Green Tribology - The Sustainable Design of Lifeboat Launch Systems
Submitting InstitutionBournemouth University
Unit of AssessmentGeneral Engineering
Summary Impact TypeTechnological
Research Subject Area(s)
Engineering: Materials Engineering
Summary of the impact
Royal National Lifeboat Institution (RNLI) lifeboats attend over 15,000
incidents annually with an average of 22 people rescued daily. Previously
friction and wear on launch slipways adversely impacted safe lifeboat
launching, costing the RNLI up to £260k/year. Lifeboat crewmen would
address this issue by applying a layer of grease along the slipway, but
repeated use had both safety and environmental implications. In 2005 this
prompted the RNLI to draw on Bournemouth University's (BU) extensive green
tribology expertise to find a solution. Collaboration between BU and the
RNLI led to the redesign of slipway panels to double their life-span and
switch from grease to a water lubrication system. As well as safety and
environmental benefits, this saves the charity £1 million over a 5 year
term, allowing resources to be focused on life-saving.
Green tribology provides answers to friction and wear problems within an
ecological and environmentally sound context. BU's research in this area
began in 1998 with a combined EPSRC and BP Castrol grant (G1) aimed at
informing industry of optimal design and effective fluid viscosities for
environmentally acceptable refrigerants (P1). This work received "tending
towards outstanding" and "internationally leading" for three categories
within the Grant Review. This original research provided the foundation
for further research and impacts over the next 15 years, based on green
tribology, which at the time was a new concept.
The body of green tribology research, including hermetic compressors;
combining heat and power (CHP) systems; refrigerants; lubricants;
cavitation erosion and sliding contact wear effects contributed to the
growing knowledge base within the Sustainable Design Research Centre
(SDRC) at BU (G6). Specifically, green tribology's role in reducing the
environmental and economic impact within mechanical systems has received
international acclaim (P3).
The purpose of the EPSRC CASE award in 2004-7 (G3) was to work with the
RNLI to address increasing problems of wear on the slipways. Slipway
linings were found to suffer high wear and friction, adversely impacting
safe lifeboat launching and costing the RNLI up to £260,000/year.
Following the introduction of the new heavier `Tamar' class lifeboat in
2006, the problem worsened with slipway panels wearing out in as little as
two weeks. Lifeboat crewmen would address this issue by applying a layer
of grease along the slipway, but the repeated use of this had safety and
In 2004 Thomas (BU 2010 to present) undertook research, supervised by
Hadfield (BU 1997 to present), as part of a CASE award studentship (G3).
Thomas designed two novel test-rig contact conditions specifically for the
slipway contact scenario. These incorporated real-world factors, such as
dwell times and external contamination. BU invested in new analysis
equipment to evaluate the results, including the Zygo profilometer and
light microscope upgrades. Thomas applied wear modelling techniques using
bespoke Finite Element software in order to link the implications of the
lab tests to the real-world case, demonstrating good correlation with the
observed real-world effects (P4-P6).
Specifically, Thomas analysed the contact conditions between the 15cm
wide keel of a 35 tonne lifeboat during a 45kph launch. This required the
development of a new multi-disciplinary approach using aspects of
tribology, finite element analysis, life cycle analysis and real world
data collection, with experimental results combined with real slipway
experience and computer simulations.
The data collected indicated that the reliability of lifeboat slipways
could be greatly increased by ensuring the slipway panels were well
aligned along the length of the slipway. It also showed a small change to
the panel geometry to incorporate a chamfer significantly reduced wear
development and the adverse effects of panel misalignments on launch and
The project showed that it was feasible to substitute the currently used
marine grease lubrication with biodegradable grease, which would reduce
the effects of grease bioaccumulation at the base of the slipway. The
research also proposed the use of a novel water lubrication system instead
of grease directly applied to the slipway, with the potential to greatly
reduce both the operational costs and the environmental impact of slipway
Furthermore, the RNLI commissioned Hadfield and Thomas to undertake
research into alternative slipway materials in 2009. Formal slipway panel
design and fitting guidelines were published for use with the RNLI
shoreworks team (R1).
