Bulwarks can be defined as the extension of side shell plating above the level of the weather deck which serves as a solid, providing safety to passengers and crew on board to prevent them from falling off the vessel.
Bulwarks in ships don’t play a major role in providing structural integrity and hence the plating used for them is considerably less thick than the other structural plates.
Let us get into more details to find out more.
Bulwark design and construction
Bulwarks are designed as per minimum requirements from those mentioned as from classification societies in terms of their minimum height and plate thickness requirements.
In open areas the height is specified to be a minimum of 1 meter as per IMO rules only in exceptions can it be less than 1m if it affects the ship’s operability. The bulwarks are normally supported by stanchions.
Special openings called freeing ports can be found on bulwarks on the level with the weather deck through which green water or water accumulated due to weather conditions can freely run off the vessel’s deck to the outside.
Structurally the bulwarks are normally supported by rail sections and stays that connect to the main deck. The spacing of these stays is normally calculated by an empirical formula given by the class society rules which are related to the ship length which is 0.93*L R not more than 1.2m apart.
In places of openings such as freeing ports, the edges are stiffened, and also in areas where mooring lines pass through the thickness is normally doubled or the necessary amount of stiffening is provided.
Also, it should be noted that the bulwarks should not be cut for any purposes at the breaks of superstructure such that there won’t is any structural weak points to ensure efficient load transfer.
Bulwark’s Advantages And Disadvantages
Bulwarks can serve multiple advantages along with some disadvantages, the main advantages of bulwarks are,
- Provides a safe path through which passengers and crew can walk outside on the deck without the risk of falling off.
- Fishermen use the support of a bulwark for leaning onto while casting which gives them a firm ground to reel in the fishes.
- Bulwarks can have cutouts through which fender lines can be drawn and also fittings as cleats can also be housed on bulwarks.
- Bulwarks also have openings called scrappers or freeing ports through which water can freely escape from the main deck to the outside.
The disadvantages are mainly the below,
- May interfere with the operation of the vessel in certain areas for workboats and similar vessels.
- Cannot be highly loaded in terms of pin or point loads as the plating used is comparatively much thinner when compared to other sections and won’t be able to handle higher external forces.
Bulwarks can be found throughout the vessel’s exterior boundary which plays a major role in terms of safety for passengers and crew on board and is mandatory for all vessels both commercial and non-commercial.