Answer Construction Question 4
Question
4: Draw and Describe the construction of a fore peak tank. Explain How
are the effects of panting and pounding taken care with help of neat
sketches?
Answer: Tanks
located at the extreme end of the ship are termed as peak tanks. Tanks
at the fore end of the ship is termed as Fore Peak tank, tank at the aft
end of the ship is termed as Aft Peak Tank. Fore peak tank is the
volume enclosed between the Collision bulkhead, ship's hull plating and
the fore peak tank top.
The following structures are found in the fore peak tank:
1. Stem plate or stem bar or a combination of both in the forward most structure, which forms the profile of the bow. The stern plate is normally made of steel plate and is stiffened by a center line girder or stiffener. The stem runs from the highest point at the forecastle to the keel of the ship.
2. Breast hooks are fitted at intervals to stiffen the stem plate and to connect the stem plate to the panting stringers or side stringers.
3. Deck head is the uppermost deck of the fore peak tank which Is watertight. Entry to the fore peak tank is through man holes which are kept watertight by covers when ship is under way.
4. Panting stringers or side stringers are fitted at regular intervals on the ship side to reduce panting, the inward and outward deformation of side plating caused by the changes in water pressure.
5. Panting beams are normally spaced at every other frame space to absorb the transverse fluctuating forces induced during slamming and pounding of the ship. Channel bars are normally used as panting beams. Panting beams are also sometimes supported by pillars.
6. Perforated bulkhead (also known as swash bulkhead or wash bulkhead) refers to the centerline bulkhead which is not watertight. Its main function is to reduce free surface effect or heeling moments of water in tanks, which are not fully filled.
7. Perforated flat (also called perforated deck) is a horizontal deck which is non watertight. It acts as a kind of a full panting stringer to absorb the transverse forces. The deck is supported by panting beams and longitudinal girders like a usual deck The perforations on the deck are to facilitate the flow of liquid in the fore peak tank and also for man entry.
8. Solid floors are fitted at every frame spacing to reinforce the ship's bottom. A centerline girder is normally fitted to provide for rigidity of the structure with the transverse floors.
9. Collision bulkhead is mandatory and to be fitted at aft of the fore peak tank at a distance of 5 to 7.5% length of the ship from forward perpendicular.
This tank is located in the high stress
regions of the ship, hence it is fitted with special strengthening
arrangements termed as panting arrangements. Access to this tank Is
provided through manhole located on the tank top.
It is a watertight tank normally used for ballast purposes for proper trim especially on the ballast voyage.
A watertight collision bulkhead is fitted in the fore peak tank to minimize the damage to the cargo located aft of the collision bulkhead in the event of a collision. The chain locker for storing the anchor chain is normally located inside the fore peak tank.
It is a watertight tank normally used for ballast purposes for proper trim especially on the ballast voyage.
A watertight collision bulkhead is fitted in the fore peak tank to minimize the damage to the cargo located aft of the collision bulkhead in the event of a collision. The chain locker for storing the anchor chain is normally located inside the fore peak tank.
1. Stem plate or stem bar or a combination of both in the forward most structure, which forms the profile of the bow. The stern plate is normally made of steel plate and is stiffened by a center line girder or stiffener. The stem runs from the highest point at the forecastle to the keel of the ship.
2. Breast hooks are fitted at intervals to stiffen the stem plate and to connect the stem plate to the panting stringers or side stringers.
3. Deck head is the uppermost deck of the fore peak tank which Is watertight. Entry to the fore peak tank is through man holes which are kept watertight by covers when ship is under way.
4. Panting stringers or side stringers are fitted at regular intervals on the ship side to reduce panting, the inward and outward deformation of side plating caused by the changes in water pressure.
5. Panting beams are normally spaced at every other frame space to absorb the transverse fluctuating forces induced during slamming and pounding of the ship. Channel bars are normally used as panting beams. Panting beams are also sometimes supported by pillars.
6. Perforated bulkhead (also known as swash bulkhead or wash bulkhead) refers to the centerline bulkhead which is not watertight. Its main function is to reduce free surface effect or heeling moments of water in tanks, which are not fully filled.
7. Perforated flat (also called perforated deck) is a horizontal deck which is non watertight. It acts as a kind of a full panting stringer to absorb the transverse forces. The deck is supported by panting beams and longitudinal girders like a usual deck The perforations on the deck are to facilitate the flow of liquid in the fore peak tank and also for man entry.
8. Solid floors are fitted at every frame spacing to reinforce the ship's bottom. A centerline girder is normally fitted to provide for rigidity of the structure with the transverse floors.
9. Collision bulkhead is mandatory and to be fitted at aft of the fore peak tank at a distance of 5 to 7.5% length of the ship from forward perpendicular.
Arrangements to resist panting
The
structure of the ship is strengthened to resist the effects of panting
from 15% of the ship's length from forward to the stem and aft of the
after peak bulkhead.
In the fore peak, side stringers are fitted to the shell at intervals of 2m below the lowest deck. No edge stiffening is required as long as the stringer is connected to the shell, a welded connection being used in modern ships.
The side stringers meet at the fore end, while In many ships a horizontal stringer is fitted to the collision bulkhead in line with each shell stringer. This forms a ring round the tank and supports the bulkhead stiffeners.
The structure Is strengthened to resist the effects of pounding from the collision bulkhead to 25% of the ship's length from forward.
The flat bottom shell plating adjacent to the keel on each side of the ship is increased in thickness by between 15% and 30% depending upon the length of the ship, larger ships having smaller Increases.
In addition to increasing the plating, the unsupported panels of plating are reduced in size. In transversely framed ships the frame spacing in this region Is 700 mm compared with 750 mm to 900 mm amidships.
Longitudinal girders are fitted 2.2 m apart, extending vertically from the shell to the tank top, while intermediate half-height girders are fitted to the shell, reducing the unsupported width to 1.1 m.
Solid floors are fitted at every frame space and are attached to the bottom shell by continuous welding.
In the fore peak, side stringers are fitted to the shell at intervals of 2m below the lowest deck. No edge stiffening is required as long as the stringer is connected to the shell, a welded connection being used in modern ships.
The side stringers meet at the fore end, while In many ships a horizontal stringer is fitted to the collision bulkhead in line with each shell stringer. This forms a ring round the tank and supports the bulkhead stiffeners.
The structure Is strengthened to resist the effects of pounding from the collision bulkhead to 25% of the ship's length from forward.
The flat bottom shell plating adjacent to the keel on each side of the ship is increased in thickness by between 15% and 30% depending upon the length of the ship, larger ships having smaller Increases.
In addition to increasing the plating, the unsupported panels of plating are reduced in size. In transversely framed ships the frame spacing in this region Is 700 mm compared with 750 mm to 900 mm amidships.
Longitudinal girders are fitted 2.2 m apart, extending vertically from the shell to the tank top, while intermediate half-height girders are fitted to the shell, reducing the unsupported width to 1.1 m.
Solid floors are fitted at every frame space and are attached to the bottom shell by continuous welding.
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