harbour and dock

1. HARBOUR AND DOCK
ENGINEERING

3. Types of repair docks
1. Graving or dry dock
2. Floating dry dock
3. Marine railway dock
4. Lift dry dock

4.  Stands like a grave
 It is long excavated chamber, having side walls, end
wall and a floor. The open end of the chamber is
provided with a gate and acts as the entrance to the
dock.
 side walls - 2m steps – galleries - culverts

5. Graving dock
Entrance lock
Keel block
Bilge blocks

6. SHIP IN DRY DOCK
Keel block

7. LOCK GATE

8. CROSS SECTION OF A GRAVING DOCK
Keel block- Wooden 120 to 140cm high and placed at 120cm c/c

9. In form of cranes having capacities 2 - 50 tonnes.
Ensures working of pneumatic tools for cutting, drilling..
It is to fill or flood the dock chamber through culverts provided
inside walls.
For cleaning of ship surface.

11. Power supply is required for the running of welding sets,
Pumps and capstans.
These are well founded electrical motors known as capstans, on
both side of dry docks
bollards are very heavy iron ingots in dump-bell shapes 1/3rd of
which are founded on both sides at an interval of 3m-5m c/c.

15. Supporting the ship from sides
Supporting the ship from bottom
To make water level in the dock equal to water level in basin.
flooding is done by supplying water from an elevated tank via
pipe culverts.
To make the ship to sit exactly on blocks the water is to
pumped out of dry dock with high power pumps.

20.  Depends on
 Size of largest ship
 General - long dry dock
 300m in length
 Entrance width – 25m to 30m

21. 1. Weight of ship
2. Weight of water when flooded
3. Uplift pressure when empty
4. Earth and hydrostatic pressure behind side walls
5. Load imposed by shores on side walls
6. Load of cranes and moving appliances
7. Stress due to wind

22. Heavy uplift > weight of floor  Resultant is transferred to
shores by inverted arch action and resisted by weight of side
wall.
Heavy reinforced floor to carry load of ship
Load taken by foundation
The horizontal pressures behind the side wall are more resisted
by water pressure inside the dock.

23. a a
c1 c2c
d de e
b
sequence of
construction
manipulated
to ensure
stability of
structure
1. Site is
partly
excavated
and portion
marked ‘a’
of the side
wall is built.
2. The core
‘b’ is
excavated to
lay the floor
in short
lengths and
outer
sections
c1,c2 are
laid leaving
the core in
3. The
flooring in
the central
section is
placed after
excavating
the core c’.
4. The upper
portions of
the side wall
marked ‘d’
are
constructed.
5. The back
fill ‘e’ is
placed to
complete
the work.

24. The marine railway or slip dock or slip way is an inclined
railway extending from the shore well into the water as the off
there. This railway track is used to draw out a ship needing
repair out of the water.
Components of a marine dock:
The essential parts of a marine dock are as follows:
 Cradle
 Track
 Locking device

25. The essential parts of
marine railway dry dock
are:
1. Cradle:
It is constructed of
steel and is mounted on
a system of rollers which
move on iron tracks
carried by longitudinal
timbers, supported on
cross ties.

26. 2. Track:
It is being supported
on an unyielding and
firm foundation and
pile foundation.
3. Locking device:
It is for the safety pawls
under the cradle to keep
the cradle from slipping
down.

27. “A Slipway consist of inclined path of timber or
stone upon which a series of rails are fixed and run
up from a sufficient depth of water to the required
height above the high water level”.

29. SLIPWAY

30. 1.Flat footed rails: Standard sections are used.
2.Crane track foundations: It is partly in dry, partly b/w
tides and partly under water.
3.Cradle or Carriages:
a.Rigid : can handle up to vessels of 10000t and
require longer slips.
b.Semi rigid: Require shorter slips.
c.Collapsible: It is in the form of a series of bogies
connected by chain.

31. TRAVERSING SLIPWAYS:
“The slipways on which the ship after being
pulled up to the highest point can be
traversed sideways to other berths are known
as traversing slipways”.

32. “It is a substantially constructed platform capable
of being raised and lowered from water. It is done by
hydraulic power applied through cylinders”.

33. LIFT DRY DOCK

34. Hollow huge steel or RCC structure which can lift
a ship Under its own buoyancy.
when water is admitted it sinks down and lifts the ship when
unballasted
- Cheaper
-Can be constructed easily
-Mobile
-Repair of damaged ships
-No gate arrangements
-less service life (floating in salt water)
- Heavy maintenance cost
-Require great skill for operation

35. Rigid type
 Self docking type
 Offshore docking type

36. Floating dry dock

37. FLOATING DRY DOCK

38. The side walls are rigidly
fixed to the pontoon or
bottom section.
The floor portion is divided
in to no: of chambers so as
to assist in canting dock.

39. This type is constructed in 3 equal sections
having stepped to form landings.
It combines the advantages of strength of rigid type.

40. It has no side wall on the Water side and has an ‘L’
Shaped C/S.
The side wall is connected to shore by hinged parallel
booms capable of lifting or lowering the dock.

41. 1.WHEN LOADED WITH A SHIP:
The transverse strength of the structure should be
sufficient to enable the buoyancy of the side walls
and the side sections of the pontoon to carry the
concentrated load of the ship along the longitudinal
central axis of the floor.

42. 2.WHEN UNLOADED AND FLOATING:
The transverse section should be sufficient to
support the weight of the side walls and other
heavy machinery carried on side walls like
pumping units, cranes…

43. ADVANTAGES:
1. It is cheaper in initial and working costs.
2. It takes place 1/2 the time to construct floating dry
dock compared to graving dock of the same capacity.
3. Mobility and can be transferred from port to port.
4. It could be trimmed to take a damaged and lifting
ship.
5. It has no elaborate entrance or gate arrangements.

44. 1. The durability or service life is appreciably less.
2. Upkeep and maintenance are more.
3. The manoeuvring and towing of a floating dry dock
needs great skill and care.

45. THANK YOU