Tramp ships often carry their own gear, such as booms, cranes and derricks, in case the ports they use lack suitable equipment for loading or discharging cargo. Tramp charters The tramp ship is a contract carrier. Unlike a liner, often called a common carrier, which has a fixed schedule and a published tariff, the ideal tramp can carry anything to anywhere, and freight rates are influenced by supply and demand. To generate business, a contract to lease the vessel known as a charterparty is drawn up between the ship owner and the charterer. There are three types of charters: voyage, time, and demise. Voyage charter The voyage charter is the most common charter in tramp shipping. The owner of the tramp is obligated to provide a seaworthy ship while the charterer is obligated to provide a full load of cargo. This type of charter is the most lucrative, but can be the riskiest due to lack of new charterers. During a voyage charter a part or all of a vessel is leased to the charterer for a voyage to a port or a set of different ports. There are two types of voyage charter – net form and gross form. Under the net form, the cargo a tramp ship carries is loaded, discharged, and trimmed at the charterer's expense. Under the gross form the expense of cargo loading, discharging and trimming is on the owner. The charterer is only responsible to provide the cargo at a specified port and to accept it at the destination port. Time becomes an issue in the voyage charter if the tramp ship is late in her schedule or loading or discharging are delayed. If a tramp ship is delayed the charterer pays demurrage, which is a penalty, to the ship owner. The number of days a tramp ship is chartered for is called lay days. Time charter In a time charter, the owner provides a vessel that is fully crewed and equipped. The owner provides the crew, but the crew takes orders from the charterer. The owner is also responsible for insuring the vessel, repairs the vessel may need, engine parts and food for the ship's personnel. The charterer is responsible for everything else. The main advantage of the time charter is that it diverts the costs of running a ship to the charterer. Demise charter The demise charter is the least used in