Trelleborg Marine Systems
Ship Tables
Berthing Modes
Coeffi cients
Berth Layout
Section 12
FENDER DESIGN
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
B
Civil construction methods
B Steel fabrications B Material properties B Installation techniques B
Health and safety
B
Environmental factors
B
Regulations and codes of practice
B
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).
Exceptions
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 Works
†BS6349 : Part 4 : 1994 1994 Code of Practice for Design of Fendering and
Mooring Systems
EAU 1996 1996 Recommendations of the Committee for Waterfront Structures
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
GLOSSARY
Symbol Defi nition Units
B Beam of vessel (excluding beltings and strakes) m
C Positive clearance between hull of vessel and face of structure m
CB Block coeffi cient of vessel’s 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 m
EN Normal berthing energy to be absorbed by fender kNm
EA Abnormal berthing energy to be absorbed by fender kNm
FL Freeboard at laden draft m
FS Abnormal impact safety factor –
H Height of compressible part of fender m
K Radius of gyration of vessel m
KC Under keel clearance m
LOA Overall length of vessel’s hull m
LBP Length of vessel’s hull between perpendiculars m
LS Overall length of the smallest vessel using the berth m
LL Overall length of the largest vessel using the berth m
M Displacement of the vessel tonne
M50 Displacement of the vessel at 50% confi dence limit tonne
M75 Displacement of the vessel at 75% confi dence limit tonne
MD Displacement of vessel tonne
P Fender pitch or spacing m
R Distance from point of contact to the centre of mass of the vessel m
RF Reaction force of fender kN
V Velocity of vessel (true vector) m/s
VB Approach velocity of the vessel perpendicular to the berthing line m/s
α Berthing angle degree
δ Defl ection of the fender unit % or m
θ Hull contact angle with fender degree
μ Coeffi cient of friction –
ϕ 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
WHY FENDER?
10 reasons for quality fendering
Safety of staff, ships and structuresB
Much lower lifecycle costs
B
Rapid, trouble-free installation
B
Quicker turnaround time, greater effi ciency
B
Reduced maintenance and repair
B
Berths in more exposed locations
B
Better ship stability when moored
B
Lower structural loads
B
Accommodate more ship types and sizes
B
More satisfi ed customers
B
‘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
0 20 40 60 80 100 120 140 160 180
Trelleborg
Other
Purchase price
Other costs
10 20 30 40Service life (years)
50 0 100 200 300 400 500 600 700
Trelleborg
Other
Purchase price + Design approvals + Delivery delays + Installation time + Site support = Capital costWear & tear + Replacements + Damage repairs + Removal & scrapping + Fatigue, corrosion
= Maintenance cost
DESIGN FLOWCHART
Functional
type(s) of cargo
B
safe berthing and mooring
B BB better stability on berthreduction of reaction force
Design criteria
Calculation of berthing energy
CM virtual mass factor
CE eccentricity factor
CC berth confi guration factor
CS softness factor
Mooring layout
location of mooring
B
equipment and/or dolphins
strength and type
B
of mooring lines
pre-tensioning of
B
mooring lines
Assume fender system and type
Computer simulation (fi rst series)
Check results
check vessel motions in six
B
degrees of freedom check vessel acceleration
B
check defl ection, energy and
B
reaction force
check mooring line forces
B
Computer simulation (optimisation) Calculation of fender energy absorption
selection of abnormal berthing safety factor
B
Selection of appropriate fenders
Determination of: energy absorption B reaction force B defl ection B environmental factors B angular compression B hull pressure B frictional loads B chains etc B
Check impact on structure and vessel
horizontal and vertical loading
B
chance of hitting the structure
B
(bulbous bows etc) face of structure to
B
accommodate fender
implications of installing the
B
fender
bevels/snagging from hull
B
protrusions restraint chains
B
Final selection of fender
determine main characteristics
B
of fender
PIANC Type Approved
B
verifi cation test methods
B
check availability of fender
B
track record and warranties
B
future spares availability
B fatigue/durability tests B Operational berthing procedures B frequency of berthing B
limits of mooring and operations
B
(adverse weather) range of vessel sizes, types
B
special features of vessels
B
(fl are, beltings, list, etc) allowable hull pressures
B
light, laden or partly laden ships
B
stand-off from face of structure
B
(crane reach) fender spacing
B
type and orientation of
B waterfront structure special requirements B spares availability B Site conditions wind speed B wave height B current speed B topography B tidal range B
swell and fetch
B temperature B corrosivity B channel depth B Design criteria
codes and standards
B
design vessels for calculations
B
normal/abnormal velocity
B
maximum reaction force
B
friction coeffi cient
B
desired service life
B
safety factors (normal/abnormal)
B maintenance cost/frequency B installation cost/practicality B chemical pollution B accident response B
THE DESIGN PROCESS
Many factors contribute to the design of a fender:
Ships
Ship 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.
Structures
Fenders impose loads on the berthing structure. Many berths are being built in exposed locations, where fenders can play a crucial role in the overall cost of construction. Local practice, materials and conditions may infl uence the choice of fender.
Berthing
Many factors will affect how vessels approach the berth, the corresponding kinetic energy and the load applied to the structure. Berthing modes may affect the choice of ship speed and the safety factor for abnormal conditions.
Installation and maintenance
Fender installation should be considered early in the design process. Accessibility for maintenance, wear allowances and the protective coatings will all affect the full life cost of systems. The right fender choice can improve turnaround times and reduce downtime. The safety of personnel, structures and vessels must be considered at every stage – before, during and after commissioning.ENVIRONMENT
Berthing structures are located in a variety of places from sheltered basins to unprotected, open waters. Local
conditions will play a large part in deciding the berthing speeds and approach angles, in turn affecting the type and size of suitable fenders.
Typical berthing locations
Non-tidal basins
With minor changes in water level, these locations are usually sheltered from strong winds, waves and currents. Ship sizes may be restricted due to lock access.
Coastal berths
Maximum exposure to winds, waves and currents. Berths generally used by single classes of vessel such as oil, gas or bulk.
River berths
Largest tidal range (depends on site), with greater exposure to winds, waves and currents. Approach mode may be restricted by dredged channels and by fl ood and ebb tides. Structures on river bends may complicate berthing manoeuvres.
Tidal basins
Larger variations in water level (depends on location) but still generally sheltered from winds, waves and currents. May be used by larger vessels than non-tidal basins.
Tides
Tides vary by area and may have extremes of a few centimetres (Mediterranean, Baltic) or over 15 metres (parts of UK and Canada). Tides will infl uence the structure’s design and fender selection.
HRT Highest Recorded Tide HAT Highest Astronomical Tide MHWS Mean High Water Spring MHWN Mean High Water Neap MLWN Mean Low Water Neap MLWS Mean Low Water Spring LAT Lowest Astronomical Tide LRT Lowest Recorded Tide
Currents and winds
Current and wind forces can push vessels onto or off the berth, and may infl uence the berthing speed. Once berthed, and provided the vessel contacts several fenders, the forces are usually less critical. However special cases do exist, especially on very soft structures. As a general guide, deep draught vessels (such as tankers) will be more affected by current and high freeboard vessels (such as RoRo and container ships) will be more affected by strong winds.
HRT HAT MHWS MHWN MSL MLWN MLWS LAT LRT
STRUCTURES
Features
Design considerations
Open pile jetties
B Simple and cost-effectiveGood for deeper waters
B
Load-sensitive
B
Limited fi xing area for fenders
B
Vulnerable to bulbous bows
B
Low reaction reduces pile
B
sizes and concrete mass Best to keep fi xings above
B
piles and low tide
Suits cantilever panel designs
B
Dolphins
B Common for oil and gas terminalsVery load-sensitive
B
Flexible structures need careful
B
design to match fender loads Structural repairs are costly
B
Few but large fenders
B
Total reliability needed
B
Low reactions preferred
B
Large panels for low hull
B
pressures need chains etc
Monopiles
B Inexpensive structuresLoads are critical
B
Not suitable for all geologies
B
Suits remote locations
B
Quick to construct
B
Fenders should be designed
B
for fast installation
Restricted access means low
B
maintenance fenders Low reactions must be
B
matched to structure Parallel motion systems
B
Mass structures
B Most common in areas with small tidesFender reaction not critical
B
Avoid fi xings spanning pre-cast and
B
in situ sections or expansion joints
Keep anchors above low tide
B
Care needed selecting fender
B
spacing and projection Suits cast-in or retrofi t anchors
B
Many options for fender types
B
Sheet piles
Quick to construct
B
Mostly used in low corrosion regions
B
In situ concrete copes are common
B
Can suffer from ALWC (accelerated
B
low water corrosion)
Fixing fenders direct to piles
B
diffi cult due to build tolerances Keep anchors above low tide
B
Care needed selecting fender
B
spacing and projection
The preferred jetty structure can infl uence the fender design and vice versa. The type of structure depends on local practice, the geology at the site, available materials and other factors.
