Shipowners want stronger ships. Regulators want stronger ships. Both want new requirements to apply across the industry - a level playing field. In response, the 10 Members of the International Association of Classification Societies
(IACS) are progressing technical programs that will lead to more uniform scantling requirements and wastage limits for bulk carriers, oil tankers
and, eventually, other ship types.
At Posidonia, IACS Chairman Igor Ponomarev outlined work in progress that will culminate in new Unified Requirements (URs) for stronger vessels. For bulk carrier newbuildings
, a major initiative - concerned with strength and safe operation - consists of new, harmonized design loading conditions and notations so as to provide increased transparency of the operating capabilities and limits of bulk carriers. This work, which has been developed in response to and in communication with owners’ associations, is near to completion. IACS Council
is considering a new UR which, when adopted, will be published on the IACS Website, that will specify the following notations and annotations:
BC-A: for bulk carriers designed to carry dry bulk cargoes of cargo density 1.0 tonne/m3 and above with specified holds empty in addition to BC-B conditions
BC-B: for bulk carriers designed to carry dry bulk cargoes of cargo density 1.0 tonne/m3 and above with all cargo holds loaded in addition to BC-C conditions
BC-C: for bulk carriers designed to carry dry bulk cargoes of cargo density less than 1.0 tonne/m3
The new UR provides for additional notations and annotations giving further detailed
description of limitations to be observed during operation as a consequence of the loading
condition applied during the design in specified cases. In addition, the UR will clarify the
general design loading conditions for all notations and specify ballast conditions.
This initiative, concerned with newbuildings, complements IACS’ eight-point action plan for
existing bulk carriers which, inter alia, accelerates the schedule for strengthening of the
foremost cargo hold’s transverse corrugated bulkhead and double bottom, addresses the
strength of the side structure in cargo holds, increases requirements for forward hatch covers,
requires the installation of improved bulwarks or breakwaters when ships are not fitted with a
forecastle and further increases the requirements of the IACS Enhanced Survey Program
earlier in the service life of these ships. Some of the requirements in this package will also
apply to new tonnage. For example, in the case of newbuildings, it is expected that forecastles
will be required.
Meanwhile, IACS’ full reassessment of the strength requirements for hatch cover scantlings
(UR S21) – the central recommendation of the Re-opened Formal Inquiry into the loss of the
bulk carrier Derbyshire
, is now well advanced. Completion of this work is expected in August.
The results will be submitted to the IMO.
Work is also progressing on a longer term project aimed at increased harmonization of
scantling requirements for bulk carrriers and tankers. As a first step, each IACS member is
performing scantling evaluations for two “study ships” – a VLCC and a Panamax bulk carrier –
to identify the minimum scantlings required to satisfy its Rules. These comparative results will
identify the areas of substantial similarities and differences amongst IACS members. The
comparative study work is well under way and should be completed later this year. Work will
then focus on developing a refined plan for the development of new unified requirements and
the formulation of unified minimum scantling requirements for midship scantlings for tankers
and bulk carriers. The net scantling approach will be used in the development of these new
unified requirements. In this approach, the minimum required scantling for new construction is
the net scantling plus a corrosion addition.
The IACS Chairman said: “This is an extremely important advance. We hope to have some of
the new higher strength, minimum scantling URs ready for consideration by IACS Council by
mid-2004. Work in this area is extremely challenging, yet progress is being made. The
significance of the project centres on the fact that, at present, each classification society
applies its own structural evaluation criteria to determine minimum scantling requirements.
Although there are URs governing longitudinal strength that are currently applied by all IACS
societies, the minimum scantlings are, at present, sufficiently different to encourage efforts by
some shipyards to seek approval of ever lower steel weights
for new construction.
“Safety may be compromised if commercial parties remain free to ‘shop around’ for lower cost
solutions for newbuildings which, in some cases, can undermine prudent standards of
structural strength. The new IACS URs will
largely remove the potential for such undesirable
practices. In taking action, we are responding decisively to calls by shipowners’ associations
and other parties for an end to competition on standards to achieve ever lower steel weights.”
Other IACS initiatives now in progress and concerning vessel strength include:
• A comprehensive revision of UR S11, the longitudinal strength standard with a net
scantling approach. Work in this area has the aim of developing requirements for hull
girder loads and yielding checks for bending moments and shear forces, together with
ultimate strength checks. This task is targeted for completion by the third quarter of next
• New specifications for HT 40 hull structural steels of thicknesses up to 100 mm. The
specifications form part of a new revision of UR W11, which is expected to be adopted
this month by the IACS Council.
A number of these projects are being taken forward by IACS’ Working Party (Strength). In due
course, the Working Party will also submit proposals for a uniform, transparent approach to
allowable wastage allowances to achieve uniform scantling renewal requirements amongst
IACS societies for use with the new unified minimum required scantlings for new construction.
The proposals will be considered for adoption by the IACS Council and for incorporation into
the Rules of IACS societies.
Igor Ponomarev says
: “The uniform wastage allowances will be based on an analysis of over
half a million sets of corrosion data concerning the structural elements of bulk carriers and oil
tankers, contributed by all IACS societies. The collation and analysis of the data sets was
undertaken within a project that began in 1995 and predates the current initiatives for stronger
The IACS Chairman concludes: “In all areas concerned with the strength of vessels, IACS will
continue in its leadership role and will continue to support the IMO’s important work in many
related areas. IMO Secretary-General William O’Neil recently stressed the importance of the
industry moving ahead on a joint basis. We share this objective.”