How many types of lifting gear onboard dry cargo ships?
There are four main types of lifting gear on Dry Cargo ships; under each type there are many designs with a variety of lifting capacity, which varies between 3 tons up to 400 ton on unspecialized ships, and can exceed that on heavy lift ships.
There are four main types of lifting gear on Dry Cargo ships:
1- Union Purchase
2- Single Swinging Derrick
3- Cranes, Deck cranes both level-luffing
4- Shipboard Gantry System
Parts of Derrick
Topping Lift
Topping Lift blocks.& Link band
Runner
Runner blocks (Head block Heel block)
GoosenecK
Guys
1- Union Purchase
The Union Purchase rig consist of two derricks One derrick, called the ‘ship derrick And the other, called the ‘off-shore derrick’
The Union Purchase rig consist of two derricks, One derrick, called the ‘ship derrick’ is positioned over the hatch-opening (hatchway) in order to allow a direct vertical lead to the cargo within the hold and the other, called the ‘off-shore derrick’ is positioned clear of the rail to allow of discharge to the berth or lighter (barge).
2-Single Swinging Derrick
Swinging derrick rig consist of one derrick placed in the centre of the vessel, it was named swinging because the derrick swing back and forth between the hatchway and the dockside (or lighter) during Loading/Discharging.
3- Cranes, Deck cranes both level-luffing
Electro-hydraulic single deck cranes have hoisting capacities of 3, 5, 8, 10, 12, 15, 20, 25, 40 tons.
4- Shipboard Gantry System
Other crane design is the gantry crane, similar to shore based container gantry crane.
This design is not wide spread onboard vessels as the traditional one.
The ship is equipped with two rails near the bulwark running the full length of the main deck from under the forecastle up to the superstructure, this enable to position the gantry crane exactly on top of the cargo.
This design achieved very good loading/discharging rate with light homogeneous cargo, capacity of these cranes varies but the most common is between 20 to 30 Ton.