Trelleborg Marine Systems
Ship TablesBerthing ModesCoef cientsBerth LayoutPanel DesignMaterialsFender TestingRef. M1100-S12-V1-3-EN
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Fenders must reliably protect ships, structures and themselves. They must work every day for many years in severe environments with little or no maintenance.
As stated in the British Standard, fender design should be entrusted to appropriately qualifi ed and experienced people. Fender engineering requires an understanding of many areas:
Ship technology Civil construction methods Steel fabrications Material properties Installation techniques Health and safety Environmental factors Regulations and codes of practice
Using this guide
This guide should assist with many of the frequently asked questions which arise during fender design. All methods described are based on the latest recommendations of PIANC*
as well as other internationally recognised codes of practice.
Methods are also adapted to working practices within Trelleborg and to suit Trelleborg products.
Further design tools and utilities including generic specifi cations, energy calculation spreadsheets, fender performance curves and much more can be downloaded from the Trelleborg Marine Systems website (www.trelleborg.com/marine).
These guidelines do not encompass unusual ships, extreme berthing conditions and other extreme cases for which specialist advice should be sought.
Codes and guidelines
ROM 0.2-90 1990 Actions in the Design of Maritime and Harbor
BS6349 : Part 4 : 1994 1994 Code of Practice for Design of Fendering and
EAU 1996 1996 Recommendations of the Committee for
PIANC Bulletin 95 1997 Approach Channels A Guide to Design
Supplement to Bulletin No.95 (1997) PIANC
Japanese MoT 911 1998 Technical Note of the Port and Harbour
Research Institute, Ministry of Transport, Japan
No. 911, Sept 1998
* PIANC 2002 2002 Guidelines for the Design of Fender Systems :
2002 Marcom Report of WG33
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Symbol Defi nition UnitsB Beam of vessel (excluding beltings and strakes) mC Positive clearance between hull of vessel and face of structure mCB Block coeffi cient of vessels hull CC Berth confi guration coeffi cient CE Eccentricity coeffi cient CM Added mass coeffi cient (virtual mass coeffi cient) CS Softness coeffi cient D Draft of vessel mEN Normal berthing energy to be absorbed by fender kNmEA Abnormal berthing energy to be absorbed by fender kNmFL Freeboard at laden draft mFS Abnormal impact safety factor H Height of compressible part of fender mK Radius of gyration of vessel mKC Under keel clearance mLOA Overall length of vessels hull mLBP Length of vessels hull between perpendiculars mLS Overall length of the smallest vessel using the berth mLL Overall length of the largest vessel using the berth mM Displacement of the vessel tonneM50 Displacement of the vessel at 50% confi dence limit tonneM75 Displacement of the vessel at 75% confi dence limit tonneMD Displacement of vessel tonneP Fender pitch or spacing mR Distance from point of contact to the centre of mass of the vessel mRF Reaction force of fender kNV Velocity of vessel (true vector) m/sVB Approach velocity of the vessel perpendicular to the berthing line m/s Berthing angle degree Defl ection of the fender unit % or m Hull contact angle with fender degree Coeffi cient of friction Velocity vector angle (between R and V) degree
Rubber fender Units made from vulcanised rubber (often with encapsulated steel plates) that absorbs energy by elastically deforming in compression, bending or shear or a combination of these effects.
Pneumatic fender Units comprising fabric reinforced rubber bags fi lled with air under pressure and that absorb energy from the work done in compressing the air above its normal initial pressure.
Foam fender Units comprising a closed cell foam inner core with reinforced polymer outer skin that absorb energy by virtue of the work done in compressing the foam.
Steel Panel A structural steel frame designed to distribute the forces generated during rubber fender compression.
Commonly used symbols
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10 reasons for quality fendering
Safety of staff, ships and structures Much lower lifecycle costs Rapid, trouble-free installation Quicker turnaround time, greater effi ciency Reduced maintenance and repair Berths in more exposed locations Better ship stability when moored Lower structural loads Accommodate more ship types and sizes More satisfi ed customers
There is a simple reason to use fenders: it is just too expensive not to do so. These are the opening remarks of PIANC* and remain the primary reason why every modern port invests in protecting their structures with fenders.
Well-designed fender systems will reduce construction costs and will contribute to making the berth more effi cient by improving turn-around times. It follows that the longer a fender system lasts and the less maintenance it needs, the better the investment.
It is rare for the very cheapest fenders to offer the lowest long term cost. Quite the opposite is true. A small initial saving will often demand much greater investment in repairs and upkeep over the years. A cheap fender system can cost many times that of a well-engineered, higher quality solution over the lifetime of the berth as the graphs below demonstrate.
Capital costs Maintenance costs
10 20 30 40Service life (years)
Purchase price+ Design approvals+ Delivery delays+ Installation time+ Site support= Capital cost
Wear & tear+ Replacements+ Damage repairs+ Removal & scrapping+ Fatigue, corrosion= Maintenance cost
Capital cost + Maintenance cost = FULL LIFE COST
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type(s) of cargo safe berthing and mooring
better stability on berth reduction of reaction force
Calculation of berthing energyCM virtual mass factorCE eccentricity factor
CC berth confi guration factorCS softness factor
location of mooring equipment and/or dolphins
strength and type of mooring lines
pre-tensioning of mooring lines
Assume fender system and type
Computer simulation (fi rst series)
check vessel motions in six degrees of freedomcheck vessel acceleration
check defl ection, energy and reaction forcecheck mooring line forces
Computer simulation (optimisation)
Calculation of fender energy absorptionselection of abnormal berthing safety factor
Selection of appropriate fenders
Determination of:energy absorption reaction force defl ection
environmental factors angular compression hull pressure
frictional loads chains etc
Check impact on structure and vesselhorizontal and vertical loading chance of hitting the structure (bulbous bows etc)face of structure to accommodate fender
implications of installing the fenderbevels/snagging from hull protrusionsrestraint chains
Final selection of fenderdetermine main characteristics of fenderPIANC Type Approved verifi cation test methods
check availability of fender track record and warranties future spares availability fatigue/durability tests
berthing procedures frequency of berthing limits of mooring and operations (adverse weather)range of vessel sizes, types special features of vessels (fl are, beltings, list, etc)allowable hull pressures
light, laden or partly laden ships stand-off from face of structure (crane reach)fender spacing type and orientation of waterfront structurespecial requirements spares availability
wind speed wave height current speed
topography tidal range swell and fetch
temperature corrosivity channel depth
Design criteriacodes and standards design vessels for calculations normal/abnormal velocity maximum reaction force friction coeffi cient desired service life
safety factors (normal/abnormal) maintenance cost/frequency installation cost/practicality chemical pollution accident response
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THE DESIGN PROCESS
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Many factors contribute to the design of a fender:
ShipsShip design evolves constantly shapes change and many vessel types are getting larger. Fenders must suit current ships and those expected to arrive in the foreseeable future.
StructuresFenders impose loads on the berthing structure. Many berths are being built in exposed loca