Linear and Charter Ships, Types, Arrangements, and Routes
Merchant ships come in two varieties, charter or tramp vessels that transport cargo based on demand and linear vessels that have fixed schedules and operate on fixed routes. Trampers include bulk carriers and tankers operating in charter markets and shipping cargo from any port to any port.
Linear vessels such as RoRo and container ships, on the other hand, have a fixed, regular routing and standard tariffs.
Charter vessels are typically hired to transport cargo over a certain route and for a specified period. The main charter types are time, voyage, and demise, with variations like contract of affreightment, bareboat yacht, and trip time. A demise charter is an arrangement whereby the charterer bears financial and legal responsibility for the vessel, including costs such as hull insurance, port expenses, crew, and fuel. This type is more common for bulk carriers and tankers.
Under a time charter arrangement, the charterer selects the route and ports and pays costs like commissions, port charges, and fuel consumed. Voyage is the third type which involves the hiring of crew and a vessel to ship cargo between a load and discharge port. Here the owner covers crew, fuel, and port costs while the charterer pays on a lump-sum or per-ton basis.
While linear ships usually have a pre-printed bill of lading, trampers use a bill of lading for chartered parties. Charterers are asked to fill in details such as description of goods, port of charge and loading, consignee and shipper, and gross weight.
Linear ships have a fixed port rotation and schedule with dates of calls. Roll-on/roll-off and container ships usually transit regular routes and ship about 60 percent of the cargo internationally. Container vessels are often used when combining intermodal transportation services is required. They carry about 90 percent of non-bulk cargo internationally and can accommodate different types of containers, including:
- Open top
- Cylindrical tank
- Side open
- Dry van box
- Flat rack
Thermal or insulated containers are typically used for long-distance shipping as they can maintain higher temperatures. The refrigerated variety is used for vegetables, fruits, and other perishable goods that require refrigeration transport. All types of containers can be transferred, transported, stacked, unloaded, and loaded.
Roll-on/roll-off ships also have a fixed schedule and routing and are designed to carry railroad cars, trailers, cars, semi-trailer trucks, and trucks. There are also variations like ROPAX, RoLo, LMSR, and ConRO. The latter is a hybrid type of vessel used to transport a mix of automobiles, oversized cargo, heavy equipment, and containers.
The main linear routes used by container and RoRo ships are to South and Central America, India, the Middle East, and the North Atlantic route linking Canada, the USA, and Europe. With charter services, there can be several alternative routes to choose from. Ship owners usually prefer the safest while charterers may go for the fastest and shortest route as a less expensive option.