Chain Net Yokohama Fender , Ship To Boat Fender Rubber With Tyres
Floating yokohama fender is a fender which is made of
synthetic-cord-reinforced rubber sheet with compressed air inside
to enable it to float on the water and work as the absorber between
ship to ship , ship to berthing structure when they come alongside
each other on the water . The design and selection of floating
fenders can be confirmed as per the maximum energy absorption of
specific conditions .we should calculate and compare the
requirements for the energy of the following condition; The Kinetic
energy when the ship berthing or after berthing; the energy of
relative motion of ship to ship and ship to wharf .
Fender structure
Outer Rubber
The tough abrasion resistant outer rubber is designed to protect
the inner rubber and tyre-cord layers from damaging external
forces. The material has mechanical properties to withstand the
arduous operational conditions for which it is designed.
The diagram below shows the actual properties as specified in ISO
17357. Generally, the outer rubber is black, but other colours such
as grey and off-white can be supplied upon request.
Tyre-cord Layer
Synthetic tyre-cord layers have proven to be the best option for
strong, efficient reinforcement for pneumatic rubber fenders. Each
layer is coated with a rubber compound on both sides that prevents
contact between the layers, reducing friction and
wear during bending, compression and stretching. The same compound
isolates each thread within the layer.
This greatly improves the ability of the fender to hold pressure,
fatigue resistance and endurance life. Other reinforcing layer
materials such as canvas have wear points that significantly reduce
the life off the fender.
Inner Rubber
The inner rubber seals pressurised air inside the fender. It is
usually constructed of a compound similar to that of an inner tube
in a truck or car tyre to ensure a good level of air tightness.
OCIMF Table Selection of YOKOHAMA fenders
It is a quick reference selection based on 50 Kpa ( Pneumatic 50 )
and calm condition , Equivalent Displacement coefficient (C) should
be calculated firstly , then make the tentatively selection as per
OCIMF ship to ship transfer guide .
C= 2 x Displacement ShipA x Displacement ShipB / ( Displacement
ShipA + Displacement ShipB )
Berthing Energy Calculation of pneumatic rubber fenders
The berthing energy can be calculated by the following formula .
Where :
E = Berthing Energy ( in KNm or ton / m)
= Equivalent Displacement Coefficient
= Relative Approaching Velocity
= Eccentricity Factor
SF = Safety Factor
Where :
= Water displacement of the berthing ship A ( tons )
= Water displacement of the berthing ship B ( tons )
= Added mass coefficient of ship A
= Added mass coefficient of ship B
Added Mass Coefficient
or
Where :
d = Full load draft (m , ft )
B = Molded Breadth (m , ft )
= Block coefficient
Safety Factor
A safety factor (SF) value from 1.0 to 2.0 for the berthing energy
shall be considered for abnormal berthing conditions .
Where :
I = Radius of rotation of the vessel ( usually 1/4 of the vessel’s
length )
r = Distance of the line paralleled to wharf measured from the
vessel’s center of gravity to the point of contact
a = the angle degree
= Block coefficient
L = Length of ship
Relative Approaching
How to choose the right size fender
A船舶(DWT) A vessel(DWT) | B船舶(DWT) B vessel(DWT) | 假定接舷速度(m/s) ASSumed speed Access side(m/s) | 有效运动能量(kJ) Effectirve kinetic energy
| 护舷尺寸(D*L) Fender Dimension (D*L) |
| 300,000 | 200,000 | 0.15 | 1230 | 3.3*6.5 |
| 150,000 | 0.15 | 1030 | 3.3*6.5 |
| 100,000 | 0.15 | 781 | 3.3*6.5 |
| 200,000 | 150,000 | 0.15 | 882 | 3.3*6.5 |
| 100,000 | 0.15 | 693 | 3.3*6.0 |
| 85,000 | 0.15 | 618 | 3.0*5.0 |
| 100,000 | 85,000 | 0.17 | 617 | 3.0*5.0 |
| 50,000 | 0.18 | 511 | 3.0*5.0 |
| 40,000 | 0.20 | 544 | 3.0*5.0 |
| 50,000 | 40,000 | 0.20 | 425 | 2.5*5.5 |
| 30,000 | 0.22 | 437 | 2.5*5.5 |
| 20,000 | 0.25 | 443 | 2.5*5.5 |
| 20,000 | 15,000 | 0.27 | 318 | 2.5*4.0 |
| 10,000 | 0.30 | 309 | 2.2*3.5 |
| 5,000 | 0.35 | 253 | 2.0*3.5 |
| 10,000 | 5,000 | 0.35 | 212 | 2.0*3.5 |
| 3,000 | 0.40 | 196 | 2.0*3.5 |
| 1,000 | 0.50 | 137 | 2.0*3.0 |