Selecting an appropriate fender at an early stage can have a major effect on the overall project cost. Below are some typical structures and fender design considerations.
SHIP TYPES
General cargo ship
Prefer small gaps between ship and quay to minimise outreach of cranes.
B
Large change of draft between laden and empty conditions.
B
May occupy berths for long periods.
B
Coastal cargo vessels may berth without tug assistance.
B
Bulk carrier
Need to be close to berth face to minimise shiploader outreach.
B
Possible need to warp ships along berth for shiploader to change holds.
B
Large change of draft between laden and empty conditions.
B
Require low hull contact pressures unless belted.
B
Container ship
Flared bows are prone to strike shore structures.
B
Increasing ship beams needs increase crane outreach.
B
Some vessels have single or multiple beltings.
B
Bulbous bows may strike front piles of structures at large berthing angles.
B
Require low hull contact pressures unless belted.
B
Oil tanker
Need to avoid fi re hazards from sparks or friction.
B
Large change of draft between laden and empty conditions.
B
Require low hull contact pressures.
B
Coastal tankers may berth without tug assistance.
B
RoRo ship
Ships have own loading ramps – usually stern, slewed or side doors.
B
High lateral and/or transverse berthing speeds.
B
Manoeuvrability at low speeds may be poor.
B
End berthing impacts often occur.
B
Many different shapes, sizes and condition of beltings.
B
Passenger (cruise) ship
Small draft change between laden and empty.
B
White or light coloured hulls are easily marked.
B
Flared bows are prone to strike shore structures.
B
Require low hull contact pressures unless belted.
B
Ferry
Quick turn around needed.
B
High berthing speeds, often with end berthing.
B
Intensive use of berth.
B
Berthing without tug assistance.
B
Many different shapes, sizes and condition of beltings.
B
Gas carrier
Need to avoid fi re hazards from sparks or friction.
B
Shallow draft even at full load.
B
Require low hull contact pressures.
B
Single class of vessels using dedicated facilities.
B
Manifolds not necessarily at midships position.
SHIP FEATURES
Bow fl ares
Common on container vessels and cruise ships. Big fl are angles may affect fender performance. Larger fender may be required to maintain clearance from the quay structure, cranes, etc.
Bulbous bows
Most modern ships have bulbous bows. Care is needed at large berthing angles or with widely spaced fenders to ensure the bulbous bow does not catch behind the fender or hit structural piles.
Beltings & strakes
Almost every class of ship could be fi tted with beltings or strakes. They are most common on RoRo ships or ferries, but may even appear on container ships or gas carriers. Tugs and offshore supply boats have very large beltings.
Flying bridge
Cruise and RoRo ships often have fl ying bridges. In locks, or when tides are large, care is needed to avoid the bridge sitting on top of the fender during a falling tide.
Low freeboard
Barges, small tankers and general cargo ships can have a small freeboard. Fenders should extend down so that vessels cannot catch underneath at low tides and when fully laden.
Stern & side doors
RoRo ships, car carriers and some navy vessels have large doors for vehicle access. These are often recessed and can snag fenders – especially in locks or when warping along the berth.
High freeboard
Ships with high freeboard include ferries, cruise and container ships, as well as many lightly loaded vessels. Strong winds can cause sudden, large increases in berthing speeds.
Low hull pressure
Many modern ships, but especially tankers and gas carriers, require very low hull contact pressures, which are achieved using large fender panels or fl oating fenders.
Aluminium hulls
High speed catamarans and monohulls are often built from aluminium. They can only accept loads from fenders at special positions: usually reinforced beltings set very low or many metres above the waterline.
Special features
Many ships are modifi ed during their lifetime with little regard to the effect these changes may have on berthing or fenders. Protrusions can snag fenders but risks are reduced by large bevels and chamfers on the frontal panels.
BERTHING MODES
Side berthing
V
ϕ
α
Typical values 0° ≤ α ≤ 15° 100mm/s ≤ V ≤ 300mm/s 60° ≤ ϕ ≤ 90°Dolphin berthing
ϕ
α
TugV
Typical values 0° ≤ α ≤ 10° 100mm/s ≤ V ≤ 200mm/s 30° ≤ ϕ ≤ 90°End berthing
α
V
ϕ
Typical values 0° ≤ α ≤ 10° 200mm/s ≤ V ≤ 500mm/s 0° ≤ ϕ ≤ 10°Lock entrances
V
ϕ
α
Typical values 0° ≤ α ≤ 30° 300mm/s ≤ V ≤ 2000mm/s 0° ≤ ϕ ≤ 30° Ship-to-ship berthingϕ
V
α
Typical values 0° ≤ α ≤ 15° 150mm/s ≤ V ≤ 500mm/s 60° ≤ ϕ ≤ 90°BERTHING ENERGY
The kinetic energy of a berthing ship needs to be absorbed by a suitable fender system and this is most commonly carried out using well recognised deterministic methods as outlined in the following sections.
Normal Berthing Energy (E
N)
Most berthings will have energy less than or equal to the normal berthing energy (EN). The calculation should take into
account worst combinations of vessel displacement, velocity, angle as well as the various coeffi cients. Allowance should also be made for how often the berth is used, any tidal restrictions, experience of the operators, berth type, wind and current exposure.
The normal energy to be absorbed by the fender can be calculated as:
Where,
EN = Normal berthing energy to be absorbed by the fender (kNm)
M = Mass of the vessel (displacement in tonne) at chosen confi dence level.* VB = Approach velocity component perpendicular to the berthing line† (m/s).
CM = Added mass coeffi cient
CE = Eccentricity coeffi cient
CC = Berth confi guration coeffi cient
CS = Softness coeffi cient
* PIANC suggests 50% or 75% confi dence limits (M50 or M75) are appropriate to most cases. † Berthing velocity (V
B) is usually based on displacement at 50% confi dence limit (M50).
Abnormal Berthing Energy (E
A)
Abnormal impacts arise when the normal energy is exceeded. Causes may include human error, malfunctions, exceptional weather conditions or a combination of these factors.
The abnormal energy to be absorbed by the fender can be calculated as:
Where,
EA = Abnormal berthing energy to be absorbed by the fender (kNm)
FS = Safety factor for abnormal berthings
Choosing a suitable safety factor (FS) will depend on many factors:
The consequences a fender failure may have on berth operations.
B
How frequently the berth is used.
B
Very low design berthing speeds which might easily be exceeded.
B
Vulnerability to damage of the supporting structure.
B
Range of vessel sizes and types using the berth.
B
Hazardous or valuable cargoes including people.
B
PIANC Factors of Safety (F
S)
Vessel type Size FS
Tanker, bulk, cargo Largest Smallest 1.25 1.75 Container Largest Smallest 1.5 2.0 General cargo 1.75 RoRo, ferries ≥ 2.0 Tugs, workboats, etc 2.0
EN = 0.5 × M × V
B2 × CM × CE × CC × CSEA = FS × EN
Source: PIANC 2002; Table 4.2.5. PIANC recommends that ‘the factor of abnormal impact when derived should be not be less than 1.1 nor more than 2.0 unless exception circumstances prevail’. Source: PIANC 2002; Section 4.2.8.5.
SHIP DEFINITIONS
Many different defi nitions are used to describe ship sizes and classes. Some of the more common descriptions are given below.
