Page 229 - Ship Construction.DJ Eyres 6Ed

Ch19-H8070.fm Page 218 Wednesday, October 18, 2006 6:58 AM
218 Ship Construction

(a) ROLLING HATCH COVERS

--- ใช้เพื่อการศึกษาเท่านั้น---
Rubber gasket
Closed position
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
Section through
sides and ends
Hatch
Section through coaming
cross joint
between Dumb panel raised by high-lift cylinders
panels
Rubber
gasket

(c) WEATHER TIGHT GASKETS FOR Motorized panel rolled underneath
PATENT HATCH COVERS ึ

Both panels moved ‘piggy-back’ style
to fully open position (part or starboard)

(b) ‘PIGGY-BACK’ HATCH COVER

FIGURE 19.6 Hatch covers

the leading panels. Piggy back covers permit horizontal stowage of panels
avoiding fouling of lifting devices particularly in way of very large openings
such as on bulk carriers and container ships where the hatch need only be
partially open for working. The covers consist of a dumb panel which is
raised by high lift cylinders and a motorised panel which is rolled under-
neath the dumb panel. Both panels can then be moved ‘piggy back’ style to
the fully opened hatch position port or starboard or partially opened posi-
tion fore and aft. Pontoon covers are commonly used on container ships
being lifted by the ships or shore cranes with the container spreader. They
are closed weathertight in a similar manner to the other patent covers. Side
rolling are very common on large bulk carriers and can operate on similar