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The University of Southampton

Research project: Security of boat moorings and harvesting their energy

Currently Active: 

Understanding the motion and security of moored floating bodies, including their potential for energy extraction.

The Royal National Lifeboat Institution (RNLI) is an independent charity funded by voluntary contributions with 236 stations around the U.K. The video below shows their volunteer crew in action.

During 2012 they launched on 8,346 occasions which resulted in 7,636 rescues and 328 saved lives. The institution is committed to providing lifeboat cover out to 100 miles off the coast and reach “at least 90% of casualties within 10 miles of their stations in all-weathers within 30 minutes.” In order to achieve these targets 20 all-weather lifeboats are moored permanently afloat at lifeboat stations where a pontoon or land based facility is unavailable (Fig.1). To date their location and design has been based largely on intuition and local knowledge of wind, tide, current, fetch and topography. Since the loss of a lifeboat, whilst secured on its mooring, is unacceptable a method is needed to improve our understanding of how such mooring can fail and so take steps to prevent such an occurrence. The expansion of offshore oil and gas extraction has led to the publication of experiments investigating the mooring design and motions of large scale tankers stationed at single point moorings in deep water. To date there is a lack of published data on the efficacy of SPM of vessels of lengths less than 20 m located in shallow coastal depths up to 10 m. This research begins to address the complex mechanics of a SPM through a series of experimental investigations, in current and waves, investigating the effect on the motion of the vessel of changes in mooring line length, buoy scale and buoy shape.

RNLI lifeboat at a single point mooring
Fig. 1 RNLI lifeboat at a single point mooring


Aims and Objectives:

This project is aimed at understanding the patterns of behaviour of a lifeboat and buoy stationed at its mooring. These aims will be achieved through a combination of the following objectives:

(1) Recording the motions of a model lifeboat interacting with its mooring buoy at different scales in current and wave experiments.

(2) Examining the effect of mooring line length, buoy shape and size on the interactions of boat and buoy.

(3) Investigation of full scale motion at a mooring in Yarmouth Harbour.


Outcomes and novelty:

  • An improved understanding of the motion and mooring line loads experienced by a Single Point Moored lifeboat in coastal harbours in order to reduce the uncertainty surrounding design and configuration and improve efficiency.
  • Provision, of currently unavailable, experimental data on the effects of changes in mooring line length, buoy shape and size in terms of providing energy harvesting at SPM from the mooring buoy.
  • In-situ data from a lifeboat at a SPM.

Associated research themes

Royal National Lifeboat Institution Advanced Technology Partnership on maritime engineering and safety (RNLI ATP)

Related research groups

Maritime Engineering
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