Panamax - The maximum size ship that can fit through the Panama Canal in terms of width, length and draft generally about 80,000dwt.

Passage - A journey from one port or place to another, as distinguished from the term "voyage" which refers to a ballast and loaded passage. Also sometimes called trip.

Peak Tank - Tanks in the forward and after ends of the vessel. The principal use of peak tanks is in trimming the ship.

Per Calendar Day (Month/Year) Costs - Vessel's costs expressed as $ per day (month/year) for a calendar period during which the vessel was in service. The number of calendar days (months/years) are divided into the total costs incurred during the period.

Per Operating Day (Month/Year) Costs - Vessel's costs expressed as $ per day (month/(year) during which the vessel actually operated. It includes the costs incurred while the vessel was idle for repairs or other non-operating reasons. The number of operating days (excluding non-operating delays) are divided into the total costs.

Pilot House - The enclosed space on the navigating bridge from which a ship is controlled when underway.

Plating - The steel plates which form the shell or skin of the vessel.

Plimsoll Mark - The mark on the side of a classed vessel which indicates its safe load lines at varying seasonal conditions.

Port - The left side of a vessel when an observer is facing forward looking toward the bow. Also a door on a ship.

Port Charges - General term which includes charges and dues of every nature assessed against the vessel or its cargo in a port. It usually includes harbor dues, tug boat charges, pilotage fees, custom house fees, consular fees, etc.

Port of Registry - The port at which a vessel is registered and to which she is considered to belong. The port of registry is shown on the stern below the name of the vessel.

Port State - A state that has ports to which ships call. The port state makes regulations the calling ships must adhere to. The port state control is the controlling authority of the port state on shipping such as the coast guard or naval authorities.

Port Time (Two Types) - 1) Seabuoy to Seabuoy - The time elapsed between the vessel's passing the port's seabuoy upon entrance to re-passing it upon exit. It includes time for steaming in and out of berth, delays, hose connections, anchorage time, clearing and loading or unloading time. 2) Port to Port - Includes only time for delays, hose connections, anchorage time, clearing and loading or unloading time. Use must be consistent with voyage mileage basis.

Portable Measurement Unit (PMU) - A device designed to measure the ship's cargo when its tanks are closed to the atmosphere. It is used in conjunction with a vapor control valve.

Portable Sampling Unit (PSU) - A device designed to sample the ship's cargo when its tanks are closed to the atmosphere. It is used in conjunction with a vapor control valve.

Position Report (Position Sheets) - A summary of worldwide movements for vessel prepared by the Fleet Coordinators.

Posted Price (Contract Price) - The price for marine fuel oils which appears on a price list published by marine fuel oil (bunker) brokers.

Pour Point - The lowest temperature at which oil will remain liquid.

Premium - Surcharge over general market rate level to compensate the vessel's owner for an unusually difficult trade or to correct for an imbalance in supply/demand conditions in a given area.

Pressure/Vacuum Valve (P/V Valve) - An automatic dual purpose valve, commonly fitted in the vent lines of tankers. When in the closed position, the function of this valve is to relieve either pressure or vacuum in a tank. When in the open position it allows the passage of air or vapor into and out of the tank.

Pressure - The amount of force exerted on a unit of area by a fluid.

Absolute Pressure - The pressure referenced to a perfect vacuum as zero pounds per square inch absolute.

Atmospheric Pressure - The pressure exerted by the atmosphere. Although this pressure varies with altitude, barometric pressure and humidity, the atmospheric pressure can be defined in custody transfer contracts, or by state and federal authorities. Atmospheric pressure is most often stated as 14.696 pounds per square inch absolute.

Back Pressure - The operating pressure level measured upstream from a control valve.

Gauge Pressure - That pressure measured relative to atmospheric pressure as zero, usually designated psig.

High Vapor Pressure - A fluid which, at the measurement or proving temperature, has a vapor pressure that is equal to or higher than atmospheric pressure.

Low Vapor Pressure - A fluid which, at the measurement or proving temperature, has a vapor pressure that is less than atmospheric pressure.

Reid Vapor Pressure - The vapor pressure of a fluid at 100 degrees Fahrenheit as determined by test method ASTM D 323-58.

Static Pressure - The pressure in a fluid that is exerted normal to the surface. In a moving fluid, the static pressure is measured at right angles to the direction of flow.

Protest, Notice of - A letter issued by any participant in a voyage citing any condition with which issue is taken. This serves as a written record that the particular action or finding was questioned at the time of occurrence. For example a declaration made by the Master before a notary public or consular official when through stress of weather, there has been or the master fears that there might have been, damage to the vessel or cargo. Copies are frequently demanded by insurance underwriters in the event of a claim.

Protection & Indemnity Insurance - Mutual protection provided by an association of shipowners against liabilities not covered by insurance.

Pumproom - An enclosed area on a tank vessel which houses main and stripping cargo pumps, ballast pumps, educators and the associated piping and valves necessary for their operation.