Page 42 - Practical Design Ships and Floating Structures

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7 IACS AND SOLAS REQUIREMENTS
7.1 Existing Bulk Curriers
To reduce the risk of failure in older ships, IACS introduced new Unified Requirements to reduce the
risk of progressive flooding in existing bulk carriers. To prevent progressive flooding due to sea water
in No. 1 Hold, the corrugated transverse bulkhead between the first two cargo holds, and the double
bottom in way of the first cargo hold had to comply with new strength requirements assuming that No.
1 cargo hold was flooded. A damage stability review had to be performed with No. 1 Hold flooded,
and more frequent and close-up surveys of critical areas such as side frames and side shell had to be
made.
7.2 New Single Side Skin Bulk Carriers

The IACS requirements for new single side skin bulk carriers address the folIowing structural areas:
increased requirements for the strength of side frames
longitudinal strength of vessel to withstand any hold being flooded
transverse watertight corrugated bulkhead strengths of a11 cargo holds to withstand hold flooding
double bottom strength to withstand hold flooding
increased strength requirements for hatch covers in forward holds
7.3 SOLAS Regulations

At a SOLAS Conference held at IMO, in November 1997, a new Chapter XII on bulk carriers was
added in SOLAS. The regulationdrequirements are essentially similar to the IACS requirements.
Compliance with IACS requirements is also required.

8 SAFETY IN CARGO HANDLING

Proper loading guidance is very important to safe cargo handling. The loading and discharging of
cargo can be a very significant factor affecting the structural safety of bulk carriers. This is especially
so in the case of dense cargoes such as iron ore.

How the ship is loaded and unloaded has not always been appreciated at the cargo terminals, where a
10-15 percent overload of a given hold has been known to occur. For a large bulk carrier such a
discrepancy can amount to 5,000 tons of cargo in a hold. The magnitude of forces and stresses that
can develop during cargo handling can be very significant, and marginal errors in loading can be
catastrophic.

The importance of controlling the loading and discharging in the proper sequence so as not to
accidentally overload the ship is extremely important. Bulk carriers have broken their backs due to
improper cargo loading and discharging of holds. To increase the safety during cargo handling,
loading Instruments are required for all bulk carriers of 150 meters and above. Existing single skin
and new bulk carriers are to have a loading manual with typical loading and unloading sequences.
9 DOUBLE HULL BULK CARRIERS

Another approach to increasing the structural safety of bulk carriers is to consider the double hull bulk
carrier. Some of the structural benefits of a double sided bulk carrier when compared to a single side
skin bulk carrier are that the double side eliminates the exposed, damage-prone side frames and their
end attachments. It also protects against corrosion and mechanical damage