On/Off hire survey. When a ship commences a time charter it is said to be "delivered" to the Charterer.

Off hire. In a time charter the charterer has the obligation to pay hire for the Ship continuously during the charter period at the agreed rate.

Economic speed or Optimum speed. Several factors are considered when determining the economic speed of a vessel.

Off hire clause. The Off hire clause. and other clauses in the time charterparty specify the circumstances which cause the ship to become off hire and payment of hire to be reduced.

Open registry. This is a system whereby a country may allow ships to be registered there and fly the country's flag without the real owner having any definite connection with the country. The phrase is similar to "Flag of Convenience" but that phrase is more often used in a critical manner, for example by the ITF.

Open charter.A charterparty in which neither the nature of the cargo nor the ports of destination are specified is called an "open charter".

Once on demurrage, always on demurrage. If the charterers fail to ensure that cargo operations are completed within the agreed laytime, they have breached the charter.

Optional cargo clause. In a time charterparty, such as in the New York Produce Exchange form, the vessel is

Of 24 hours. Such an expression may be used in the description of a "working day" and taken by charterers to mean that it comprises 24 hours, which may not be consecutive.

Order bill of lading. Most of the bills of lading used in international trade and shipping are of this type. When a bill of lading does not contain the name of the consignee it is not a named bill of lading.

Overstowing. A clause in a charterparty may allow either the charterer or the owner to load cargo over the original cargo, if there is available space and deadweight capacity available. However, overstowing may cause problems with the time for discharge of the original cargo as occurred in the case of The Mexico I, 1990.  Overstowing by the owner may also lead to claims if the cargo beneath is damaged.

Open cover. Here the underwriter undertakes to insure all shipments over a specified period.

Down by the head - Down by the stern - On even keel.

These expressions mean:

Overside delivery clause. Sometimes consignees of parcels are granted the option of taking delivery of the goods by their own lighters.

Other mutual insurance. A mutual protection is no longer exclusive to shipowners. Other cover for liability can be mutual, for example, for professional negligence by shipowners or the liability of freight forwarders.