8.(a) Describe the basic construction and operation of a Vertical Ship Lift.(6)
(b) List TWO advantages and TWO disadvantages of a Vertical Ship Lift.(4)
(a) Basic construction and operation of a Vertical Ship Lift (6 marks)
- Construction
- A platform (deck) large enough to support the vessel’s full length.
- The platform is supported by multiple wire ropes or chains connected to winches or hydraulic hoists.
- Guides and support towers/caissons at the sides keep the platform stable during movement.
- The platform rests on docking blocks positioned according to the vessel’s docking plan.
- Operation
- The vessel enters the lift and is positioned over the docking blocks.
- The lift is then raised vertically by synchronised winches or hydraulic rams, lifting the vessel clear of the water.
- Once raised, the platform can:
- remain in position for repair, or
- transfer the vessel laterally onto a shore-based transfer system (rails/trolleys) for positioning in a repair bay.
(b) Advantages and disadvantages of a Vertical Ship Lift (4 marks)
Advantages (2):
- Can handle multiple vessels quickly by transferring them ashore after lifting.
- Requires less waterfront space compared to traditional graving docks or floating docks.
Disadvantages (2):
- High initial capital cost for construction and installation.
- Limited by platform size and lifting capacity, so unsuitable for very large vessels.