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Introduction
Published in Srinivasan Chandrasekaran, Offshore Semi-Submersible Platform Engineering, 2020
Mooring configuration should be symmetric to the platform’s major axis to avoid rotational motion under wave action. Anchoring is different from a mooring. While the former refers to the operation of holding an object about a fixed point, the latter refers to connecting the moving object to the fixed point, rigidly. Anchoring commonly refers to the holding of any object, but mooring refers to connecting a floating body. In the case of slack-mooring, the length of the mooring is about three times more than the water depth. Anchor points of the mooring should not be widely spread as it may affect the free-access of service vessels to the offshore platform. Simultaneously, the layout of a spread mooring is too close and will not counteract the lateral loads caused by waves (Gottlieb and Yim, 1992). Therefore, the mooring layout plays an essential role in the response behavior of the complaint platform. A mooring system comprises mooring lines, anchors, connectors, clump weights, and other accessories required for anchoring the mooring line to the permanent anchor in the seabed. In some instances, large floating buoys, which are permanently anchored to the seabed, can also be used as temporary moorings. Figure 1.24 shows the anatomy of a Turret-mooring system.
Offshore Structure and Design
Published in Shashi Shekhar Prasad Singh, Jatin R. Agarwal, Nag Mani, Offshore Operations and Engineering, 2019
Shashi Shekhar Prasad Singh, Jatin R. Agarwal, Nag Mani
Ships or vessels at sea have to be kept in their place to enable oil or gas production, transfer, and storage on board. Mooring is a system of permanent or temporary station keeping at sea. A vessel is said to be moored when it is fastened or held secured to a fixed object such as a pier or quay or to a floating object such as an anchor buoy using cables, anchors, or lines. Mooring and anchors are very critical for the stability of a floating system (Figure 2.17).
Seaweed in high-energy environments
Published in Bénédicte Charrier, Thomas Wichard, C.R.K. Reddy, Protocols for Macroalgae Research, 2018
Biological issues Observe the length increment of the plant during the grow-out. At the beginning of the cultivation process, seeding density and early growth should be determined. In the further grow-out weekly/two-weekly visits are sufficient during normal weather conditions.In the case of prolonging severe conditions or storm events, a site visit after that is of prime importance as seaweed detachment or complete loss could occur.Technical issuesThe system design and the entire farm equipment also need a detailed inspection at any time during the visits to prevent failures or the damage/loss of equipment.Moorings (still at the same place?), connecting pieces (shackles, thimbles, swivels, rings, etc., are ok and service loads not exceeded?), backbones or other ropes, and chains of the harness (no unraveled or entangled parts?), and the complete buoyancy (too deep, fully submerged, loss?) need to be scrutinized.The system has to be controlled for fouling organisms settling potentially on all hard substrates of the harness. If the fouling increases a certain biomass, the entire system will experience too much stress because of the increase in volume and the resulting surface. Due to the increasing surface the drag coefficient will change resulting into higher loads.As already mentioned earlier, after prolonging severe conditions, a farm visit is mandatory.
Scientific rationale and conceptual design of a process-oriented shelfbreak observatory: the OOI Pioneer Array
Published in Journal of Operational Oceanography, 2020
Glen Gawarkiewicz, Albert J. Plueddemann
Moorings are necessary to provide time series of important variables at multiple locations across and along the front. The moored array is centred at the shelfbreak roughly 130 km south of Martha’s Vineyard (Figure 1), a region with relatively straight bathymetry distant from complicating features such as canyons and river outflows. The moored array consists of two lines running north–south (Figure 5): one along 70° 53’ W (western line) and one along 70° 46.5’ W (upstream line). The moored array incorporates ten moorings at seven sites – three sites contain a mooring pair (Table 2). The mooring sites are named according to their relative position within the array and referred to by two-letter codes. Locations (Table 2) designate the site centre. Each site has an operating radius of 1 km (Figure 5); all moorings are deployed within the operating radius, typically within 500 m of the centre. Moorings are deployed for approximately 6 months and then recovered for refurbishment; refurbished moorings are deployed at the same site to maintain a continuous time series.