With the preparation and development of the updated fender guidelines by PIANC WG211, it is evident that clear and uniform design recommendations for vessel berthing velocities need to be derived, since this is one of the most critical parameters in fender-system design. This paper outlines recommendations on how to ascertain characteristic berthing velocities for fender-system design, both in situations with and without the availability of site-specific information. The new PIANC WG211 fender design guideline advocates using sitespecific information, knowledge and experience where available (for example, utilising berthing records, past service performance, vessel approach speed limits, or the input of pilots and harbour masters) when defining the characteristic berthing velocities. Acknowledging that site-specific information is not always readily available, the PIANC WG211 report also provides recommendations for berthing velocities that can be considered in such circumstances. Furthermore, this paper explains the rationale behind the proposed berthing velocity table, which will serve as a valuable resource in fender-system design when site-specific information is lacking. The recommended characteristic berthing velocities in this study are carefully derived, taking into consideration the berthing velocities recommended in various design guidelines, including PIANC WG33, PIANC WG145, the German EAU2020, BS6349, the Spanish ROM, Japanese OCDI, Indian Standard IS4651, American UFC and MOTEMS. Additionally, this paper incorporates insights from recently published and unpublished berthing velocity records from the United States, Northeast Europe and Korea. The comprehensive examination of available information prompted a reassessment of some historically embedded hypotheses within the fender industry. The key findings resulting from this study significantly contribute to the design and assessment of fender systems. In essence, this paper underlines the crucial role of site-specific information and experience in determining characteristic berthing velocities. Practical recommendations are provided for scenarios where such information is unavailable, emphasising the importance of monitoring and adopting site-specific velocities as effective measures to optimise fender designs.. This approach aims to bridge the gap between theoretical considerations and practical applications in the maritime engineering domain, offering valuable insights for engineers and practitioners involved in fender-system design and assessment.@en

PIANC WG211 was tasked with updating the guidelines for design of marine fender systems. One of the changes to the new guideline is the change in approach to the design. Whilst the load and resistance factor design approach is widely adopted in the design of marine structures, the PIANC WG33 (2002) design guideline utilises a global safety factor, referred to as the factor for ‘abnormal’ impact. Based on statistical data from recorded berthing velocities, fender manufacturers’ data, and adjustment factors for uncertainties in berthing energy calculation, PIANC WG211 has established partial factors of safety for fender selection. To gain clarity on what the effects the updated design approach is, this paper compares the outcomes of the old PIANC WG33 and the new PIANC WG211 guideline. Data from actual project fender design specifications have been considered. Given similar input variables the new design method generally results in marginally smaller fender dimensions. WG211, however, recommends, on the basis of PIANC WG145 (2019), higher berthing velocities for large seagoing vessels compared to Brolsma’s berthing velocity curves in PIANC WG33, which can result in quite large fenders in the absence of site-specific information. During this study, however, the higher berthing velocities recommended by PIANC WG211 were confirmed based on new berthing records collected in a port in the northeast part of Europe. In general, when site-specific information is used to evaluate the navigation conditions and the associated berthing velocity, the design method of PIANC WG211 will result in reasonable fender dimensions. In addition, it was found that the fender dimensions can, in some cases, largely be optimised based on a parametric analysis of the fender pitch. Consequently, the conclusion is that the new design approach results in reasonable fender dimensions for majority of the ports and terminals around the world. Nevertheless, it is crucial to examine the influence of the local navigation conditions, such as wind, wave, currents and berthing manoeuvres, on the berthing velocity and that the asset owner, e.g. port or terminal authority, specifies the required safety level of the fender system specific to the berth.
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Design of fender systems consists of two distinct steps: selection of an appropriate fender based on berthing energy demands from the berthing vessel and design of the supporting structure based on the reaction force imposed by the fender on the structure. Both steps include load or safety factors to increase the level of safety. The factor applied to the selection of fenders has up until now been referred to as an "abnormal berthing factor," with relatively vague recommendations for suggested values for use, usually between 1.25 and 2.0. British Standards (BS 6349-4:2014) has recently chosen to refer to this value as an "energy factor" instead of the previously used abnormal berthing factor. Codes and standards for design of most structures are often based on methods involving what is often referred to as load factors, partial load factors, or resistance factors. As an example, Load and Resistance Factor Design (LRFD) in the US applies load factors to the different loads acting on a structure, and resistance factors to the capacities provided by the structural elements. Similarly, the Eurocode, OCDI, and British Standards use the partial factor method where the effect of the characteristic action, which can be a specified load or imposed deflection, multiplied by the load factor must not exceed the design resistance, i.e., characteristic resistance divided by the partial factors for materials. Although their applications are seemingly simple, these methodologies are based on substantial statistical work, including extensive collection of statistical data, a careful analysis of the data, and appropriate selections of safety levels and acceptable probabilities of failure. This paper explores how utilizing statistical data from berthing velocities, fender manufacturer data, and other adjustment factors were used to establish suggested partial energy factors for selection of fenders. This is what previously has been described as the abnormal berthing factor. By utilizing this method, energy factors can be recommended based on several factors, such as anticipated vessel traffic, type of terminal, type of fender system, or whether the analysis is done for new or existing structures. The suggested factors will provide much clearer guidance than what is currently given in the current fender design guidelines from PIANC WG33 and will be the basis for recommendations on energy factors in the upcoming document from WG211.

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