Discuss different conventional hatch including the structural components, testing methods and watertight and weather tight of the hatch cover. A cargo hatch or deck hatch or hatchway is type of door used on ships and boats to cover the opening to the cargo hold or other lower part of the ship. To make the cargo hold waterproof, most cargo holds have cargo hatch. Hatch covers of ships are designed to be efficient and cost-effective, as an initial investment and during service, and at the same time should suit the demands of the various types of cargo vessels. With the many changing trends of cargo transportation, it would be expected that the design and structure of cargo holds would change to meet the needs of modern shipping. This is clearly evident with container tonnage and the vehicle decks of the Roll-on, Roll-off (Ro-Ro) vessels. However, the changes in the carriage of general cargoes have been comparatively small. This is possible because most merchandise will suit the more popular container or similar unit load movement. Hold structures have tended to go towards square corners to reduce broken stowage (BS), and suit palletization, pre-slung loads and the use of the fork lift truck inside the holds. Stowage by such vehicles are aided by flush decks in way of the turn of the bilge, as opposed to the angle turn in the sides of the holds of older tonnage. Some specialist cargoes, like steel coils , still suit conventional holds and clearly would not be compatible inside containers, because of the shape and weight of each item. As with large case goods or castings, which tend to transport better by means of conventional stowage in the more conventional type vessel. Such merchandise is clearly edging towards heavy-lift type loads and these heavier loads are covered in detail here, alongside the designated heavy-lift ship and project cargoes. The objective of this chapter is to provide an overall picture of an industry sector which is an essential part of cargo handling and general shipping practice. It does not have such a high profile...

1. GROUP 2
Cdt. Carag
Cdt. Dizon
Cdt. Dumag
Cdt. Flores
Cdt. Francisco

2. Hatchwork

3. LO 1.2 Discuss different conventional
hatch including the structural
components, testing methods and
watertight and weather tight of the hatch
cover

4. What is hatch
•A cargo hatch or deck hatch or hatchway is
type of door used on ships and boats to
cover the opening to the cargo hold or other
lower part of the ship. To make the cargo
hold waterproof, most cargo holds have
cargo hatch.

5. Overview
•Hatch covers of ships are designed to be
efficient and cost-effective, as an initial
investment and during service, and at the
same time should suit the demands of the
various types of cargo vessels.

6. •The major objective of hatch covers and
coamings on ships is to prevent the ingress
of water into the cargo hold and protect the
goods from being damped and damaged.

7. •Hatch covers also act as a barrier to the
ship’s internal structure by enduring the
green water loads in extreme weather, which
can damage the internal structure of the ship
due to corrosion.

8. Types Of Hatch
Covers

9. Lifting type
•Lifting type or lift away type hatch covers are
generally used on container ships, whereas
rolling type is used on bulk carriers (to be
specific side-rolling). Rolling type can be
divided into end rolling, side rolling, and
piggyback & telescopic.
•Lift away type hatch covers can be classified
into two types.

10. •Single panel •Single panel

11. Folding type
•Folding type hatch covers are basically used
on general cargo ships. However, these may
vary depending on the stowage space and the
type of cargo that is carried. Folding type hatch
covers consists of two flat type topped panels
which are operated via hydraulic arms. These
may be fitted on both weather deck as well as
tween deck. A major advantage in the design
of folding type hatch covers is its large size
which means less number of panels.

13. Rolling type
•Rolling type hatch covers consists of two
covers at the end of the hatchway. Wheels
are fitted which help in the sliding of the
panel either athwartship in case of side
rolling or longitudinally in case of end rolling.

14. •These type of hatch covers are usually fitted
on large ships. Hydraulic rams are required
to raise them to rolling position as they are
extremely heavy and have very large
dimensions.

16. Stacking cover type
•These type of facility are used on ships
having relatively smaller hatch cover. It
consists of a hydraulically powered lifting
crane facility whose purpose is to lift the
covers longitudinally and stack it together at
one end or over any empty stowage tank. It
is relatively cheap and is used mostly in
barges.

18. Structural components of hatch cover
•Designing a hatch cover does not mean just
designing the cover and its coaming, there
are various key components which ensure
that the hatch cover stays intact and
effective for a very long period. The key
parts are as follows –

19. •Bearing pads
•Securing devices: cleats & wedges
•Pontoons and panels
•Operating mechanism
•Stoppers
•Drains & non-return valves
•Compression bars

20. •It should be ensured that the maintenance of
the above-mentioned components is done
on a regular basis in order to ensure the
safety of the cargo and the effectiveness of
the hatch cover & coamings.

21. General considerations while
designing the various components of
the hatch cover are as follows:
•Deck Opening: The strength of the hull is
dependent on the size of the deck opening.
High tensile steel must be used to provide
adequate longitudinal strength even in ships
where the hatch width is more than 70% of
the width. Detailed structural design and
strength analysis should be carried out on
ships with large hatchways.

22. Stress concentration points are usually
located at the corners of the openings which
can be eliminated by providing thick elliptical
or parabolic plates.
•Coaming Height: Height is measured above
the upper surface of the deck. They are
closed by steel covers fitted with direct
securing arrangements. However, the
coaming can also be omitted as long as the
safety of the ship is not at risk.

23. Majority of ships have coaming height of
about 1-1.8 m in order to accommodate more
cargo, especially, in bulk carriers. Coamings
can also be designed by sloping them
inwards, creating a larger opening at the deck
level.
•Hatch Corner Construction: The designer
should avoid sudden discontinuity of
longitudinal strength at the ends of side
coaming.

24. The girders are extended to a suitable end
beyond the hatch end for structural continuity.
Usually, taper brackets are used to extend the
hatch coaming in order to reduce stress
concentration. As mentioned earlier elliptical
or parabolic plates at the corners also help in
reducing stress concentration which would
otherwise lead to fatigue followed by fracture.

25. •Drainage: Proper drainage facility should be
provided in order to prevent the damage of
sensitive cargo. This can be done by
providing a channel around the peripheral
seal of the hatch cover which ensures that
the water is discharged onto the weather
deck through a hole in the coaming.

26. Testing of Hatch
Covers

27. Hose water Test
•In this test a water spray from a nozzle of
12mm diameter is sprayed over the joint of
hold and cover from a distance of 1m to 1.5
m with a pressure of 0.5 m/ second water
jet.
•The limitation or drawbacks of this test is
that it requires two persons and hatch cover
to be tested must be empty.

28. •The leakage if very minimal cannot be
identified by naked eye and cannot be
performed in sub zero or cold weather.

29. Ultrasonic Test
•The Ultrasonic testing is a more accurate
method of testing water tightness of hold
and its cover. In this system an ultrasonic
generator is kept inside a closed and intact
cargo hold.
•A sensor of that unit is passed all over the
compression joint and any low pressure area
or point detected by the instrument can be a
leakage point.

30. •Few drawbacks of this instrument is it is not
normally kept onboard and qualified person
is required to perform this test.

32. Chalk test
•This is the oldest or most traditional method
for testing hold cover compression, but it
cannot test the water tight integrity of the
hold.
•A layer of chalk powder is applied all over
the steel back of the hatch and then the
hatch cover is closed and tightened to its
normal values.

33. •The impression of chalk on the rubber
packing is then studied to check lack of
compression point shown by gap in the
chalk marks.

35. Video

36. Content
(Arial 40-44)

37. 10 Questions
Arial