
- Prediction of the ship response motion characteristics of the vessel. It is defined through the Response Amplitude Operators (RAO) of the vessel.
- Estimation of the likely sea environmental conditions to be encountered by the vessel. It is defined through the wave spectra of a chosen location.
- Specification of the limiting criteria used to assess the vessel’s seakeeping behaviour. This also defines the way in which the performance of different vessels is compared related to vessel’s mission.
Mission of a seastead
Vertical RMS acceleration (g)
|
Description
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0.020
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Passengers on a cruise liner. Older people. Close to the lower threshold below which vomiting is unlikely
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0.050
|
Passengers on a ferry. The international ISO-2631 standard for 2 h exposure period. Causes symptoms of motion sickness in approximately 10% of unacclimated adults
|
0.100
|
Intellectual work by people reasonably well adapted to ship motions (i.e. scientific personnel on ocean research vessels). Cognitive/manual work of a more demanding nature. Tolerable in the long term for the crew. The international standard for half an hour exposure period
|
0.15
|
Heavy manual labor by people adapted to ship motions, i.e. on fishing vessels and supply ships
|
0.200
|
Light manual labor by people adapted to ship motions. Not tolerable for longer periods. Quickly causes fatigue
|
0.275
|
Simple light work. Most of the attention must be devoted to keeping balance. Tolerable only for short periods on high-speed craft
|
When designing the Clubstead, the value for the limiting criteria for vertical acceleration was set to 0.020g (0,20 m/s2). This is the same comfort level as in any cruise vessel as shown in the previous table. Therefore, this value could be adequate criteria to assess the performance of any seastead.
- RAOs of the vessel/structure.
- Wave spectra of the ocean location.
Ref. 1: Couser, Patrick. Seakeeping analysis for preliminary design. Fremantle, Australia: Formation Design Systems, 2009.
Ref. 2: Sario¨z, Kadir; Narli, Ebru. Effect of criteria on seakeeping performance assessment. Faculty of Naval Architecture and Ocean Engineering, Istanbul Technical University. Ocean Engineering. February 2005.