USING SHIP TABLES
Ship tables originally appeared in PIANC 2002. They are divided into Confi dence Limits (CL) which are defi ned as the proportion of ships of the same DWT with dimensions equal to or less than those in the table. PIANC considers 50% to 75% confi dence limits are the most appropriate for design.
Please ask Trelleborg Marine Systems for supplementary tables of latest and largest vessel types including Container, RoRo, Cruise and LNG. LWT MD DWT
+
=
D DL MD = LWT + DWTThe ship tables show laden draft (DL) of vessels. The draft of a partly loaded ship (D) can be estimated using the
formula below: 50% 75% MD DL × LWT MD DL × (MD – DWT) D ≈ =
Vessel Type Length × Beam × Draft DWT Comments Small feeder 200m × 23m × 9m 1st Generation container
<1,000 teu
Feeder 215m × 30m × 10m 2nd Generation container 1,000–2,500 teu Panamax1 290m × 32.3m × 12m 3rd Generation container
2,500–5,000 teu Post-Panamax 305m × >32.3m × 13m 4th Generation container
5,000–8,000 teu Super post-Panamax (VLCS) 5th Generation container
>8,000 teu
Suezmax2 500m × 70m × 21.3m All vessel types in Suez Canal
Seaway-Max3 233.5m × 24.0m × 9.1m All vessel types in St Lawrence Seaway
Handysize 10,000–40,000 dwt Bulk carrier
Cape Size 130,000–200,000 dwt Bulk carrier Very large bulk carrier (VLBC) >200,000 dwt Bulk carrier Very large crude carrier (VLCC) 200,000–300,000 dwt Oil tanker Ultra large crude carrier (ULCC) >300,000 dwt Oil tanker
1. Panama Canal 2. Suez Canal 3. St Lawrence Seaway Lock chambers are 305m long and
33.5m wide. The largest depth of the canal is 12.5–13.7m. The canal is about 86km long and passage takes eight hours.
The canal, connecting the Mediterranean and Red Sea, is about 163km long and varies from 80–135m wide. It has no lock chambers but most of the canal has a single traffi c lane with passing bays.
The seaway system allows ships to pass from the Atlantic Ocean to the Great Lakes via six short canals totalling 110km, with 19 locks, each 233m long, 24.4m wide and 9.1m deep.
SHIP TABLES
Type DWT/GRT Displacement M50 LOA LBP B FL DL Wind area Lateral Front Full Load Ballast Full Load BallastGeneral cargo ship 1000 1580 63 58 10.3 1.6 3.6 227 292 59 88 2000 3040 78 72 12.4 1.9 4.5 348 463 94 134 3000 4460 88 82 13.9 2.1 5.1 447 605 123 172 5000 7210 104 96 16.0 2.3 6.1 612 849 173 236 7000 9900 115 107 17.6 2.5 6.8 754 1060 216 290 10000 13900 128 120 19.5 2.7 7.6 940 1340 274 361 15000 20300 146 136 21.8 3.0 8.7 1210 1760 359 463 20000 26600 159 149 23.6 3.1 9.6 1440 2130 435 552 30000 39000 181 170 26.4 3.5 10.9 1850 2780 569 709 40000 51100 197 186 28.6 3.7 12.0 2210 3370 690 846 Bulk carrier 5000 6740 106 98 15.0 2.3 6.1 615 850 205 231 7000 9270 116 108 16.6 2.6 6.7 710 1010 232 271 10000 13000 129 120 18.5 2.9 7.5 830 1230 264 320 15000 19100 145 135 21.0 3.3 8.4 980 1520 307 387 20000 25000 157 148 23.0 3.6 9.2 1110 1770 341 443 30000 36700 176 167 26.1 4.1 10.3 1320 2190 397 536 50000 59600 204 194 32.3 4.8 12.0 1640 2870 479 682 70000 81900 224 215 32.3 5.3 13.3 1890 3440 542 798 100000 115000 248 239 37.9 5.9 14.8 2200 4150 619 940 150000 168000 279 270 43.0 6.6 16.7 2610 5140 719 1140 200000 221000 303 294 47.0 7.2 18.2 2950 5990 800 1310 250000 273000 322 314 50.4 7.8 19.4 3240 6740 868 1450 Container ship 7000 10200 116 108 19.6 2.4 6.9 1320 1360 300 396 10000 14300 134 125 21.6 3.0 7.7 1690 1700 373 477 15000 21100 157 147 24.1 3.9 8.7 2250 2190 478 591 20000 27800 176 165 26.1 4.6 9.5 2750 2620 569 687 25000 34300 192 180 27.7 5.2 10.2 3220 3010 652 770 30000 40800 206 194 29.1 5.8 10.7 3660 3370 729 850 40000 53700 231 218 32.3 6.8 11.7 4480 4040 870 990 50000 66500 252 238 32.3 7.7 12.5 5230 4640 990 1110 60000 79100 271 256 35.2 8.5 13.2 5950 5200 1110 1220 Oil tanker 1000 1450 59 54 9.7 0.5 3.8 170 266 78 80 2000 2810 73 68 12.1 0.7 4.7 251 401 108 117 3000 4140 83 77 13.7 1.0 5.3 315 509 131 146 5000 6740 97 91 16.0 1.4 6.1 419 689 167 194 7000 9300 108 102 17.8 1.7 6.7 505 841 196 233 10000 13100 121 114 19.9 2.0 7.5 617 1040 232 284 15000 19200 138 130 22.5 2.6 8.4 770 1320 281 355 20000 25300 151 143 24.6 3.1 9.1 910 1560 322 416 30000 37300 171 163 27.9 3.7 10.3 1140 1990 390 520 50000 60800 201 192 32.3 4.9 11.9 1510 2690 497 689 70000 83900 224 214 36.3 5.7 13.2 1830 3280 583 829 100000 118000 250 240 40.6 6.8 14.6 2230 4050 690 1010 150000 174000 284 273 46.0 8.3 16.4 2800 5150 840 1260 200000 229000 311 300 50.3 9.4 17.9 3290 6110 960 1480 300000 337000 354 342 57.0 11.4 20.1 4120 7770 1160 1850 smaller larger
SHIP TABLES
Type DWT/GRT Displacement M50 LOA LBP B FL DL Wind area Lateral Front Full Load Ballast Full Load BallastRoRo ship 1000 1970 66 60 13.2 2.0 3.2 700 810 216 217 2000 3730 85 78 15.6 2.9 4.1 970 1110 292 301 3000 5430 99 90 17.2 3.6 4.8 1170 1340 348 364 5000 8710 119 109 19.5 4.7 5.8 1480 1690 435 464 7000 11900 135 123 21.2 5.5 6.6 1730 1970 503 544 10000 16500 153 141 23.1 6.7 7.5 2040 2320 587 643 15000 24000 178 163 25.6 8.2 8.7 2460 2790 701 779 20000 31300 198 182 27.4 9.5 9.7 2810 3180 794 890 30000 45600 229 211 30.3 11.7 11.3 3400 3820 950 1080 Passenger (cruise) ship 1000 850 60 54 11.4 2.2 1.9 426 452 167 175 2000 1580 76 68 13.6 2.8 2.5 683 717 225 234 3000 2270 87 78 15.1 3.2 3.0 900 940 267 277 5000 3580 104 92 17.1 3.9 3.6 1270 1320 332 344 7000 4830 117 103 18.6 4.5 4.1 1600 1650 383 396 10000 6640 133 116 20.4 5.0 4.8 2040 2090 446 459 15000 9530 153 132 22.5 5.9 5.6 2690 2740 530 545 20000 12300 169 146 24.2 5.2 7.6 3270 3320 599 614 30000 17700 194 166 26.8 7.3 7.6 4310 4350 712 728 50000 27900 231 197 30.5 10.6 7.6 6090 6120 880 900 70000 37600 260 220 33.1 13.1 7.6 7660 7660 1020 1040 Ferry 1000 810 59 54 12.7 1.9 2.7 387 404 141 145 2000 1600 76 69 15.1 2.5 3.3 617 646 196 203 3000 2390 88 80 16.7 2.8 3.7 811 851 237 247 5000 3940 106 97 19.0 3.3 4.3 1150 1200 302 316 7000 5480 119 110 20.6 3.7 4.8 1440 1510 354 372 10000 7770 135 125 22.6 4.2 5.3 1830 1930 419 442 15000 11600 157 145 25.0 4.7 6.0 2400 2540 508 537 20000 15300 174 162 26.8 5.2 6.5 2920 3090 582 618 30000 22800 201 188 29.7 5.9 7.4 3830 4070 705 752 40000 30300 223 209 31.9 6.5 8.0 4660 4940 810 860 Gas carrier 1000 2210 68 63 11.1 1.0 4.3 350 436 121 139 2000 4080 84 78 13.7 1.6 5.2 535 662 177 203 3000 5830 95 89 15.4 2.0 5.8 686 846 222 254 5000 9100 112 104 17.9 2.7 6.7 940 1150 295 335 7000 12300 124 116 19.8 3.2 7.4 1150 1410 355 403 10000 16900 138 130 22.0 3.8 8.2 1430 1750 432 490 15000 24100 157 147 24.8 4.6 9.3 1840 2240 541 612 20000 31100 171 161 27.1 5.4 10.0 2190 2660 634 716 30000 44400 194 183 30.5 6.1 11.7 2810 3400 794 894 50000 69700 227 216 35.5 9.6 11.7 3850 4630 1050 1180 70000 94000 252 240 39.3 12.3 11.7 4730 5670 1270 1420 100000 128000 282 268 43.7 15.6 11.7 5880 7030 1550 1730 smaller larger
