Draft (hull) in the context of "Ballast tank"

A submersible bridge is a type of movable bridge that lowers the bridge deck below the water level to permit waterborne traffic to use the waterway. This differs from a lift bridge or table bridge, which operate by raising the roadway. Two submersible bridges exist across the Corinth Canal in Greece, one at each end, in Isthmia and Corinth. They lower the centre span to 8 metres below water level when they give way to vessels crossing the channel.

The submersible bridge's primary advantage over the similar lift bridge is that there is no structure above the shipping channel and thus no height limitation on ship traffic. This is particularly important for sailing vessels. Additionally, the lack of an above-deck structure is considered aesthetically pleasing, a similarity shared with the Chicago-style bascule bridge and the table bridge. However, the presence of the submerged bridge structure limits the draft of vessels in the waterway.

A pontoon bridge (or ponton bridge), also known as a floating bridge, is a bridge that uses floats or shallow-draft boats to support a continuous deck for pedestrian and vehicle travel. The buoyancy of the supports limits the maximum load that they can carry.

Most pontoon bridges are temporary and used in wartime and civil emergencies. There are permanent pontoon bridges in civilian use that can carry highway traffic; generally, the relatively high potential for collapse and sinking (e.g. due to waves and collisions) and high continuous maintenance costs makes pontoons unattractive for most civilian construction. Permanent floating bridges are useful for sheltered water crossings if it is not considered economically feasible to suspend a bridge from anchored piers (such as in deep water). Such bridges can require a section that is elevated or can be raised or removed to allow waterborne traffic to pass. Notable permanent pontoon bridges include the Hood Canal Bridge and the Nordhordland Bridge.

The Singapore Strait is a 113 km-long (70 mi), 19 km-wide (12 mi) strait between the Strait of Malacca in the west and the South China Sea in the east. Singapore is on the north of the channel, and the Indonesian Riau Islands are on the south. The two countries share a maritime border along the strait.

It includes Keppel Harbour and many small islands. The strait provides the deepwater passage to the Port of Singapore, which makes it very busy. Approximately 2,000 merchant ships traverse the waters on a daily basis in 2017. The depth of the Singapore Strait limits the maximum draft of vessels going through the Straits of Malacca, and the Malaccamax ship class.

A catamaran (/ˌkætəməˈræn/) (informally, a "cat") is a watercraft with two parallel hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is required. Catamarans typically have less hull volume, smaller displacement, and shallower draft (draught) than monohulls of comparable length. The two hulls combined also often have a smaller hydrodynamic resistance than comparable monohulls, requiring less propulsive power from either sails or motors. The catamaran's wider stance on the water can reduce both heeling and wave-induced motion, as compared with a monohull, and can give reduced wakes.

Catamarans were invented by the Austronesian peoples, and enabled their expansion to the islands of the Indian and Pacific Oceans.

The head of navigation is the farthest point above the mouth of a river that can be navigated by ships. Determining the head of navigation can be subjective on many streams, as the point may vary greatly with the size or the draft of the ship being contemplated for navigation and the seasonal water level. On others, it is quite objective, being caused by a waterfall, a low bridge that is not a drawbridge, or a dam without navigation locks. Several rivers in a region may have their heads of navigation along a line called the fall line.

Longer rivers such as the River Thames may have several heads of navigation depending on the size of the vessel. In the case of the Thames, that includes London Bridge, which historically served as the head of navigation for tall ships; Osney Bridge in Oxford, which has the lowest headroom of any bridge on the Thames that generally restricts navigation to smaller vessels such as narrowboats and cabin cruisers, and the long reach above St John's Lock, the first lock downstream of the river’s source, on the outskirts of Lechlade, where the river can become treacherously narrow and shallow for anything but small motorboats and human-powered vessels.

A galley is a type of ship optimised for propulsion by oars. Galleys were historically used for warfare, trade, and piracy mostly in the seas surrounding Europe. It developed in the Mediterranean world during antiquity and continued to exist in various forms until the early 19th century. It typically had a long, slender hull, shallow draft, and often a low freeboard. Most types of galleys also had sails that could be used in favourable winds, but they relied primarily on oars to move independently of winds and currents or in battle. The term "galley" originated from a Greek term for a small type of galley and came in use in English from about 1300. It has occasionally been used for unrelated vessels with similar military functions as galley but which were not Mediterranean in origin, such as medieval Scandinavian longships, 16th-century Acehnese ghalis and 18th-century North American gunboats.

Galleys were the primary warships used by the ancient Mediterranean naval powers, including the Phoenicians, Greeks and Romans. The galley remained the dominant type of vessel used for war and piracy in the Mediterranean Sea until the start of the early modern period. A final revival of galley warfare occurred during the 18th century in the Baltic Sea during the wars between Russia, Sweden, and Denmark. In the Mediterranean, they remained in use until the very end of the 18th century, and survived in part because of their prestige and association with chivalry and land warfare. In war, galleys were used in landing raids, as troop transports and were very effective in amphibious warfare. While they usually served in wars or for defense against piracy, galleys also served as trade vessels for high-priority or expensive goods up to the end of the Middle Ages. Its oars guaranteed that it could make progress where a sailing ship would have been becalmed, and its large crew could defend it against attacks from pirates and raiders. This also made it one of the safest and most reliable forms of passenger transport, especially for Christian pilgrims during the High and Late Middle Ages.

Malaccamax is a naval architecture term for the largest tonnage of ship capable of fitting through the 25-metre-deep (82 ft) Strait of Malacca. Bulk carriers and supertankers have been built to this tonnage, and the term is chosen for very large crude carriers (VLCC). They can transport oil from Arabia to China. A typical Malaccamax tanker can have a maximum length of 333 m (1,093 ft), beam of 60 m (197 ft), draught of 20.5 m (67.3 ft), and tonnage of 300,000 DWT.

Similar terms Panamax, Suezmax and Seawaymax are used for the largest ships capable of fitting through the Panama Canal, the Suez Canal and Saint Lawrence Seaway, respectively. Aframax tankers are those with a deadweight tonnage of 80,000 to 120,000.