Page 290 - Ship Construction.DJ Eyres 6Ed

Ch24-H8070.fm Page 279 Wednesday, October 18, 2006 7:00 AM
Lifting Arrangements 279

Heavy derrick Mast

Insert plate
Derrick stool Winch deck
--- ใช้เพื่อการศึกษาเท่านั้น---
Centre line Centre line girder
bulkhead Transverse
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
bulkhead Upper deck
Insert plate
Stiffener
centre line Upper tween deck
plate web

Lower tween deck
ึ
Bracket
Watertight bulkhead

Heavy bulkhead
stiffener on
centre line

Bracket Stiffener on
centre girder
Tank top

FIGURE 24.1 Stiffening in way of mast and heavy derrick

controlling the winches for the cargo runner. Variations on this rig are often
adopted; for example the ‘butterfly’ rig (Figure 24.2(c)) which is used where
cargo is discharged from a hold to both sides of the ship.
Where a weight exceeding the safe working load of the derricks is to be
lifted the ‘yo-yo’ rig is sometimes adopted (Figure 24.2(d)). The heads of
the derricks are brought together, and a travelling block may be arranged on
the cargo runner or a wire connecting the two cargo purchases as illustrated.