SHIP TABLES
Type DWT/GRT Displacement M75 LOA LBP B FL DL Wind area Lateral Front Full Load Ballast Full Load BallastGeneral cargo ship 1000 1690 67 62 10.8 1.9 3.9 278 342 63 93 2000 3250 83 77 13.1 2.3 4.9 426 541 101 142 3000 4750 95 88 14.7 2.5 5.6 547 708 132 182 5000 7690 111 104 16.9 2.8 6.6 750 993 185 249 7000 10600 123 115 18.6 3.0 7.4 922 1240 232 307 10000 14800 137 129 20.5 3.3 8.3 1150 1570 294 382 15000 21600 156 147 23.0 3.6 9.5 1480 2060 385 490 20000 28400 170 161 24.9 3.9 10.4 1760 2490 466 585 30000 41600 193 183 27.8 4.3 11.9 2260 3250 611 750 40000 54500 211 200 30.2 4.6 13.0 2700 3940 740 895 Bulk carrier 5000 6920 109 101 15.5 2.4 6.2 689 910 221 245 7000 9520 120 111 17.2 2.6 6.9 795 1090 250 287 10000 13300 132 124 19.2 2.9 7.7 930 1320 286 340 15000 19600 149 140 21.8 3.3 8.6 1100 1630 332 411 20000 25700 161 152 23.8 3.6 9.4 1240 1900 369 470 30000 37700 181 172 27.0 4.1 10.6 1480 2360 428 569 50000 61100 209 200 32.3 4.7 12.4 1830 3090 518 723 70000 84000 231 221 32.3 5.2 13.7 2110 3690 586 846 100000 118000 255 246 39.2 5.9 15.2 2460 4460 669 1000 150000 173000 287 278 44.5 6.7 17.1 2920 5520 777 1210 200000 227000 311 303 48.7 7.3 18.6 3300 6430 864 1380 250000 280000 332 324 52.2 7.8 19.9 3630 7240 938 1540 Container ship 7000 10700 123 115 20.3 2.6 7.2 1460 1590 330 444 10000 15100 141 132 22.4 3.3 8.0 1880 1990 410 535 15000 22200 166 156 25.0 4.3 9.0 2490 2560 524 663 20000 29200 186 175 27.1 5.0 9.9 3050 3070 625 771 25000 36100 203 191 28.8 5.7 10.6 3570 3520 716 870 30000 43000 218 205 30.2 6.4 11.1 4060 3950 800 950 40000 56500 244 231 32.3 7.4 12.2 4970 4730 950 1110 50000 69900 266 252 32.3 8.4 13.0 5810 5430 1090 1250 60000 83200 286 271 36.5 9.2 13.8 6610 6090 1220 1370 Oil tanker 1000 1580 61 58 10.2 0.5 4.0 190 280 86 85 2000 3070 76 72 12.6 0.8 4.9 280 422 119 125 3000 4520 87 82 14.3 1.1 5.5 351 536 144 156 5000 7360 102 97 16.8 1.5 6.4 467 726 184 207 7000 10200 114 108 18.6 1.8 7.1 564 885 216 249 10000 14300 127 121 20.8 2.1 7.9 688 1090 255 303 15000 21000 144 138 23.6 2.7 8.9 860 1390 309 378 20000 27700 158 151 25.8 3.2 9.6 1010 1650 355 443 30000 40800 180 173 29.2 3.9 10.9 1270 2090 430 554 50000 66400 211 204 32.3 5.0 12.6 1690 2830 548 734 70000 91600 235 227 38.0 6.0 13.9 2040 3460 642 884 100000 129000 263 254 42.5 7.1 15.4 2490 4270 761 1080 150000 190000 298 290 48.1 8.5 17.4 3120 5430 920 1340 200000 250000 327 318 42.6 9.8 18.9 3670 6430 1060 1570 300000 368000 371 363 59.7 11.9 21.2 4600 8180 1280 1970 smaller larger
SHIP TABLES
Type DWT/GRT Displacement M75 LOA LBP B FL DL Wind area Lateral Front Full Load Ballast Full Load BallastRoRo ship 1000 2190 73 66 14.0 2.7 3.5 880 970 232 232 2000 4150 94 86 16.6 3.9 4.5 1210 1320 314 323 3000 6030 109 99 18.3 4.7 5.3 1460 1590 374 391 5000 9670 131 120 20.7 6.1 6.4 1850 2010 467 497 7000 13200 148 136 22.5 7.3 7.2 2170 2350 541 583 10000 18300 169 155 24.6 8.8 8.2 2560 2760 632 690 15000 26700 196 180 27.2 10.7 9.6 3090 3320 754 836 20000 34800 218 201 29.1 12.4 10.7 3530 3780 854 960 30000 50600 252 233 32.2 15.2 12.4 4260 4550 1020 1160 Passenger (cruise) ship 1000 1030 64 60 12.1 2.3 2.6 464 486 187 197 2000 1910 81 75 14.4 2.9 3.4 744 770 251 263 3000 2740 93 86 16.0 3.4 4.0 980 1010 298 311 5000 4320 112 102 18.2 4.2 4.8 1390 1420 371 386 7000 5830 125 114 19.8 4.7 5.5 1740 1780 428 444 10000 8010 142 128 21.6 5.3 6.4 2220 2250 498 516 15000 11500 163 146 23.9 6.2 7.5 2930 2950 592 611 20000 14900 180 160 25.7 7.3 8.0 3560 3570 669 690 30000 21300 207 183 28.4 9.8 8.0 4690 4680 795 818 50000 33600 248 217 32.3 13.7 8.0 6640 6580 990 1010 70000 45300 278 243 35.2 16.6 8.0 8350 8230 1140 1170 Ferry 1000 1230 67 61 14.3 2.1 3.4 411 428 154 158 2000 2430 86 78 17.0 2.6 4.2 656 685 214 221 3000 3620 99 91 18.8 2.9 4.8 862 903 259 269 5000 5970 119 110 21.4 3.5 5.5 1220 1280 330 344 7000 8310 134 124 23.2 3.9 6.1 1530 1600 387 405 10000 11800 153 142 25.4 4.3 6.8 1940 2040 458 482 15000 17500 177 164 28.1 5.0 7.6 2550 2690 555 586 20000 23300 196 183 30.2 5.5 8.3 3100 3270 636 673 30000 34600 227 212 33.4 6.2 9.4 4070 4310 771 819 40000 45900 252 236 35.9 6.9 10.2 4950 5240 880 940 Gas carrier 1000 2480 71 66 11.7 1.1 4.6 390 465 133 150 2000 4560 88 82 14.3 1.5 5.7 597 707 195 219 3000 6530 100 93 16.1 2.0 6.4 765 903 244 273 5000 10200 117 109 18.8 2.6 7.4 1050 1230 323 361 7000 13800 129 121 20.8 3.2 8.1 1290 1510 389 434 10000 18900 144 136 23.1 3.9 9.0 1600 1870 474 527 15000 27000 164 154 26.0 4.8 10.1 2050 2390 593 658 20000 34800 179 169 28.4 5.5 11.0 2450 2840 696 770 30000 49700 203 192 32.0 6.7 12.3 3140 3630 870 961 50000 78000 237 226 37.2 10.5 12.3 4290 4940 1150 1270 70000 105000 263 251 41.2 13.4 12.3 5270 6050 1390 1530 100000 144000 294 281 45.8 16.9 12.3 6560 7510 1690 1860 smaller larger
USE WITH CAUTION Deadweight (DWT)* 1,000 e 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Approach velocity , V B (m/ s) 500,000 100,000 10,000 d c b a most commonly used conditions
Berthing speeds depend on the ease or diffi culty of the approach, the exposure of the berth and the vessel’s size. Conditions are normally divided into fi ve categories as shown in the chart’s key table.
