1. Lesson Five
Bulkheads and Pillars

3. 主讲内容 BHD BHD spacing BHD construction functions types cargo ships
general
Passenger ships
stiffening

4. The walls of the ship serve a variety of functions
The walls of the ship serve a variety of functions. The main reason for the formation of bulkheads is to create compartments which can be used for storing cargos or creating accomodation spaces. It's believed that Chinese were the first people who started using bulkheads in their ships. Prior to that the whole hull of the ship used to be an open space.
Not only that, bulkheads provide structural stability and rigidity to the ships. They also minimizes the violent sheer forces acting on the ship, that are generated due to waves. Moreover bulkheads are also useful from safety point of view. They prevent water from entering different parts of the ship in case there is flooding.

5. Language points main bulkhead minor bulkhead
heavy bulkhead light bulkhead
watertight bulkhead non-watertight bulkhead
transverse bulkhead longitudinal bulkhead
collision bulkhead aft peak bulkhead
corrugated bulkhead swedged bulkhead

6. Main bulkhead & minor bulkhead
Main bulkheads are structurally important and must be watertight to contain flooding in a ship accident.
Minor bulkheads are non watertight and not structurally important and designed to subdividing compartments into small units of accommodation or stores

7. Heavy bulkhead & light bulkhead
Heavy bulkheads are made of thicker steel plates with larger dimensions and work as major strength members
Light bulkheads are made of light steel plates with smaller scantlings and work as minor strength members

8. Watertight /non-watertight bulkhead
Watertight bulkheads are used nowadays in all most all types of ships. They provide maximum safety in times of flooding or damage of hull. They divide the ship into watertight compartments which prevents seeping of water to other parts of the ship incase the hull is broken. The number of compartments that a particular ship has depends on the type and requirement of the vessel.
They also facilitate storage of different types of cargo at the same time. Incase there is a fire, they prevent the source of fire or the flame to pass over to other compartment. They increase the overall strength of the ship by increasing the transverse strength. The number of bulkheads depends on the length of the ship and arrangement of machinery. It is imperative for all the ships to have a collision bulkhead

9. Transverse& longitudinal bulkhead
The former extends from side to side
The latter extends from bow to stern

10. Collision bulkhead& aft peak bulkhead
The former fitted forward to protect the ship and its crew in case of collision.
The latter fitted at the end of engine room to protect the heart of the ship without which the ship will lose power

11. Swedged&corrugated bulkhead
Both are characterized by not fitting stiffeners.
The use of corrugations or swedges in a plate instead of welded stiffeners produces as strong a structure with a reduction in weight. The troughs are vertical on transverse bulkheads but on longitudinal bulkheads they must be horizontal in order to add to the longitudinal strength of the ship. The corrugations or swedges are made in the plating strakes prior to fabrication of the complete bulkhead.

12. vertical stiffener
transverse bulkhead plating
vertical girder
side stringer
bottom plating
longitudinal bulkhead
side framing
horizontal girder
horizontal bracket
bottom center girder

13. horizontal girder
corrugated bulkhead plating
section form of bulkhead plating

14. spacing
Any bulkhead which separates any space allocated for the accommodation of passengers, other than as exercise space, from any space used as-
(a) a permanent coal bunker; (b) an oil fuel bunker; (c) a machinery space; (d) a lamp room or paint room; (e) a dry provision store room or any store room other than a linen locker, medicine locker or lifejacket locker; (f) a chain locker; or (g) a cofferdam,
shall be constructed of steel and shall be gastight and, where required, suitably insulated and, where necessary, watertight, to protect the passenger space.

16. Plain bulkhead
The plating strakes are horizontal and the stiffening is
vertical. Since water pressure in a tank increases with depth and the watertight bulkhead must withstand such loading, the bulkhead must have increasingly greater strength towards the base.This is achieved by increasing the thickness of the horizontal strakes of plating towards the bottom. The collision bulkhead must have plating some 12% thicker than other watertight bulkheads. Also, plating in the aft peak bulkhead around the stemtube must be doubled or increased in thickness to reduce vibration.

19. Assignment Memorize the language points
Review the drawings with structure terms