The ratio of the underwater volume of a ship to the volume of a rectangular block with the same effective lengths, draft and beam 
The ratio of the underwater volume of a ship to the volume of a rectangular block with the same effective lengths, draft and beam 
Related Terms 

MOLDED_DEPTHThe vertical distance from the molded baseline to the top of the freeboard deck beam at side, measured at midlength of the ship 
SEAWAYMAX VESSELThe largest vessel that can transit the locks of the St. Lawrence Seaway. Length is 226 meters (740 feet); Beam is 24 meters (78 feet); Draft is 7.92 meters (26 feet). 
CBBlock coefficient  a measure of the fullness of the form of the ship and is the ratio of the volume of displacement to a given waterline, and the volume of the circumscribing solid of constant rectangular crosssection having the same length, breadth and draught as the ship. CB= (L x B x T) The LPP is normally used in calculating the value of CB which varies with the type of ship. Fast ships Ordinary ships Slow ships 0.500.65 (fine form) 0.650.75 (moderate form) 0.750.85 (full form) 
FLOODABLE LENGTHThe length of ship which may be flooded without sinking below her safety or margin line. The floodable length of a vessel varies from point to point throughout her length and is usually greatest amidships 
LENGTH BPPThe length of a vessel along the waterline from the forward surface of the stem, or main bow perpendicular member, to the after surface of the sternpost, or main stern perpendicular member. Believed to give a reasonable idea of the vessel's carrying capacity, as it excludes the small, often unusable volume contained in her overhanging ends. 
PARALLEL MIDBODY LENGTHAlso known as PBL, PMBL, or MidBody LengthThis describes the middle side area of a tanker's or other vessel's exterior hull which is flat and usually vertical. This is usually the area of the hull that is in contact with the pier when a vessel is docked. This area is measured from aft of the bow where the hull reaches maximum beam and then proceeds aft with little variance until the hull recesses again towards the centerline near the stern. This area is the same on both sides of a vessel and therefore runs in parallel down the middle of the ship. The length of the midbody is important to know when voyage planning to determine if a vessel will safely be able to moor at a particular facility 
BALLASTAny liquid or solid weight placed in a ship to change the trim, increase the draft, or to regulate the stability 
DEADWEIGHTThe total weight in tons (2240 lb.) that a ship carries on a specified draft including fuel, water in tanks, cargo, stores, passengers, baggage, crew and their effects, but excluding the water in the boilers. It is the difference in weight between a vessel when it is fully loaded and when it is empty measured by the water it displaces. 
PMBLParallel MidBody Length  describes the middle side area of a tanker's or other vessel's exterior hull which is flat and usually vertical. This is usually the area of the hull that is in contact with the pier when a vessel is docked. This area is measured from aft of the bow where the hull reaches maximum beam and then proceeds aft with little variance until the hull recesses again towards the centerline near the stern. This area is the same on both sides of a vessel and therefore runs in parallel down the middle of the ship. The length of the midbody is important to know when voyage planning to determine if a vessel will safely be able to moor at a particular facility 
SCOPEThe ratio of length of anchor rode in use to the vertical distance from the bow of the vessel to the bottom of the water. Usually six to seven to one for calm weather and more scope in storm conditions. 
MarineProHelp 2018.