2) Maximum trim of 1.7 degrees.
3) Minimum freeboard of 2.5 feet at the lowest point, at combined
list and trim angle.
4) Minimum transverse metacentric height (GM) of 35 feet.
5) Residual dynamic stability of not less than 15 foot-degrees
between the curve of static stability and the heeling arm curve. This stability
is taken between the healing arm equilibrium point (list angle) of maximum
ordinate differences between the two curves, but not exceeding 40 degrees.
(However, protection against downflooding is required to 40 degrees of heel.)
6) Sufficient dynamic stability to prevent capsizing in case of
sudden loss of the hook load of any hoist, including test loads of 130 percent of
rated capacity. Specifically, the righting arm area (foot-degrees) on the crane
counterweight side must be adequate to absorb the energy imparted to the entire
crane by the sudden loss of the rated hook load.
For overload tests with 130 percent rated capacity on any load hook, with
no deck load, and with the most adverse upperworks rotate position and boom angle,
the barge must remain within these limits:
7) Minimum freeboard of 1.0 foot at the lowest point, at combined
list and trim angle.
8) Upper bilge tangent, adjacent to any flat bottom area,
completely under water.
Towing Configuration. For towing, the boom is secured in the boom
rest and there is no deck load. The water ballast compartments are used to obtain
the required trim. For this towing configuration, three cases are considered:
1) Minimum freeboard of 5.0 feet.
2) For towing in protected waters, minimum trim of 2.0 inches down
by the stern.
3) For towing on the open seas, minimum trim of 1.0 foot down by
Container Cranes. Five cases are considered for container crane
stability in the operating (boom horizontal) and stowed (boom raised and secured)
Operating Configuration. Container cranes in their operating
configuration must be analyzed with the trolley at its maximum outreach and
maximum backreach. The resultant of all forces is translated to the plane of the
tipping axis either on the rails or through the main gudgeon pins. When the
tipping axis is the rail, the maximum wheel flange clearance on the rail head must
be included in the analysis. (Normally container cranes operate on straight track
and have no travel truck float.) The resultant of all forces must be within 95
percent of the distance from the crane's geometric center to either rail or the
main gudgeon axis, as applicable. The following three cases are considered: