Section 2.2: Ship Types Flashcards
What are the different ship types?
- Bulk Carriers.
- Container Ships.
- General Cargo Vessels.
- Tankers, Gas Carriers and Chemical Tankers.
- Passenger Vessels.
- Roll On Roll Off Vessels.
- Offshore Vessels and Tugs.
- Special Purpose Vessels.
What are the World Merchant Fleet statistics?
- 93% of Global Shipbuilding occurred in China, the Republic of Korea and Japan in 2019.
- Half of the world fleet is owned by Asian Companies.
- 16% of the global fleet carry capacity is registered in Panama.
In 2019, the world commercial fleet grew by 81 million DWT.
There are three basic principles underlying the hull structure design that must be kept forefront of the designer’s mind.
- There must be separation of accommodation spaces from the remainder of the vessel by thermal and structural boundaries.
- Containment detection and extinction of fire that may occur in one or more spaces of the vessel.
- Protection of the means to escape if required.
Accommodation has been designed to have spaces to be constructed in a manner that is approved by SOLAS regulation. Three methods may be considered in the design phase of the vessel.
Method 1: The construction of internal divisional bulkhead to be fitted and lined with fire retardant material.
Method 2: Installation of an automatic sprinkler system with a fire alarm system for the detection and extinction of fire in all spaces.
Method 3: The subdivision of the spaces by fire-restricting divisions with and automatic fire detection system and the use of combustible materials used in the internal lining of the spaces is to be restricted to an absolute minimum. The machinery spaces require the use of special detection and extinction system, which may include the use of chemical, CO2 or water mist systems.
Types of bulk carriers.
New vessels of over 150 metres in length are required to be double-hulled.
Bulk carriers come in generally accepted sizes based on the various trades they are intended to service.
- Handysize Bulkers / Handymax, range of 25-50,000 DWT. This vessel has a loaded draft of 12 metres and is able to access the shallow water ports of the world, particularly the Americas and West African ports. The handysize bulker is is versatile and able to self-discharge. In Australia, these vessels have been used to carry some high-valued cargo such as alumina and iron pellets to smelters and steel mills.
- Panamax Bulkers, range of 50 - 80,000 DWT and were primarily designed to access the Panama Canal. They were originally required to be less than 289.5 metres in length and have a maximum beam of 32.3 metres and a draft of less than 12 metres. The modification to the locks in Panama Canal now permits larger vessels to transit, and this is now up to 366 metres in length and a maximum breadth of 55 metres and a draft of 15.2 metres.
- Cape Size Bulkers, range of 100 -180000 DWT the loaded draft of 17 metres have been designed for the carriage of iron ore and coal. These vessels are generally gearless and rely on shore-based loading and unloading facilities.
Details on container ship
- Double hull design.
- Installation of Automatic Heeling Systems that will keep the vessel upright within a small tolerance.
The benefit is to avoid the containers wedging in the hold cells. Some of the container vessels have been configured to carry a combination of containers and bulk cargo. This will mean that the hold arranged for bulk cargo will not be fitted with cells.
Details on general cargo ships
- ‘special build for purpose’.
- Constructed with cranes that can handle the combined weight of a 20-foot container at least. They can sometimes be classified as a ‘Break Bulk’; some of the GC vessels can handle bulk cargo such as grain and fertilisers.
Details on tankers, gas carriers and chemical tankers
The transverse frames were then joined using longitudinal frames to which the shell plating was attached.
The system of framing tankers using the Isherwood System was used extensively until the advent of larger vessels. The longitudinal framing system was combined with transverse framing, that became the basis of the framing system for tankers from the early 1970s.
Combination framing is now used as the method for framing tankers. The need to be doubleskinned incorporates the type of structure on all tankers.
The effort in retrofitting a double skin was disregarded due to the loss of cargo capacity. The decision of refitting the cargo space was also not a successful approach. In the main, all tankers are now.
Tankers were classified by type and trade.
Product Tankers, In the case of oil tankers, range of 10-60,000 DWT.
Panamax Tankers were originally 60-78,000 DWT; now, this has been increased since the canal
was widened and lengthened.
Aframax Tankers 80-120,000 DWT brought about by the limitations of African port limitations.
Suez Max Tankers 120-200,000 DWT to allow these large vessel to transit the Suez Canal.
VLCC are very large crude oil carriers, too large to access most ports and terminals and were loaded and discharged either by lighter or submarine oil connections. These were 200-320,000 DWT.
ULCC ultra-large crude oil carriers are similar to the VLCC, range at 320-550,000 DWT, became a problem with a potential risk to cargo and the environment.
Details on Passenger Vessels/Cruise Ships
Steam turbines are inefficient when compared with motors. Turbine power is quiet and generally vibration free. One of the modifications was that the steam turbine was replaced by diesel alternators with the alternator sets mounted on resilient motors. The drive system was an electric motor driving the propeller shaft, and as a result, efficiencies came with a quieter, more efficient outcome.
The new build passenger vessels have continued with this form and use diesel alternators to power azipod systems. Azipod utilises a power generation system, plus it uses the electrically driven direct connection to operate the pods attached to the outer hull. These can be driving azimuth propeller pods located at the stern. They can also power using two smaller pods mounted at the bow.
The use of azipod can be adopted for use with ice-strength hulls and using the propellers to access through ice.
Details on roll-on roll-off vessels
-Twin screw
- Have sufficient power to travel at an average service speed of 20 knots.
- Diesel-powered vessels are generally the preferred option for versatile use.
- Most are fitted with bow and sometimes stern thrusters for reasonably easy turning and berthing.
- Stabilisers are generally required, particularly where passenger travel is provided.
- The use of LNG/LPG as the main fuel can assist with the operational cost of operation and it is noted that some new builds are being fitted with either duel fuel or LNG as the operational fuel.
- The fact that sulphur is not a problem with LNG reduces the cost of operation. If compliant fuel is used, the benefit in operation is well worth the effort.
Details on Offshore Vessels and Tugs
- Usually larger than a tug, does use similar operational equipment.
- Tugs can be as simple as a standard operation using propellers and shafting, sometimes fitted with a nozzle and used for a tug and barge operation.
More complex tugs can be the ASD (asmuithing stern drive) Type fitted with Kort nozzles and a still more complex unit if a tractor tug that could be used for indirect towage. Where the tug is used to assist the steering of a vessel operating in enclosed water.
Where Kort nozzles are used, the thrust is contained and directed and provides a very positive outcome.
Details on Special Purpose Vessels
They can be vessels used to construct a range of maritime structures, such as the wind turbine construction vessels that were used particularly around Europe to build the structures required. There are any amount of vessels used to construct production platforms for the oil industry.
The more common, are the vessels specially designed and built to construct and deepen channels and other structures, such as the recent widening of the Panama Canal.
The different designs of dredge and hopper to move and relocate huge amounts of spoil and stone. These vessels are often complex pieces of machinery and the vessel shown here is used in the construction of port facilities around the world.
The suction pipe is 1300 mm in diameter and can operate to a depth of 150 metres. The vessel is fitted with two electrically driven suction pumps of 6500 kW. The vessel has a storage space for 46,000 cubic metres of sand and silt and can shift up to 75,000 tonnes in a single day. Just one of the special-purpose vessels.