The most widely used guide to approach speeds is the Brolsma table, adopted by BS1, PIANC2 and other standards.
For ease of use, speeds for the main vessel sizes are shown at the bottom of this page.
Berthing condition a Easy berthing, sheltered b Diffi cult berthing, sheltered c Easy berthing, exposed d Good berthing, exposed e Diffi cult berthing, exposed
Velocity, VB (m/s) DWT a b c d e 1,000 0.179 0.343 0.517 0.669 0.865 2,000 0.151 0.296 0.445 0.577 0.726 3,000 0.136 0.269 0.404 0.524 0.649 4,000 0.125 0.250 0.374 0.487 0.597 5,000 0.117 0.236 0.352 0.459 0.558 10,000 0.094 0.192 0.287 0.377 0.448 20,000 0.074 0.153 0.228 0.303 0.355 30,000 0.064 0.133 0.198 0.264 0.308 40,000 0.057 0.119 0.178 0.239 0.279 50,000 0.052 0.110 0.164 0.221 0.258 100,000 0.039 0.083 0.126 0.171 0.201 200,000 0.028 0.062 0.095 0.131 0.158 300,000 0.022 0.052 0.080 0.111 0.137 400,000 0.019 0.045 0.071 0.099 0.124 500,000 0.017 0.041 0.064 0.090 0.115 Caution: low berthing speeds are easily exceeded.
Approach velocities less than
B
0.1m/s should be used with caution.
Values are for tug-assisted
B
berthing.
Spreadsheets for calculating the
B
approach velocity and berthing energy are available at www.trelleborg.com/marine . Actual berthing velocities can be
B
measured, displayed and recorded using a SmartDock Docking Aid System (DAS) by Harbour Marine.† † Harbour Marine is part of
Trelleborg Marine Systems.
APPROACH VELOCITY (V
B
)
V
BThe added mass coeffi cient allows for the body of water carried along with the ship as it moves sideways through the water. As the ship is stopped by the fender, the entrained water continues to push against the ship, effectively increasing its overall mass. The Vasco Costa method is adopted by most design codes for ship-to-shore berthing where water depths are not substantially greater than vessel drafts.
The block coeffi cient (CB) is a function of the hull shape and is expressed as follows:
where,
MD = displacement of vessel (t)
LBP = length between perpendiculars (m)
B = beam (m) D = draft (m)
ρSW = seawater density ≈ 1.025t/m3
Typical block coeffi cients (C
B)
Container vessels 0.6–0.8 General cargo and bulk carriers 0.72–0.85
Tankers 0.85 Ferries 0.55–0.65 RoRo vessels 0.7–0.8 D B LBP B D Quay KC
V
BADDED MASS COEFFICIENT (C
M
)
BLOCK COEFFICIENT (C
B
)
PIANC (2002) Shigera Ueda (1981) Vasco Costa* (1964) for ≤ 0.1 D KC CM = 1.8 2 × CB × B π × D = CM B 2D = 1 + CM for ≤ 0.5 D KC 0.1 ≤ CM = 1.875 – 0.75 D KC for ≥ 0.5 D KC CM = 1.5 where, D = draft of vessel (m) B = beam of vessel (m) LBP = length between perpendiculars (m) KC = under keel clearance (m)
Special case – longitudinal approach
V
CM = 1.1Recommended by PIANC. Given ship dimensions and using typical block coeffi cients,
the displacement can be estimated:
MD ≈ CB × LBP × B × D × ρSW * valid where VB ≥ 0.08m/s, KC ≥ 0.1D
L
BP× B × D ×
ρSW
M
D=
C
BR ϕ α LBP x y V VL VB B 2 berthing line
Common berthing cases
Quarter-point berthing CE ≈ 0.4–0.6 Third-point berthing CE ≈ 0.6–0.8 Midships berthing CE ≈ 1.0 x = 4 LBP x = 3 LBP x = 2 LBP
Where the ship has a signifi cant forward motion, PIANC suggests that the ship’s speed parallel to the berthing face (Vcosα) is not decreased by berthing impacts, and it is the transverse velocity component (Vsinα) which much be resisted by the fenders. When calculating the eccentricity coefficient, the velocity vector angle (ϕ) is taken between V and R.
Ships rarely berth exactly midway between dolphins. ROM 0.2-90 suggests a=0.1L, with a minimum of 10m and maximum of 15m between the midpoint and the vessel’s centre of mass. This offset reduces the vector angle (ϕ) and increases the eccentricity coeffi cient.
V
R
ϕ
α
α
ϕ
TugV
R
aECCENTRICITY COEFFICIENT (C
E
)
The Eccentricity Coeffi cient allows for the energy dissipated by rotation of the ship about its point of impact with the fenders. The correct point of impact, berthing angle and velocity vector angle are all important for accurate calculation of the eccentricity coeffi cient.
In practice, CE often varies
between 0.3 and 1.0 for different berthing cases.
Velocity (V) is not always perpendicular to the berthing line. VL = longitudinal velocity component (forward or astern)
x + y = 2 LBP 2 2 B y2 R= + K = (0.19 × CB + 0.11) × LBP where, B = beam (m) CB = block coeffi cient
LBP = length between perpendiculars (m)
R = centre of mass to point of impact (m) K = radius of gyration (m)
Caution: for
ϕ < 10º, C
EJ 1.0
(assuming the centre of mass is at mid-length of the ship)
K
2+ R
2K
2+ R
2cos
2ϕ
=
C
EBreasting dolphins Approach A B C
α
≤ 15ºϕ
V
1R
V
2V
3 ≤0.25LS ≤0.25LS ≤0.25LS ≤0.25LS ≤0.25LSEnd fender and shore based ramp
R
Outer end
Inner end
α
End fender and shore based ramp
V
3V
2 ≤0.25LS ≥ 1.05LL Breasting dolphinsV
1α
≤ 15º A B Cϕ
Modern RoRo terminals commonly use two different approach modes during berthing. PIANC defi nes these as mode b) and mode c). It is important to decide whether one or both approach modes will be used, as the berthing energies which must be absorbed by the fenders can differ considerably.
Mode b)
Mode c)
RoRo vessels with bow and/or stern ramps make a transverse approach to the berth. The ships then move along the quay or dolphins using the side fenders for guidance until they are the required distance from the shore ramp structure.
Lower berthing energy
B
Reduced speeds may affect ship manoeuvrability
B
Increased turn-around time
B
C
B E is smaller (typically 0.4–0.7)
RoRo vessels approach either head-on or stern-on with a large longitudinal velocity. Side fenders guide the vessel but ships berth directly against the shore ramp structure or dedicated end fenders.
