Bulkheads. These are steel divisions across the vessel either transversely or fore and aft. The functions of bulkheads are:
Below bridges (BB). This term can be Found in instructions from port and charterers' agents to the ship to ensure that the ship is kept at the appropriate draft in order to ensure that it will have sufficient clearance above its highest point to pass safely below bridges (or overhead obstructions such as power cables) across a canal, channel or river in the approaches to a berth or port. To ensure the ship's clearance below bridges would be the shipowner's obligation.
Blockade. Belligerent powers have the right of blockade, i.e., the right to blockade enemy ports or coastal territory for ocean shipping by military measures.
The blockade must be respected by neutral states. Running a blockade, if unsuccessful, may entail boarding and searching for contraband and confiscation of ship and cargo.
Ballast. In order to increase the stability of ships, which have to be dispatched without cargo and to ensure that the propeller will be immersed sufficiently, say about two-thirds of its diameter, a sufficient quantity of ballast will be loaded before sailing. The quantity of ballast depends on the type of vessel, quantity of water which can be taken in the ballast tanks and also the voyage to be made. Seasonal weather conditions which may be expected on the voyage must also be considered.
Cancelling date (Laycan). This is an abbreviation for the "Laydays and Cancelling" clause in a charterparty. This clause establishes the earliest date, when the ship is required by the charterer, (e.g. "Laytime for loading shall not commence before . . .") and the latest date for the commencement of the charter (e.g. “ . . . and should the vessel's Notice of Readiness not be given before . . . ") when the charterers have the option of cancelling the charter.