What is a Yokohama Fender?

Yokohama fenders are floating air-filled pneumatic rubber marine fenders, not a proprietary single product. Their energy absorption relies on dimension, length and internal air pressure instead of the trade name. They are manufactured and tested to ISO 17357-1:2014, covering ≥50 kPa high-pressure types with two standard grades: P50 (50 kPa) and P80 (80 kPa). Misusing the "Yokohama" label directly leads to wrong product selection; original Yokohama Rubber Company is the originator, while many homonymous spellings refer to the identical product.

Sealed compressed air absorbs impact force, consisting of an air-sealing inner rubber layer, load-bearing reinforced cord layers, wear-resistant outer skin and sealed end flanges. Fenders ≥2500 mm diameter must be equipped with safety valves for over-compression pressure relief.

• Merit: Conforms to ship hull surfaces under oblique contact (stable energy absorption within 15° inclined compression), distributes contact stress to lower hull pressure and reaction force greatly, ideal for ship-to-ship (STS) operations. Solid rubber fenders degrade obviously under angled collision.
• Hidden defect: Sealed air pressure fluctuates with ambient temperature. Pressure measurement must adopt manufacturer-specified temperature correction methods to avoid abnormal pressure judgment caused by sunlight or temperature changes.

• Net type: Protected by chain/fiber nets plus anti-abrasion rubber sleeves, designed for long-term fixed installation with severe abrasion.
• Sling type: Equipped with end lifting lugs connected by tension chains/ropes, lighter weight for frequent moving, recovery and redeployment. Key inspection focus for tidal docks: tension chains and flange shackles bearing cyclic water-level displacement.

1st confirmed factor: initial contact approach velocity (berthing energy is proportional to the square of velocity, far more influential than vessel displacement which has linear correlation with energy) + allowable berth reaction force + vessel hull pressure limit.

2nd: Confirm fender diameter/length according to calculated berthing energy.

Last: Select net/sling installation style.

Under identical dimensions, P80 delivers higher energy absorption capacity yet generates larger reaction force and hull pressure, which can only be adopted within the bearing capacity of dock structures and ship hulls. Design references: ISO 17357-1:2014 (product manufacturing & testing standard) + PIANC 2024 Fender Guidelines (system design code). Important reminder: PIANC never issues product certification, so "PIANC-certified fenders" are false claims.

Copying pressure grades from old similar vessel projects without recalculating actual berthing data will cause excessive reaction force damaging dock structures. Solutions include adjusting pressure grade, size, quantity, layout or limiting ship berthing speed.

The 2014 standard has been updated and validated in 2024; it regulates material, performance, dimensional tolerance and test protocols. Mandatory delivery checks:

1. Legible ISO 17357-1:2014 marking, serial number, actual size & pressure grade consistent with purchase order
2. Valid prototype & factory test certificates (air pressure, hydrostatic test records)
3. Safety valve installation & calibrated pressure for fenders over 2500 mm diameter
4. Integrity inspection for flanges, valves, shackles and protective sling/net structures
5. Third-party survey reports if required by terminals or charterers

ISO certification only proves product qualification; matching practical berth/STS working conditions relies on independent engineering calculation.

Complete fender specification must clarify three core premises first: verified berthing approach velocity, maximum permissible dock reaction force and vessel hull pressure threshold. Simply specifying fender dimensions without these three indexes will inevitably result in mismatched fender systems and potential structural hazards.