{{unreferenced, date=September 2015 Penguin 2

A semi-submarine (semi-sub) is a surface vessel that is not capable of diving, but has accommodation space below the waterline featuring underwater windows. The watercraft is similar to glass-bottom boats, but with deeper draft. Both types of boats are mainly used to provide sight-seeing trips for tourists in clear, calm, and often shallow, waters.

Design

The most common design is similar to a small

ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguishe ...

. The passenger cabin is deep within the hull, a few meters below the waterline. The cabin is equipped with large underwater windows, so the passengers can observe the marine environment that is passed during the voyage. There are significant engineering differences between a true submarine and a semi-submarine. Submarines are human-occupied

pressure vessel A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure. Construction methods and materials may be chosen to suit the pressure application, and will depend on the size o ...

s subjected to high external pressure, while semi-submarines are only subjected to the same pressures as other surface vessels of similar draft operating in similar conditions. As the

hydrostatic pressure Fluid statics or hydrostatics is the branch of fluid mechanics that studies the condition of the equilibrium of a floating body and submerged body " fluids at hydrostatic equilibrium and the pressure in a fluid, or exerted by a fluid, on an i ...

close to the water surface is relatively low, the viewing windows can be large. In some designs, the windows enclose the majority of the immersed hull. Passengers can climb up from the submerged cabin to the unsubmerged deck level at any time. Since the semi-sub interior is always open to the atmosphere, no special measures must be taken to assure a supply of breathable air to its occupants.

Use

Semi-submarines can be used for

research Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness t ...

, but they are most commonly used in the

tourism Tourism is travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours. The World Tourism Organization defines tourism ...

business. However, large tourism-oriented semi-submarines should not be confused with

narco-submarine A narco-submarine (also called a drug sub or narco sub) is a type of custom ocean-going self-propelled typically semi-submersible (sometimes fully-submersible) vessel built for smugglers. Newer submarines are 'nearly-fully' submersible to be ...

s which are smaller home-made semi-submarines used to

smuggle drugs The illegal drug trade or drug trafficking is a global black market dedicated to the cultivation, manufacture, distribution and sale of prohibited drugs. Most jurisdictions prohibit trade, except under license, of many types of drugs through ...

Legal status

Semi-submarines do not have an international classified status. Their operating range from the native port might be limited by the local authorities.

External link

Turkey's first semi-submarine
Boat types Nautical terminology Water transport Tourist activities Submarines by type Pressure vessels

Design

Use

Legal status

See also

External link