Moon pool hatch covers MARINE - TTS Group ASA

MOON POOL HATCH COVERS
The drawings show some of the
various moon pool cover designs
installed onboard different
offshore vessels.
Bottom moon pool covers
A commonly used type is the
side hinged two-section cover
shown in Figure 2. In open
position the two sections
ensure a flat moon pool surface
free from obstructions. As
an alternative, a side hinged
foldable cover can be installed
stowing in one of the sides.
Figure 1 shows a top moon
pool cover, and the principle
is identical for a bottom cover.
Both types are hydraulically
operated and cleated and the
movement controlled by guides
fitted at each side of the cover.
Figure 4 shows a lifting and
sliding cover, operated by
hydraulic cylinders and by rack
and pinion.
Fig. 2
Cleating
Hydraulic
cylinder
Cover in open and
secured position
Fig. 3
Fig. 4
Top moon pool covers
Top covers are normally fitted
whether or not bottom covers are
installed. An inexpensive solution
is to install a lift-away cover
operated by a crane, secured by
manual cleats or by a hydraulic
system fitted into the coaming.
Where the moon pool is placed
in a hangar area several other
alternatives may be considered.
Side hinged covers in one or two
sections can be hydraulically
operated and cleated (Figure 1).
Sliding covers are usually installed
where there is limited height. With
this solution (Figure 3), cargo
does not need to be removed
when operating the hatch cover.
A much used solution is similar
to that shown in Figure 2 as a
bottom hatch cover, but this
time located at the top of the
moon pool. Two side hinged
panels open downward into a
recess in the moon pool trunk,
thus avoiding snagging any
equipment in the hangar.
Fig. 1
Cleating Cover in closed position
Parked
Closed
Open
Cover in open and
secured position
Hydraulic cylinder
Deck
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