floating marine fenders

Floating Pneumatic Rubber Fenders

Floating Pneumatic Rubber Fenders 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 .

Ship to ship operation of floating pneumatic fenders

Follow the flow chart which simply demonstrate the procedure of floating fenders selection .

floating fenders selection -revise

There is a quick reference  to do the floating fender selection tentatively as per the listed OCIMF Table . If the energy absorption of the tentative selected  pneumatic fender (Ef) is larger than the calculated berthing energy (E) . It means that a suitable floating pneumatic rubber fender selection has been made . If the Yokohama fenders energy absorption capacity is less than the calculated berthing energy . The selected yokohama fenders should be upgraded and selected again .

OCIMF Chart for floating pneumatic rubber fenders-revise

 

 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 .

floating fenders

Where :

E     = Berthing Energy ( in KNm or ton / m)

marine rubber fenders = Equivalent Displacement Coefficient

rubber narine fenders  = Relative Approaching Velocity

ship fenders = Eccentricity Factor

SF  = Safety Factor

marine rubber fenders

pneumatic rubber fenders

 

floating pneumatic fenders

pneumatic fenders

Where :

ship rubber fenders  = Water displacement of the berthing ship A ( tons )

rubber ship fenders  = Water displacement of the berthing ship B ( tons )

rubber marine fenders = Added mass coefficient of ship A

rubber pneumatic fenders = Added mass coefficient of ship B

Added Mass Coefficient

marine fenders  or

rubber fenders

Where :

d = Full load draft  (m , ft )

B = Molded Breadth (m , ft )

floating rubber fenders =  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 .

Eccentricity Factor

foam fenders

yokohama fenders

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

floating rubber fenders = Block coefficient

L = Length of ship

Relative Approaching

The berthing energy needs to be calculated considering weather conditions ,categorized by the three conditions calm,moderate and rough , and the approaching velocity to calculate the berthing energy are asumed to be as the follow table . These information are obtained from various industry references and standards .

floating pneumatic rubber fenders

Ship to Quay Operation of Floating Pneumatic Rubber Fenders

The selection and installation of pneumatic fenders (fendering) system for a quay is determined based on several design parameters for each ship berthing and mooring condition .

The energy can be calculated by the following formula :

rubber marine fender

 

Where :

E =  Berthing Energy ( in KNm or ton / m)

M = Displacement ( ton )

V =  Berthing Velocity ( m / s )

floating pneumatic marine fenders = Eccentricity Factor

foam marine fenders =  Vitural mas factor ,

rubber fenders

d = Full load draft (m,  ft )

B = Molded Breadth (m,  ft )

SF = Safety Factor

floating pneumatic rubber marine fenders = Berthing configuration factor

This is the portion of berthing energy which is absorbed by the cushion effect of water between the approaching vessel and the quay wall .The smaller the draft of the vessel is , or the large the under keel clearance , the more trapped water can escape under the vessel , and would give a higher floating pneumatic marine fenders Valve . Also , if the berthing angle of the vessel is greater than 5 degree , we can consider floating pneumatic rubber marine fenders = 1 .

pneumatic rubber marine fenders =  Softness coefficient

This is the portion of berthing energy which is absorbed by the deformation of the vessels’s hull and fender . When a soft fender is issued, pneumatic rubber marine fenders = 0.9

 

 

 

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