Single pull macgregor type hatch cover.pdf - Cochin University of ...

It is also necessary to provide drainage for the vehicle deck in Ro-Ro vessels.
Any scupper which drains a space within an intact superstructure on the free board
deck (usually the main vehicle deck) is led overboard through a pipe fitted with a
screw-down non return valve having open/shut indicators and capable of being
operated from accessible positions above the freeboard deck. Alternatively the
scupper may be led down to the bilges or to a drain tank. In an enclosed tween deck
space with a continues centre-line casing, additional scuppers must be installed
adjacent to the casing on the main vehicle deck. Where the inboard end of a deck
scupper would be below the load waterline at an angle of heel less than 15 degree, it
should be led to a separate drain tank, which may be pumped overboard.
3.3 SPECIFIC DESIGN REQUIREMENTS FOR HATCH COVERS
3.3.1 Hatch Covers
The hatch cover structure consists in essence of steel beams or grinders spanning the
shorter hatchway dimension, plated over on top completed by steel side and end
plates. The top plate provides the top flange of the beams and grinders. For the
simpler types of hatch cover panel, e.g. pontoon or single pull, the design and analysis
assume a uniformly loaded simply supported beam as shown in the fig 3.2.
Figure 3.2 Beam is treated as a uniformly loaded simply supported structure
3.3.1.1 Structural regulations
Source: Cargo Access Equipment for Merchant Ships.
The construction of exposed hatch covers is governed by regulations 14 to 16 of the
1966 Load line convention (1966 LLC). Regulation stipulates that exposed coamings
and hatchway covers above the superstructure deck shall comply with the
requirements of the appropriate national administration, which means in effect, that
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