There are no specific Special Category codes which include jetties, pontoons, berthing and mooring dolphins and shore-arms etc. These maritime and inland waterway structures usually form part of another hereditament, such as oil refineries, liquid bulk storage, gas storage, ship building/repair yards and chemical works.
Maritime and inland waterway structures forming part of local list hereditaments will generally be valued by reference to the contractors basis, using estimated replacement build costs.
Estimated build costs for the structures listed below are contained within the Valuation Office Rating Cost Guide (RCG) and this guidance should be read as an aid to correctly applying these costs.
A structure projecting from the shore out into the water to allow ships or boats to come alongside for mooring or loading/unloading. Jetties are rateable as part of the land.
These are jetty structures that provide walkways or roadways and sometimes pipe-racks from shore to boat or ship berths located in deeper water. The typical form of construction is an open structure comprising a suspended reinforced concrete deck supported by steel tubular piles, however structures in shallower water may use a closed structure using granular infill between a pair of walls with ties between.
Berthing heads are jetty structures that vessels berth against (berth means the ship is tied up to the jetty or dock) and may incorporate strongpoints with berthing and mooring structures. They are typically located in deeper water.
Berthing dolphins are freestanding structures, (usually secured by piles to the sea or riverbed), that are used to bring a vessel to a halt by absorbing the energy from its approach speed, through fender units that are mounted to the face of the structure.
A mooring dolphin is a structure designed to resist mooring line (rope, cable or chain) tensions, rather than berthing impact forces. Generally, the loading applied to mooring dolphins is less than berthing dolphins, with mooring loads resisted by lines fixed to multiple structures.
A catwalk or walkway is a pedestrian bridge providing operational or maintenance access to offshore dolphins. Load bearing capacity is typically low, as the walkway capacity is limited by the width of the walkway. The structures are typically fabricated offsite, using steel or aluminium sections and are delivered as completed items.
Figure 1 below illustrates a typical layout for some of the above items.
Seaward end where ships will berth
Pontoons are floating platforms capable of accommodating the berthing of offshore vessels. They are linked to the adjacent land or wharf by a bridge. They are more heavily engineered than the pontoons typically found in marina environments and are normally a concrete structure. Pontoons are attached to dolphins (piles), anchors, and other forms of attachment, which permit the pontoon to move vertically to accommodate changes in water level, whether within a dock or due to tidal changes in a harbour. Dolphins in marina environments will typically be smaller than those referenced elsewhere in this document and are used simply to anchor a pontoon in place.
A vertical pile driven into the sea, river or dock bed which is used as a fixing point for a pontoon.
Quays and wharfs (usually where the sea or river side has been artificially built up to provide a level access for boats or ships to come alongside), provide the vertical interface for ships to berth, moor, load and unload goods, personnel and equipment.
A drydock comprises an enclosed dock with the ability to drain it of water to enable vessel construction, repair, and maintenance in a dry environment.
Locks allow raising or lowering of ships or boats between different water levels. They consist of chambers with gates that can be filled or emptied to match the differing water levels.
Dock gates and Caisson Gates are watertight barriers located at the entrance or exit of a dock or basin. They control water flow, manage water levels, provide access for vessels, and protect against flooding. Dock Gates are normally steel manufactured gates that can open and close, Caissons are large concrete structures that are ballasted and floated in and out of position at high tide.
A slipway is an inclined surface usually made of concrete, generally used for launching, hauling, maintenance and retrieving of vessels, and also the landing of goods and personnel. They can vary significantly in size depending on use.
Dredging is the process of excavating or removing sediment, debris, or other material from the bottom of bodies of water, such as rivers, lakes, harbours, or oceans. It is primarily done to deepen waterways, maintain navigation channels, control erosion, restore water bodies, or extract valuable minerals and resources.
A linkspan is a type of movable bridge or ramp used to connect a fixed structure, such as a dock or quay, to a ship or ferry. It provides a secure and stable platform for passengers, vehicles, and cargo to move between the shore and the vessel.
A passenger boarding bridge is a mechanical connection bridge between the shore and the boat or ferry to allow passengers to disembark and embark from the vessel to the shore. Bridges typically found in marina environments will normally be of light construction.
For further advice, please contact a member of Class Co-ordination Team for Specialist Industrial Contractors property.
