MO4 - Setting New Offshore Standards’ Post

The Right Ship for the Right Location Selecting the right ship for offshore operations is crucial, yet the current evaluation methods often fall short. Most ships in offshore tenders are assessed based on significant wave height (Hs), with engineering studies assuming waves, wind, and current all come from the same direction. In reality, this is never the case, leading to two possible scenarios: 1. Over-dimensioning the ship, resulting in excessive costs. 2. Under-dimensioning the ship, leading to poor performance. While this conflict may seem complex, there is a straightforward solution. The vessel’s performance can be quantified as an operability percentage per month. By simulating offshore operations over decades for a specific location, we can assess the vessel’s potential. These results should be cross-verified with measurements from similar vessels in equivalent locations to ensure accuracy. This comprehensive approach includes integrating factors like wind, sea, swell, directional spreading, and currents. At MO4, we utilise measured ship data to verify that your vessel’s potential is accurately presented. Our clear and easy-to-understand workability tables, as shown in the picture below, ensure that your vessel is optimally suited for its intended location.

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We looked at this issue and presented to RINA Offshore Wind Conference over 10 years ago. The question is what do you mean by "operability", and how do you define maximum wave height? What aspect of the vessel are you using to define operability limits in each case? We recognised that it's not the vessel that matters, it's the technicians who are being transferred to the turbines (in the case of CTVs). If technicians are compelled to endure an hour of high accelerations, they will not be any fit state to work. So, operability limits move to motion sickness incidence, rather than any specific vessel response. We then related that back to an example far-shore windfarm, held motion sickness as the foundation for operability, then varied the vessel size and arrived at optimum size and number of vessels for a particular wind farm. The experience of many operators is now so deep that this effect is probably intrinsic in how they respond to charter calls. For larger vessels in the C/SOV arena, the actual operational requirement needs to be properly defined in order to use "operability" in a valid way (in our case all those years ago, it was transfer of willing OTs).

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