Charter Party (Lat. charta partita, a legal paper or instrument, divided, i.e. written in duplicate so that each party retains half), a written, or partly written and partly printed, contract between a shipowner and a merchant, by which a ship is let or hired for the conveyance of goods on a specified voyage, or for a defined period. A vessel might also be chartered to carry passengers on a journey. Also, a written contract between shipowner and charterer whereby a ship is hired; all terms, conditions and exceptions are stated in the contract or incorporated by reference.
A charter party is the contract between the owner of a vessel and the charterer for the use of a vessel. The charterer takes over the vessel for either a certain amount of time (a time charter) or for a certain point-to-point voyage (a voyage charter), giving rise to these two main types of charter agreement. There is a subtype of time charter called the demise or bareboat charter.
In a time charter, the vessel is hired for a specific amount of time. The owner still manages the vessel but the charterer givers orders for the employment of the vessel, and may sub-charter the vessel on a time charter or voyage charter basis.

The demise or bareboat charter is a subtype of time charter in which the charter takes responsibility for the crewing and maintenance of the ship during the time of the charter, assuming the legal responsibilities of the owner and is known as a disponent owner.
In a voyage charter, the charterer hires the vessel for a single voyage, and the vessel's owner (or disponent owner) provides the master, crew, bunkers and supplies.

Fuente: http://en.wikipedia.org/wiki/Charter-party