The project has helped to establish on-going research collaboration
between BU and the RNLI with a jointly funded PhD into marine engine
condition monitoring completed in 2011 (G6).
References to the research
P1. Ciantar, C., Hadfield, M., Smith, A.M. and Swallow, A. (1999).
The influence of lubricant viscosity on the wear of hermetic compressor
components in HFC-134a environments. Wear, 236(1-2), 1-8. DOI:
P2. Howarth, G. and Hadfield, M.A. (2006). Sustainable product
design model. Materials and Design, 27(10), 1128-1133. DOI:
P3. Tzanakis, I., Hadfield, M., Thomas, B., Noya, S.M., Henshaw,
I. and Austen, S. (2012). Future perspectives on sustainable tribology. Renewable
and Sustainable Energy Reviews, 16(6), 4126-4140. DOI:
P4.Thomas, B., Hadfield, M. and Austen, S. (2010). Wear and
Friction Modeling on Lifeboat Launch Systems. Tribology Transactions,
53(4), 584-599. DOI: 10.1080/10402001003602779
P5. Thomas, B., Hadfield, M. and Austen, S. (2009). Experimental
Wear Modelling of Lifeboat Slipway Launches. Tribology International,
42(11-12), 1706-1714. DOI: 10.1016/j.triboint.2009.04.043.
P6. Thomas, B., Hadfield, M. and Austen, S. (2009). Wear
observations applied to lifeboat slipway launches. Wear, 267(11),
2062-2069. DOI: 10.1016/j.wear.2009.08.008.
G1. 1998-2001: Hadfield, M. (Award Holder and PI) (DAK Z28X),
EPSRC (GR/L74972/01), Managed Programme `Design for Whole Life Cycle'. Sustainable
Development of Mechanical Systems using replacement environmental
acceptable refrigerants (three-year post-doc.). £108K (£120K).
G2. 2000-2005: Hadfield, M. (Award Holder) (DAJZ15), Royal Academy
of Engineering. Sustainable development education — visiting
professor scheme. £97K.
G3. 2004-2007: Hadfield, M. (Award Holder and PI) (DAK Z71), EPSRC
and RNLI CASE award. Sustainable design of lifeboat launching systems.
G4. 2007-2010: Hadfield, M. (Award Holder and PI) (DAK G19X),
Energetix Group. Tribological study of new micro-generation system.
G5. 2001-2004: Hadfield, M. (Award Holder and PI), EPSRC (Quota
Award for Grant GR/L74972/01). Sustainable design of sliding contact
durability. Fully funded studentship, estimated value of £45k for
fees and bursary.
G6. 2008-2-11: Hadfield, M. (Award Holder and PI) (DAE G03X),
EPSRC and RNLI (CASE). Durability of Hydraulic Components in Marine
Launching Equipment under Extreme Operating Conditions. £104K.
Details of the impact
RNLI lifeboats attend over 15,000 incidents annually, with an average of
22 people rescued daily. As time is of the essence in life-threatening
incidents in the sea, an immediate response with minimum reaction time is
In 2008 BU prepared a slipway Guidance Design Documentation for the RNLI,
resulting from the EPSRC CASE award (R1). The document was a good practice
design guide for implementation by RNLI technical staff. The new
water-based slipway system identified has been implemented across 38% of
RNLI lifeboat stations since 2008. The research has led to improvements in
crew safety and RNLI launch reliability, as well as reducing maintenance
down-time and machine failure. An increased number of standby lifeboats
are now ready to interfere/engage, with the ultimate goal of ending the
preventable loss of life at sea. All this has been achieved alongside the
considerable cost savings of ~£200k per year as detailed below. The RNLI's
head of engineering support (R2) is an author on publications P3-6, which
corroborate the impact claims.