Quicker berthing and more controllable in strong winds
B
High berthing energies
B
Risk of vessel hitting inside of fenders or even the
B
dolphins C
B E can be large (typically 0.6–0.9)
ECCENTRICITY COEFFICIENT (C
E
)
Special cases for RoRo Terminals
Fender Typical values
A Side 100mm/s ≤ V1 ≤ 300mm/s 60° ≤ ϕ ≤ 90°
B Side 300mm/s ≤ V2 ≤ 500mm/s N/A
C End 200mm/s ≤ V3 ≤ 500mm/s 0° ≤ ϕ ≤ 10°
Fender Typical values
A Side 1000mm/s ≤ V1 ≤ 3000mm/s 0° ≤ ϕ ≤ 50°
B Side 500mm/s ≤ V2 ≤ 1000mm/s 0° ≤ ϕ ≤ 50°
When ships berth at small angles against solid structures, the water between hull and quay acts as a cushion and dissipates a small part of the berthing energy. The extent to which this factor contributes will depend upon several factors:
SOFTNESS COEFFICIENT (C
S
)
Where fenders are hard relative to the fl exibility of the ship hull, some of the berthing energy is absorbed by elastic deformation of the hull. In most cases this contribution is limited and ignored (CS=1). PIANC recommends the following
values:
BERTH CONFIGURATION COEFFICIENT (C
C
)
CC = 1.0
Open structures including berth corners
B
Berthing angles > 5º
B
Very low berthing velocities
B
Large underkeel clearance
B
CC = 0.9
Solid quay structures
B
Berthing angles > 5º
B
Closed structure
Semi-closed structure
Quay structure design
B
Underkeel clearance
B
Velocity and angle of approach
B
Projection of fender
B
Vessel hull shape
B
PIANC recommends the following values:
CS = 1.0 Soft fenders (δf > 150mm)
CS = 0.9 Hard fenders (δf ≤ 150mm)
Note: where the under keel clearance has already been considered for added mass (CM), the berth confi guration
FENDER SELECTION
Comparing effi ciency
Every type and size of fender has different performance characteristics. Whatever type of fenders are used, they must have suffi cient capacity to absorb the normal and abnormal energies of berthing ships.When selecting fenders the designer must consider many factors including:
Single or multiple fender contacts
B
The effects of angular compressions
B Approach speeds B Extremes of temperature B Berthing frequency B
Fender effi ciency
B
Reaction
Deflection
ENERGY
= area under curve
Fender effi ciency is defi ned as the ratio of the energy absorbed to the reaction force generated. This method allows fenders of many sizes and types to be compared as the example shows.
Comparisons should also be made at other compression angles, speeds and temperatures when applicable.
R
D
E
R
D
E
Super Cone
SCN 1050 (E2)
E = 458kNm R = 843kN D = 768mm P = 187kN/m2 *SeaGuard
SG 2000 × 3500 (STD)
E = 454kNm R = 845kN D = 1200mm P = 172kN/m2E
= 0.543 kNm/kN
R
E
= 0.537 kNm/kN
R
* for a 4.5m2 panel This comparison shows SuperCone and SeaGuard fenders with similar energy, reaction and hull pressure, but different height, defl ection and initial stiffness (curve gradient).
FENDER PITCH
Fenders spaced too far apart may allow ships to hit the structure. A positive clearance (C) should always be maintained, usually between 5–15% of the uncompressed fender height (H).
A minimum clearance of 300mm inclusive of bow fl are is commonly specifi ed.
Smaller ships have smaller bow
B
radius but usually cause smaller fender defl ection.
Clearance distances should take
B
account of bow fl are angles. Bow fl ares are greater near to
B
the bow and stern. Where ship drawings are
B
available, these should be used to estimate bow radius.
δF
α
θ θ θ P h h = H – δF Bow radius, R B H C P 2 / P/2Bow radius
where, RB = bow radius (m) B = beam of vessel (m) LOA = vessel length overall (m)Fender pitch
where,
P = pitch of fender RB = bow radius (m)
h = fender projection when compressed, measured at centreline of fender a = berthing angle
C = clearance between vessel and dock (C should be 5–15% of the undefl ected fender projection, including panel)
θ = hull contact angle with fender
As a guide to suitable distance between fenders on a continuous wharf, the formula below indicates the maximum fender pitch. Small, intermediate and large vessels should be checked.
According to BS 6349: Part 4: 1994, it is also recommended that the fender spacing does not exceed 0.15 × LS, where LS is the length of the smallest ship.
Caution
Large fender spacings
may work in theory but
in practice a maximum
spacing of 12–15m is more
realistic.
0 0 65 0 140 0 425Displacement (1000 t) Displacement (1000 t) Displacement (1000 t)
Bow radius (metres)
50 100 150 200
Cruise liner Container ship Bulk carrier/
general cargo
RB
≈
+
8B
L
OA2
2
1
2
B
P ≤ 2 R
B 2– (R
B– h + C)
2The bow radius formula is
approximate and should be checked against actual ship dimensions where possible.
MULTIPLE CONTACT CASES
Flare
Bow radius
Dolphin
β θ α P Bow radius, R B α
where RB = bow radius
2RB
P = sinθ Energy absorbed by three (or more) fenders
B
Larger fender defl ection likely
B
Bow fl are is important
B
1-fender contact also possible for ships with small
B
bow radius
Energy divided over 2 (or more) fenders
B
Smaller fender defl ections
B
Greater total reaction into structure
B
Clearance depends on bow radius and bow fl are
B
3-fender contact
2-fender contact
ANGULAR BERTHING
The berthing angle between the fender and the ship’s hull may result in some loss of energy absorption. Angular berthing means the horizontal and/or vertical angle between the ship’s hull and the berthing structure at the point of contact. There are three possible conditions for the effects of angular berthing: fl are, bow radius and dolphin.
P P H Berthing line Berthing line Berthing line Berthing line P RB RB P P
δ
Fδ
F2δ
F2δ
F1 RB RB P 2 / P/2FENDER PANEL DESIGN
Fender panels are used to distribute reaction forces into the hulls of berthing vessels. The panel design should consider many factors including:
Hull pressures and tidal range
B
Lead-in bevels and chamfers
B
Bending moment and shear
B
Local buckling
B
Limit state load factors
B
Steel grade
B
Permissible stresses
B
Weld sizes and types
B
Effects of fatigue and cyclic
B
loads
Pressure test method
B
Rubber fender connections
B UHMW-PE attachment B Chain connections B Lifting points B Paint systems B Corrosion allowance B
Maintenance and service life
B
3 design cases
Full-face contact
Low-level impact
Double contact
F F R R R1 R2 n × T F1 F2
The national standards of France and Germany have been replaced by EN 10025. In the UK, BS4360 has been replaced by BS EN 10025. The table above is for guidance only and is not comprehensive. Actual specifi cations should be consulted in all cases for the full specifi cations of steel grades listed and other similar grades.
PIANC steel thicknesses
PIANC recommends the following minimum steel thicknesses for fender panel construction:
Exposed both faces ≥ 12mm Exposed one face ≥ 9mm Internal (not exposed) ≥ 8mm
Corresponding minimum panel thickness will be 140–160mm (excluding UHMW-PE face pads) and often much greater.
