Background

Background

One main issue discussed at the 61st  Marine Environment Protection Committee of IMO (MEPC 61) was  the safety  implications  of adopted  EEDI  requirements  on  ship’s  manoeuvrability  in adverse conditions. Some flag states argued for reducing the installed power to achieve the required EEDI, thus allowing ship designers to opt for lower design speed, which is also beneficial for fuel saving (‘slow  steaming’).  To  avoid  the  negative  effects  on  safety,  such  as  under-powered  ships,  IACS societies proposed to add a provision to the draft regulations text (MEPC 61/5/32), namely

“For each ship to which this regulation applies, the installed propulsion power shall not be less than the propulsion power needed to maintain the manoeuvrability of the ship under adverse conditions as defined in the guidelines to be developed by the Organization”

It was agreed to incorporate this in the Revised MARPOL Annex VI, Chapter 4, Regulation 21.5. Following this, IACS was tasked to develop such guidelines and the result of the work was presented at the 62nd   session of IMO MEPC, ref. documents  MEPC 62/5/19 and MEPC 62/INF.21. These documents presented draft interim guidelines for determining “Minimum propulsion power to ensure safe manoeuvring in adverse conditions”. To emphasize the difficulties faced during this work, the following statement was also included in document MEPC 62/5/19:

For manoeuvring in adverse conditions, no standards are known to exist. In particular:

1.   no  standard  manoeuvre(s)  exists  which,  if  being  carried  out  successfully  in   adverse conditions,  could  demonstrate  that  the  ship  is  capable  of  safe  manoeuvring  in   these conditions;

2.   “adverse conditions” are not defined;

3.   model experiments with simulated adverse waves and wind are possible, but may not  be practicable for routine ship design purposes, as few such facilities exist;

4.   numerical simulation tools are not considered to be mature enough for routine ship design purposes,  as recently  reported  by the  Manoeuvring  Committee  to  the  25th  International Towing Tank Conference in 2008.

It was proposed to adopt a two phase approach to establish the required minimum power:

1.   a simplified assessment and,

2.   a comprehensive assessment.

The simplified assessment assesses only the minimum advance speed, which will be achieved in co- aligned head waves and wind, while the comprehensive  assessment implies checking the turning ability, course keeping and the ability to advance in adverse conditions. Document MEPC 62/5/19 has also proposed to choose between two minimum advance speeds: 2 or 4 knots.

Following additional studies, which were justified by the complexity of the subject, a new proposal for the guidelines was very recently presented by IACS at MEPC 64 in October 2012, ref. documents MEPC 64/4/13 and MEPC 64/INF.7.

MEPC 64/4/13 proposes a three phase approach,  including a minimum power line approach for further   simplification   of  the  assessment.   The  simplified   assessment   and  the  comprehensive assessment have essentially been maintained as proposed at MEPC 62 but with a few amendments.

Despite some progress, the definitions of adverse conditions and required advance speed remain disputable and will be updated in the frame of expected new improved interim guidelines applicable to  the Phase 0 of the EEDI (ref. revised MARPOL Annex VI Ch.4 Reg.21 for definition of EEDI application phases ), scheduled to be introduced at MEPC 65 in May 2013.

 Development  of the final guidelines  for minimum  propulsion  power will continue subsequent  to MEPC 65. The final guidelines will be applicable to Phase 1, 2 and 3 of the EEDI framework.

 IACS encountered difficulties during the development of the guidelines due to insufficient State of the Art in related scientific disciplines and lack of sufficient experimental data on manoeuvrability of various  types of ships in adverse conditions.  Moreover,  there is no satisfactory  feedback  on the situations faced by the shipping industry when operating in adverse conditions and little knowledge about  the  possible  connection  between  lack  of  manoeuvrability  in  adverse  conditions  and  ship accidents.

 The SHOPERA project thus aims to provide a substantial contribution to the knowledge and State of the Art in this area and to propose solutions to the questions opened by the work carried out by IACS. It should be noted that three (3) out of four (4) classification societies involved in the work carried out by IACS, namely GL, DNV and LR, are main partners of the SHOPERA consortium. To this end, a consortium  was  put  together  representing  the  whole  spectrum  of  stakeholders  in  the  European maritime  industry  and  with  superior  expertise  and  scientific  know-how  in  hydrodynamic  tools development, experimental techniques and expertise in optimisation of ship design and operation, as in international maritime rule making. SHOPERA aims to contribute to parallel work at IMO in the same fashion as projects HARDER, SAFEDOR and GOALDS by a consortium comprised to a great extent by the same core partnership.