |
| Wheel loader | 18 | 40 | 720 |
| 20' container of spare parts (loaded last) | 20 | 47 | 940 |
| Total | 110 | 30.36 | 3,340 |
- Sinkage: 110 / 8.0 ≈ 13.8 cm.
- Trimming moment about the LCF: 110 × (30.36 − 28) ≈ 260 t·m, by the head.
- Change of trim: 260 / 40 = 6.5 cm by the head.
- Split: aft −6.5 × 28/60 ≈ −3.0 cm; forward +6.5 × 32/60 ≈ +3.5 cm.
- Final drafts: aft 1.50 + 0.138 − 0.030 ≈ 1.61 m; forward 1.50 + 0.138 + 0.035 ≈ 1.67 m.
To return to even keel, ballast in an aft tank with its LCG 5 m from the AP (a lever of 23 m aft of the LCF) needs about 260 / 23 ≈ 11 t, adding about 1.4 cm of draft. The final trim wanted for beaching follows the ship's instructions. Many LCTs approach the beach with a slight trim by the stern so the forward draft is smaller and the propellers stay in deeper water. Sinkage and trim are covered in our guide to ship trim and draft; for quick figures use the draft and trim calculator.
Trim and stability when beaching
When the bow takes the ground, the beach carries part of the ship's weight. As a result:
- Effective stability is reduced. The ground reaction at the bow acts like a loss of GM, and it grows as the tide falls. Avoid moving heavy cargo athwartships while aground.
- The reaction changes during discharge. As a heavy unit moves forward onto the ramp, the load on the bow increases. Once it has driven off, the ship is lighter and may lift off on the rising tide.
- Tide windows. Plan beaching and departure so the ship is not left aground too long and the ramp does not become too steep.
Lashing vehicles and heavy equipment
Securing wheeled cargo follows the CSS Code, which has a dedicated annex for wheel-based (rolling) cargo, and the ship's Cargo Securing Manual. General steps:
- Apply the parking brake, leave the vehicle in gear and chock the wheels or tracks.
- Lower the bucket, blade or boom onto timber on the deck; lock the excavator swing.
- Fit chains and tensioners from the vehicle's lashing points to the deck's, in pairs forward, aft and to each side.
- Do not lash to parts not designed as lashing points, such as axles or hydraulic hoses.
- Re-tension the chains after a few hours at sea and after heavy weather.
The number of lashings follows from the unit's mass, the chain's working strength and the acceleration criteria; estimate it with the lashing calculator. Cargo-specific guides are on the excavator and vehicle pages.
Planning an LCT with STOWAGE.ID
STOWAGE.ID Vessel Stowage helps build LCT stowage plans: loading order, axle loads per position, drafts and trim for every stage. STOWAGE.ID is a shore-side planning and decision-support tool; the ship's approved stability booklet and the master's decision remain the official reference.