Typical panel weights
The table can be used as a guide to minimum average panel weight (excluding UHMW-PE face pads) for different service conditions:
Light duty 200–250kg/m2 Medium duty 250–300kg/m2 Heavy duty 300–400kg/m2 Extreme duty ≥400kg/m2
Steel Properties
Standard Grade Yield Strength (min) Tensile Strength (min) Temperature N/mm² psi N/mm² psi °C °F EN 10025 S235JR (1.0038) 235 34 000 360 52 000 – – S275JR (1.0044) 275 40 000 420 61 000 – – S355J2 (1.0570) 355 51 000 510 74 000 -20 -4 S355J0 (1.0553) 355 51 000 510 74 000 0 32 JIS G-3101 SS41 235 34 000 402 58 000 0 32 SS50 275 40 000 402 58 000 0 32 SM50 314 46 000 490 71 000 0 32 ASTM A-36 250 36 000 400 58 000 0 32 A-572 345 50 000 450 65 000 0 32
HULL PRESSURES
Allowable hull pressures depend on hull plate thickness and frame spacing. These vary according to the type of ship. PIANC gives the following advice on hull pressures:
Vessel type Size/class Hull pressure (kN/m2) Container ships < 1 000 teu (1st/2nd generation) < 3 000 teu (3rd generation) < 8 000 teu (4th generation) > 8 000 teu (5th/6th generation) < 400 < 300 < 250 < 200 General cargo ≤ 20 000 DWT > 20 000 DWT 400–700 < 400 Oil tankers ≤ 20 000 DWT ≤ 60 000 DWT > 60 000 DWT < 250 < 300 150–200 Gas carriers LNG/LPG < 200 Bulk carriers < 200 RoRo Passenger/cruise SWATH
Usually fi tted with beltings (strakes) P = average hull pressure (kN/m2)
R = total fender reaction (kN) W = panel width, excluding bevels (m) H = panel height, excluding bevels (m)
W H W × H R P =
BELTINGS
Most ships have beltings (sometimes called belts or strakes). These come in many shapes and sizes – some are well-designed, others can be poorly maintained or modifi ed.
Care is needed when designing fender panels to cope with beltings and prevent snagging or catching which may damage the system.
Belting line loads exert crushing forces on the fender panel which must be considered in the structural design.
Belting range is often greater than tidal range due to ship design, heave, roll, and changes in draft. Application Vessels Belting Load (kN/m) Light duty Aluminium hulls 150–300 Medium duty Container 500–1 000 Heavy duty RoRo/Cruise 1 000–1 500
Belting types
≥ h h 3 1 2 3Common on RoRo/Cruise ships. Projection 200–400mm (typical).
Common on LNG/Oil tankers, barges, offshore supply vessels and some container ships. Projection 100–250mm (typical).
1 2 Belting
range
FRICTION
SWL =
n cos
θ
μR + W
Friction has a large infl uence on the fender design, particularly for restraint chains. Low friction facing materials (UHMW-PE) are often used to reduce friction. Other materials, like polyurethanes (PU) used for the skin of foam fenders, have lower friction coeffi cients than rubber against steel or concrete.
The table can be used as a guide to typical design values. Friction coeffi cients may vary due to wet or dry conditions, local temperatures, static and dynamic load cases, as well as surface roughness.
Materials Friction Coeffi cient (μ) UHMW-PE Steel 0.2 HD-PE Steel 0.3 Polyurethane Steel 0.4 Rubber Steel 0.7 Timber Steel 0.4 Steel Steel 0.5
CHAIN DESIGN
Chains can be used to restrain the movements of fenders during compression or to support static loads. Chains may serve four main functions:
Weight chains support the steel panel and prevent
B
excessive drooping of the system. They may also resist vertical shear forces caused by ship movements or changing draft.
Shear chains resist horizontal forces caused during
B
longitudinal approaches or warping operations. Tension chains restrict tension on the fender rubber.
B
Correct location can optimise the defl ection geometry. Keep chains are used to moor fl oating fenders or to
B
prevent loss of fi xed fenders in the event of accidents.
Factors to be considered when designing fender chains:
Corrosion reduces link diameter and weakens the chain.
B
Corrosion allowances and periodic replacement should
B
be allowed for.
A ‘weak link’ in the chain system is desirable to prevent
B
damage to more costly components in an accident.
3 Tension chains Weight chains Shear chains 1 2 3 1 θ μR W where,
SWL = safe working load (kN) FC = safety factor
μ = coeffi cient of friction R = fender reaction (kN) W = gross panel weight (kg) (for shear chains, W = 0) n = number of chains
θ = effective chain angle (degrees)
2
Typical friction design values
UHMW-PE FACING
Always use oversize washers
to spread the load.
The contact face of a fender panel helps to determine the lifetime maintenance costs of a fender installation. UHMW-PE (FQ1000) is the best material available for such applications. It uniquely combines low friction, impact strength, non-marking characteristics and resistance to wear, temperature extremes, seawater and marine borers.
Sinter moulded into plates at extremely high pressure, UHMW-PE is a totally homogeneous material which is available in many sizes and thicknesses. These plates can be cut, machined and drilled to suit any type of panel or shield.
Fastening example
Large pads vs small pads
Larger pads are usually more robust but smaller pads are easier and cheaper to replace. Application t (mm) W* (mm) Bolt Light duty 30 3–5 M16 Medium duty 40 7–10 M16–M20 50 10–15 Heavy duty 60 15–19 M24–M30 70 18–25 80 22–32 Extreme duty 90 25–36 M30–M36 100 28–40 t W
* Where allowances are typical values, actual wear allowance may vary due fi xing detail. The standard colour is black, but
UHMW-PE is available in many other colours if required.
CORROSION PREVENTION
Fenders are usually installed in corrosive environments, sometimes made worse by high temperature and humidity. Corrosion of fender accessories can be reduced with specialist paint coatings, by galvanising or with selective use of stainless steels.
Paint coatings and galvanising have a fi nite life. Coating must be reapplied at intervals during the life of the fender. Galvanised components like chains or bolts may need periodic re-galvanising or replacement. Stainless steels should be carefully selected for their performance in seawater.
ISO EN 12944 is a widely used international standard defi ning the durability of corrosion protection systems in various environments. The C5-M class applies to marine coastal, offshore and high salinity locations and is considered to be the most applicable to fenders.
The life expectancy or ‘durability’ of coatings is divided into three categories which estimate the time to fi rst major maintenance:
Paint coatings
Low 2–5 years Medium 5–15 years High >15 years
Durability range is not a guarantee. It is to help operators estimate sensible maintenance times.
Paint System
Surface Preparation
Priming Coat(s) Top Coats Paint System Expected durability (C5-M corrosivity) Binder Primer No. coats NDFT Binder No. coats NDFT No. coats NDFT
S7.09 Sa 2.5 EP, PUR Zn (R) 1 40 EP, PUR 3-4 280 4-5 320 High (>15y) S7.11 Sa 2.5 EP, PUR Zn (R) 1 40 CTE 3 360 4 400 High (>15y) S7.16 Sa 2.5 CTE Misc 1 100 CTE 2 200 3 300 Medium (5-15y) Sa 2.5 is defi ned in ISO 8501-1
NDFT = Nominal dry fi lm thickness Zn (R) = Zinc rich primer
Misc = miscellaneous types of anticorrosive pigments EP = 2-pack epoxy
PUR = 1-pack or 2-pack polyurethane CTE = 2-pack coal tar epoxy
Design considerations
Other paint systems may also satisfy the C5-M requirements but in choosing any coating the designer should carefully consider the following:
Corrosion protection systems are not a substitute for poor design details such as re-entrant shapes and corrosion traps.
B
Minimum dry fi lm thickness >80% of NDFT (typical)
B
Maximum fi lm thickness <3 × NDFT (typical)
B
Local legislation on emission of solvents or health & safety factors
B
Application temperatures, drying and handling times
B
Maximum over-coating times
B
Local conditions including humidity or contaminants
B
Refer to paint manufacturer for advice on specifi c applications and products.
The table gives some typical C5-M class paint systems which provide high durability in marine environments. Note that coal tar epoxy paints are not available in some countries.
CORROSION PREVENTION
Galvanising
Hot-dip galvanising is the process of coating steel parts with a zinc layer by passing the component through a bath of molten zinc. When exposed to sea water the zinc acts as an anodic reservoir which protects the steel underneath. Once the zinc is depleted the steel will begin to corrode and lose strength.
Galvanising thickness can be increased by:
shot blasting the components before dipping
B
pickling the components in acid
B
double dipping the components (only suitable for some steel
B
grades)
Spin galvanising is used for threaded components which are immersed in molten zinc then immediately centrifuged to remove any excess zinc and clear the threads. Spin galvanised coatings are thinner than hot dip galvanised coatings and will not last as long in marine environments.
Typical galvanising thicknesses:
Hot dip galvanising 85μm Spin galvanising 40μm
Stainless steels
Percentages of Cr, Mo and N are typical mid-range values and may differ within permissible limits for each grade. Source: British Stainless Steel Association (www.bssa.org.uk).