Once fully implemented across the slipway network, the combined effects
of the research allows the RNLI to save up to £52k in lubricant costs and
a further £143k in material replacement costs (P3). This equates to a
saving of almost £1 million over a 5 year term. With a 2011 combined
budget of just £140m (R3) across the entire UK lifeboat operations solely
provided by charitable donations, this systemic saving is crucial to the
These savings are used to contribute to the on-going process of
modernising the RNLI network as a whole. The RNLI's head of engineering
support, Steve Austin, states: "The findings of the specific research are
extremely valuable to the RNLI as they outline improvements that can be
made to produce more efficient, durable and cost-effective slipways from
which to launch and recover the lifeboats" (P3, R4 & R2).
The research has also shown that the improved fitting criteria and a
modified panel design can reduce the high wear and friction effects. This
philosophy is now codified in three related volumes of slipway panel
design and fitting guidelines. These were published in 2008 and are used
by the RNLI (R1). Slipway lining panels' lifespan increased by over 100%
through better panel fitting criteria and modified panel geometry (P4
& P5). The RNLI has adopted these panel redesigns and fitting criteria
on all their new slipways. Since 2008 the new slipway lining material
identified in the research has been fitted to the new and newly
refurbished slipway stations. This includes Tenby, Padstow and Sennen Cove
among others (R2).
The recommended slipway lining materials are being phased in across the
UK slipway station network over the next few years, coinciding with the
simultaneous roll-out of the new Tamar lifeboat. Currently around 38% of
RNLI slipway stations use the new water lubrication system. Durability of
the panels is increased while service and maintenance time is
In response to the research results the RNLI have stopped using grease to
lubricate the slipways. Instead they have adopted the automated
water-based system BU advised. Since 2010 the RNLI has applied this across
their slipway network, preventing the release of grease from the slipway
into the surrounding marine environment. Once fully adopted this will
result in the removal of 500+ litres of marine grease per annum from the
local marine environment with a consequent saving in carbon emissions of
~740kg CO2 p.a.
Further environmental benefits include the reduction of carbon emissions
from material wear by 45% alongside with other useful environmental
savings due to reduced maintenance costs (P3).
Crewman Safety Impact
The automated water-based system has removed the need for a crewman to
descend the slipway during lifeboat operations and has correspondingly
improved crew safety on lifeboat slipways. The reliability of slipway
launches has also increased.
Additionally, testimonials from individual lifeboat personnel confirm
that the use of the automated water based system reduced the risk exposure
of the volunteer lifeboat crew at each slipway station. This allows the
safe continuation the RNLI's crucial role in preserving life along the
coast of the UK and Ireland (R5).
Further societal benefits include the continued on-going reliability and
security of vital life-saving services through the reduction in
maintenance down-time and machine failure.
Wider Research Impact
The research was presented at a number of international conferences
including at the House of Commons as part of the `Reception for Younger
Engineers at the House of Commons' (R6) and was short-listed at the Times
Higher Education (THE) Awards 2010 in the category of `Outstanding
Contribution to Innovation and Technology'. This award specifically
highlighted BU's role in reducing environmental impact and costs (R7).
The research methodology developed during this project has many potential
uses in other tribological contact situations, including oil rig rescue
craft, overseas slipway lifeboats and cradle-launched beach rescue craft.
The research is also relevant to applications involving sliding contacts
along any tiled or grooved surfaces, including tyre friction along paved
roads and spacecraft heat shields.
The application of the research within the RNLI has already had
significant economical, operational and environmental benefits, as well as
facilitating improvements to crewman safety. The £1 million saved over a
five year period frees up resources to be used in the 15,000 incidents and
rescues the charity attends each year.
Sources to corroborate the impact
R1. RNLI: Guidance Design Documentation resulting from EPSRC CASE
project. BU account reference DAK K43.
R2. RNLI's head of engineering support. Contact details available.
R3. RNLI Annual Report and Accounts 2011. Available from:
R4. BBC Radio article: RNLI Slipway Research. Available
R5. RNLI news story: Lifeboat project ready for awards splash.
R6. Reception for Younger Engineers at the House of Commons at
Portcullis House, Westminster, 2005.
R7. THE Awards shortlist in the category of `Outstanding
Contribution to Innovation and Technology', 2010.