Ro-Ro (roll-on/roll-off) ships have one or more vehicle decks linked by stern, bow or side ramps. Types include Ro-Pax ferries carrying passengers and vehicles, cargo Ro-Ros for trucks and trailers, and PCTCs for large numbers of new cars.
In Indonesia, Ro-Pax ferries connect islands on short crossings with fast turnarounds, while cargo Ro-Ros serve inter-island logistics trucks. Short port stays demand a clear on/off order, with vehicles for the first port placed near the ramp.
Ro-Ro stability is sensitive to wide vehicle decks without transverse bulkheads. Water on a vehicle deck can move freely and create a large free surface effect, so ramp watertightness, drainage and limits on vehicle weight on upper decks are key parts of the loading plan.
Typical sizes & characteristics
| Parameter | Typical range |
|---|---|
| Types | Ro-Pax/ferry, cargo Ro-Ro, PCTC/PCC |
| Lane capacity | Inter-island ferries ~200–1,500 lane metres; large cargo Ro-Ros > ~3,000 lane metres |
| PCTC | Usually ~4,000–8,000+ CEU |
| Deck clear height | Car decks ~1.7–2.2 m; main truck decks ~4.5–6.5 m |
| Lane width | Usually ~2.8–3.1 m per truck lane |
| Ramps | Stern, bow or side; ramp SWL and axle limits separate from the deck |
| Related rules | SOLAS II-1/II-2 (special category & ro-ro spaces), CSS Code, IMO Res. A.581(14) |
Typical ranges for the vessel class, not data for any specific ship. For planning, use your vessel’s stability booklet and capacity plan.
Cargo spaces & how they are modelled
Vehicle decks by lane
Each deck is modelled as lanes with length, width, clear height and axle load limits. Vehicles are placed in sequence along each lane.
Hoistable decks
Liftable car decks change the clear height below. Their position decides which lanes can take trucks.
Internal and external ramps
Ramps are recorded with SWL, width and angle. The route from ramp to lane drives the on/off order.
DG vehicle areas
Vehicles carrying dangerous goods go only in permitted areas, often on the weather deck.
General stowage rules
Lane metres and sequence
Vehicles are grouped by destination port. Vehicles for the first port go closest to the discharge ramp.
Axle and lane loads
Axle loads are compared with deck and ramp limits. Heavy trucks go to lower decks to keep KG down.
Vehicle spacing
Side and fore-and-aft gaps are kept so crew can fit lashings and firefighting access is not blocked.
Vehicle lashing
Vehicles are secured to deck sockets using their lashing points per the Cargo Securing Manual and IMO guidelines, with handbrake and gear engaged.
Heel during cargo work
Cargo moving on and off one side can cause heel. Anti-heeling tanks and lane order keep the ship upright at the ramp.
Common mistakes & risks
- Truck weights above declared values, throwing axle loads and KG off.
- Vehicles left unlashed on short crossings and shifting when weather worsens.
- Vehicles packed too tightly for lashing and firefighting.
- Water entering the vehicle deck and creating a large free surface effect.
- Electric vehicles or vehicles with DG placed outside permitted areas.
- Heel during cargo work because lanes were filled unevenly.
Frequently asked questions
What is a lane metre?
A lane metre is a unit of vehicle lane length of a given width, typically around 2.5–3 m. Ro-Ro capacity is the total lane length, and vehicle length plus spacing determines how many units fit.
Why do heavy trucks go to lower decks?
Placing weight low reduces KG and preserves GM, while upper decks usually have lower axle load limits. Lower-deck clear height must still be checked against truck height.
Is the STOWAGE.ID Ro-Ro Planner official for stability?
No. The Ro-Ro module is the third wave and is rolling out in stages. Stability results are shore-side planning; the class-approved onboard loading computer and stability booklet remain the official reference.
Shore-side planning & decision support. The class-approved onboard loading computer remains the official reference.