Design Parameters for Increased Operability of Offshore Crane Vessels

Abstract

Marine subsea operations are performed by highly specialized ships, referred to as Inspection, Maintenance, and Repair (IMR) and Offshore Construction Vessels (OCV). Although the ships and their on-board equipment are designed to operate in harsh environmental conditions, the current practice often is to terminate operations when a rigid and conservative weather limitation is reached, often specified in terms of the significant wave height as the exclusive criterion. Such general limitations do not account for vessel specific motion behavior. Since the offshore industry is aiming for all-year-round safe subsea operations, there is a strong interest amongst ship designers, owners and operators to establish vessel and task specific criteria. The project Vessel Performance within the Norwegian Centre for Research-based Innovation on Marine Operations (SFI MOVE), is developing response-based procedures, that are leading to case-specific operational ranges. This approach enables the full exploitation of vessel performance capabilities for safe and efficient offshore operations. Two methods with different complexity levels are proposed. Firstly, on the higher level, detailed operability analysis for a fleet and sea area of interest are performed by means of numerical tools. This level can be used to obtain detailed results for existing ships, but the procedure can also be applied as guidance in the design stage. Secondly, on the lower level, generic diagrams can be used to estimate and compare the operational performance of different vessels based on fact sheet parameters. This is especially relevant for decision making processes where a detailed study cannot be performed.

Operability analysis of traditional small fishing boats in Indonesia with different loading conditions

“…Recently, some researchers developed a new operability index showing a single seakeeping criterion, such as RMS roll. Gutsch et al (2017) introduced the new performance indicator, namely the Integrated Operability Factor (IOF), defined as the ratio of the area below the curve of percentage operability for a single criterion from zero to its maximum limitation (OP tot max ) and the area of the maximum possible operability (100% × OP tot max ). In this case, the OP tot max of RMS Roll criterion was determined according to STANAG (Eriksen et al 2000) for replenishment operations at sea, which is 2.2°.…”

“…In this case, the OP tot max of RMS Roll criterion was determined according to STANAG (Eriksen et al 2000) for replenishment operations at sea, which is 2.2°. The work of Gutsch et al (2017) investigated the change of some main dimensions of Offshore Construction Vessels (OCV), such as length, breadth, draught, transversal GM, and radius of gyration of roll (R 44 ) to the IOF value of RMS Roll. Sandvik et al (2018) used IOF for every single criterion of the RMS of heave, pitch, roll, and vertical crane displacement for the OCV.…”

A simulation-based ship design methodology for evaluating susceptibility to weather-induced delays during marine operations

“…For quantification of response-based operability of offshore vessels, the integrated operability factor (IOF) was introduced as a parameter for seakeeping performance in parametric studies (Gutsch et al (2016) and Gutsch et al (2017)). This measure assesses the steepness of the operability-limit curve, as illustrated in Figure 9.…”

“…The presented simulation-based methodology represents an alternative to the percentage operability and integrated operability factor (IOF) (see Gutsch et al (2016Gutsch et al ( , 2017), which are established methods for assessing vessel susceptibility for weather delays and seakeeping performance during marine operations. To address this, we state the following research questions:…”

Effective utilization of service vessels in fish farming: fleet design considering the characteristics of the locations

“…That is, how waves can build up before reaching the farm. Left-hand map is retrieved from the Norwegian Directorate of Fisheries ( 2021a) is studied for other maritime industries, including percent operability based on scatter analysis (Gutsch et al, 2016;Tezdogan et al, 2014), the relative rate of operation based on discrete-event simulation (Sandvik et al, 2018), and the operability robustness index (Gutsch et al, 2020). For other segments, such as traditional shipping, the literature also covers long-term operational performance of fleets of vessels in the context of strategic problems such as the maritime fleet size and mix problem (Álvarez et al, 2011;Pantuso et al, 2014;Sperstad et al, 2017), and short-term maritime fleet routing and scheduling (Álvarez, 2009;Lianes et al, 2021;Psaraftis, 2019).…”