CRNAVIES

Running

The Cooperative Research Navies (CRNAV) consortium was established in 1990 to study the mechanisms of capsizing and to develop guidelines for safe ship design and operation at sea, including extreme conditions.

BACKGROUND

Navy ships have been designed and operated for the past 50 years in accordance with empirically based stability criteria which were derived for wall-sided and flared monohull vessels of World War II vintage. Existing ship stability criteria do not adequately address dynamic stability, nor the stochastic nature of the wave environment. These criteria are typically based on hydrostatics and include margins, which are only approximate means of accounting for ship dynamics. The stability criteria do not account for a ship’s dynamic behaviour in extreme seas. Even modern hull forms may experience large roll angles in extreme sea conditions.

As warships must be able to operate in high sea states and at high speeds, this problem is of particular concern to navies. Stability requirements can have a major impact on decisions made during the design of these ships, such as the location of the center of gravity. In addition, such criteria dictate the inherent levels of safety against capsizing. Therefore, there is a clear need to develop dynamic stability criteria for practical design purposes on a rational basis.

PARTICIPANTS AND ASSOCIATE MEMBERS

  • Canadian Navy (DMSS, Ottawa and DRDC-Atlantic, Dartmouth)
  • Ministry of Defence, DGA Hydrodynamics (Val de Reuil)
  • Royal Australian Navy; Defence Science Technology Group (Department of Defence, Melbourne)
  • Royal Netherlands Navy (Department of Defence, Utrecht)
  • Royal UK Navy (UK MoD, Bristol and QinetiQ, Haslar)
  • U.S. Coast Guard (Engineering Logistics Center, Baltimore)
  • MARIN (Wageningen, the Netherlands)
Participants contribute their expertise and technology to the group's research efforts. MARIN provides the CRNAV chairmanship and secretariat, as well as overall project management. Members of the CRNAV consortium have access to protected project pages and documents. If you are a member but you do not have a username/password, please send an e-mail to crnav@marin.nl

Contact

Contact person photo

Frans Kremer

Defence Programme Manager

Working groups

CRNAV

The Cooperative Research Navies (CRNAV) started in 1989 with the intention to investigate the dynamic stability of naval vessels. The main activities comprise the following areas:
  • Prediction and validation of extreme motions for intact and damaged ships.
  • Capsize risk assessment for intact and damaged frigates.
  • Operational guidance and training.
  • FREDYN software developments and deliverables.
Participating Navies have formed the Naval Ship Stability Working Group (NSSWG) to develop more rational based dynamic stability criteria than presently available. The Operator Guidance Training & Working Group (OGTWG) was formed to include operational information in capsize risk assessment studies and to further introduce heavy weather training on bridge simulators linked to FREDYN.

In principle the research is carried out by the member organizations only. The results of the investigations are the sole property of the CRNAV members. The strictest confidentiality is maintained and results may be published only after approval of the CRNAV. Each organization may decide to continue the cooperation or to withdraw at the conclusion of each three-year period. Overhead costs are kept to a minimum.The research program of CRNAV is broadly defined for three year periods (phases) and closely defined for each coming calendar year. The work includes Fundamental, Design, and Operations oriented projects. Fundamental work deals with the further development and validation of FREDYN for prediction of extreme motions for intact and damaged ships. Design orientated work focuses on capsize risk assessment of intact and damaged ships, while Operations oriented projects deal with operational guidance and training.The CRNAV group consists of the following members (2015-2017 period) with voting rights:
  • Canadian Navy (DMSS, Ottawa)
  • Ministry of Defence, DGA Hydrodynamics (Val de Reuil)
  • Australian Navy; Defence Science Technology Group (Department of Defence, Melbourne)
  • Royal Netherlands Navy (Department of Defence, The Hague)
  • Royal UK Navy (UK MoD, Bristol)
  • Maritime Research Institute Netherlands (MARIN, Wageningen)
The CRNAV group further consists of the following associated members (2015-2017 period):
  • DRDC Atlantic, Halifax, Canada
  • QinetiQ, Gosport, UK
In principle all organisations interested in the design and operation of naval ships may become member of the CRNAV. However, new members are accepted only by unanimous agreement of the existing members.

NSSWG

The NSSWG was established in 1999 as a sister group to the CRNAV. Its membership consists of representatives from a number of Navies. They are supported by guest members from associated research organisations. This group is not directly funded but is supported by the CRNAV group as such membership is limited to full members of the CRNAV.The objective is to develop a shared view on the future of naval stability assessment and develop a draft set of stability guidelines which can be utilised by the participating navies at their discretion.’This working group is considering the following issues:
  • All aspects of stability.
  • Develop a view on strengths, weaknesses and interpretations of existing naval stability standards.
  • Evaluate the applicability of IMO stability requirements.
  • Develop a set of recommendations for the use of dynamic stability analysis a rational stability standard.
  • Develop a set of recommendations on risk based approaches.
  • Develop a draft Naval Stability Standard Guidelines incorporating the working points above.
  • Develop operator guidance on heavy weather ship handling.
This working group consists of the following members:
  • Department of Defence (Australia)
  • Department of National Defence (Canada)
  • Ministere de la Defense (France)
  • Ministerie van Defensie (Netherlands)
  • Ministry of Defence, DPA (UK)
  • United States Coast Guard (USA)
Guest members:
  • Defence Research & Development Centre - Atlantic ( Canada )
  • Maritime Research Institute ( Netherlands )
  • QinetiQ ( UK )

OGTWG

The current guidelines for ship handling in severe seaway conditions are based on practical knowledge and rules of thumb attained over decades of experience with conventional naval ships. While this has worked in the past to ensure that correct ship handling decisions are made while in severe seaway conditions, at sea time and resultant practical ship handling opportunities for watch officers are diminishing in today’s navies. There is a heightened need to explore and develop new methodologies for training of watch officers, CO’s and XO’s in ship handling in the severe seaway environment. In addition, recent simulation studies have shown that some traditional guidance may actually put ships at increased risk of capsize. The Operator Guidance, and Training Working Group has been formed to examine these issues and develop a shared perspective for reference by member navies in addressing training, technology and operator guidance needed to manage the risk of capsize at sea.The OGTWG aims to develop a shared view on the future of naval stability operator guidance and training for severe seaway conditions. The group is to develop a draft set of Naval Stability Operator Guidance and Training guidelines which can be utilised by the participating navies at their discretion.

The OGTWG is considering the following working points:
  • All aspects of ship handling in severe seaways related to capsize risk management.
  • Collate and develop a view on strengths, weaknesses and interpretations of existing heavy weather operator guidance.
  • Assess requirements for training and evaluate ship use of simulators as training tool.
  • Develop a set of recommendations for the use of heavy weather Naval Stability Operator Guidance and Training.
  • Develop a draft Naval Stability Operator Guidance and Training Guidelines incorporating the working points above.