Grade Common
Name Type Cr (%) Mo (%) N (%) PREN Comments
1.4501 Zeron 100 Duplex 24.0–26.0 3.0– 4.0 0.2–0.3 37.1–44.0 used where very long service life is needed or access for inspection is diffi cult 1.4462 SAF 2205 Duplex 21.0–23.0 2.5–3.5 0.1–0.22 30.9–38.1
1.4401 316S31 Austenitic 16.5–18.5 2.0–2.5 0–0.11 23.1–28.5 widely used for fender fi xings 1.4301 304 Austenitic 17.0–19.5 – 0–0.11 17.0–21.3
unsuitable for most fender applications 1.4003 3CR12 Ferritic 10.5–12.5 – 0–0.03 10.5–13.0
Pitting Resistance
Stainless steel performance in seawater varies according to pitting resistance. Chemical composition – especially Chromium (Cr), Molybdenum (Mo) and Nitrogen (N) content – is a major factor in pitting resistance.
The pitting resistance equivalent number (PREN) is a theoretical way to compare stainless steel grades. The most common formula for PREN is:
PREN = Cr + 3.3Mo + 16N
Cr and Mo are major cost factors for stainless steel. A high PREN material will usually last longer but cost more.
Galling
Galling or ‘cold welding’ affects threaded stainless steel components including nuts, bolts and anchors. The protective oxide layer of the stainless steel gets scraped off during tightening causing high local friction and welding of the threads. After galling, seized fasteners cannot be further tightened or removed and usually needs to be cut out and replaced.
To avoid this problem, always apply anti-galling compounds to threads before assembly. If these are unavailable then molybdenum disulfi de or PTFE based lubricants can be used.
PROJECT REQUIREMENTS
PROJECT DETAILS Port Project Designer Contractor PROJECT STATUS TMS Ref: Preliminary Detail design Tender LARGEST VESSEL Vessel type Deadweight (t) Displacement (t) Length overall (LOA) (m)Length between perps (LBP) (m)
Beam (B) (m) Draft (D) (m) Freeboard (F) (m) Hull pressure (P) (t/m2) SMALLEST VESSEL Vessel type Deadweight (t) Displacement (t) Length overall (LOA) (m)
Length between perps (LBP) (m)
Beam (B) (m)
Draft (D) (m)
Freeboard (F) (m)
Hull pressure (P) (t/m2)
BERTH DETAILS
Structure Tide levels
Length of berth (m) Tidal range (m)
Fender/dolphin spacing (m) Highest astronomic tide (HAT) (m) Permitted fender reaction (kN/m) Mean high water spring (MHWS) (m)
Quay level (m) Mean sea level (MSL) (m)
Cope thickness (m) Mean low water spring (MLWS) (m)
Seabed level (m) Lowest astronomic tide (LAT) (m)
LBP
LOA B
D F
PROJECT REQUIREMENTS
BERTHING MODE
Side berthing
Dolphin berthing incl. RoRo mode b)
End berthing
Lock or dock entrance
Ship-to-ship berthing
RoRo mode c)
BERTHING APPROACH
Approach conditions
a) easy berthing, sheltered b) diffi cult berthing, sheltered c) easy berthing, exposed d) good berthing, exposed e) diffi cult berthing, exposed
Largest ship
Berthing speed (m/s)
Berthing angle (deg)
Abnormal impact factor
Smallest ship
Berthing speed (m/s)
Berthing angle (deg)
Abnormal impact factor
ENVIRONMENT
Operating temperature
Minimum ___________________________________ (°C) Maximum __________________________________ (°C)
Corrosivity
low medium high extreme
FURTHER DETAILS AVAILABLE FROM
Name Tel Company Fax Position Mobile Address Email Web QUALITY SAFETY
Highest quality Maximum safety
RUBBER PROPERTIES
All Trelleborg rubber fenders are made using the highest quality Natural Rubber (NR) or Styrene Butadiene Rubber (SBR) based compounds which meet or exceed the performance requirements of international fender recommendations, such as PIANC and EAU. Trelleborg can also make fenders from other NR/SBR compounds or from materials such as Neoprene, Butyl Rubber, EPDM and Polyurethane.
Different manufacturing processes such as moulding, wrapping and extrusion require certain characteristics from the rubber. The tables below give usual physical properties for fenders made by these processes which are confi rmed during quality assurance testing.* All test results are from laboratory made and cured test pieces. Results from samples taken from actual fenders will differ due to the sample preparation process – please ask for details.
Moulded fenders
Property Testing Standard Condition Requirement
Tensile Strength DIN 53504; ASTM D 412 Die C; AS 1180.2; BS ISO 37; JIS K 6251
Original 16.0 MPa (min)
Aged for 96 hours at 70ºC 12.8 MPa (min) Elongation at Break DIN 53504; ASTM D 412 Die C; AS 1180.2;
BS ISO 37; JIS K 6251
Original 350%
Aged for 96 hours at 70ºC 280% Hardness DIN 53505; ASTM D 2240;
AS1683.15.2; JIS K 6253
Original 78° Shore A (max)
Aged for 96 hours at 70ºC Original +8° Shore A (max) Compression Set ASTM D 395 Method B; AS 1683.13 Method B; BS903 A6; ISO 815; JIS K 6262 22 hours at 70°C 30% (max)
Tear Resistance ASTM D 624 Die B; AS 1683.12;
BS ISO 34-1; JIS K 6252 Original 70kN/m (min)
Ozone Resistance DIN 53509; ASTM D 1149; AS 1683-24; BS ISO 1431-1; JIS K 6259 50pphm at 20% strain,40°C, 100 hours No cracks
Seawater Resistance BS ISO 1817; ASTM D 471 28 days at 95°C Hardness: ±10° Shore A (max)Volume: +10/-5% (max)
Abrasion ASTM D5963-04; BS ISO 4649 : 2002 Original 100mm3 (max)
BS903 A9, Method B 3000 revolutions 1.5cc (max)
Bond Strength ASTM D429, Method B; BS 903.A21 Section 21.1 Rubber to steel 7N/mm (min)
Dynamic Fatigue† ASTM D430-95, Method B 15,000 cycles Grade 0–1‡
Property Testing Standard Condition Requirement
Tensile Strength DIN 53504; ASTM D 412 Die C; AS 1180.2; BS ISO 37; JIS K 6251
Original 13.0 MPa (min)
Aged for 96 hours at 70ºC 10.4 MPa (min) Elongation at Break DIN 53504; ASTM D 412 Die C; AS 1180.2;
BS ISO 37; JIS K 6251
Original 280% (min)
Aged for 96 hours at 70ºC 224% (min) Hardness DIN 53505; ASTM D 2240;
AS1683.15.2; JIS K 6253
Original 78° Shore A (max)
Aged for 96 hours at 70ºC Original +8° Shore A (max) Compression Set ASTM D 395 Method B; AS 1683.13 Method B; BS903 A6; ISO 815; JIS K 6262 22 hours at 70°C 30% (max)
Tear Resistance ASTM D 624 Die B; AS1683.12;
BS ISO 34-1; JIS K 6252 Original 60kN/m (min)
Ozone Resistance DIN 53509; ASTM D 1149; AS 1683-24; BS ISO 1431-1; JIS K 6259 50pphm at 20% strain,40°C, 100 hours No cracks
Seawater Resistance BS ISO 1817; ASTM D 471 28 days at 95°C Hardness: ±10° Shore A (max)Volume: +10/-5% (max)
Abrasion ASTM D5963-04; BS ISO 4649 : 2002 Original 180mm3 (max)
Extruded and wrapped fenders
* Material property certifi cates are issued for each different rubber grade on all orders for SCN Super Cone, SCK Cell Fender, Unit Element, AN/ANP Arch, Cylindrical Fender, MV and MI Elements. Unless otherwise requested at time of order, material certifi cates issued for other fender types are based on results of standard bulk and/or batch tests which form part of routine factory ISO9001 quality procedures and are for a limited range of physical properties (tensile strength, elongation at break and hardness).
† Dynamic fatigue testing is optional at extra cost.