The determination of the elastic modulus of rubber mooring tethers and their use in coastal moorings

Irish, James D.; Paúl, Walter; Wyman, D.

doi:10.1575/1912/519

Cited by 4 publications

(3 citation statements)

References 13 publications

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“…wind generator and telemetry antennas and GPS on the mast on a calm day. These 12 m compliant elastic tethers supply about 350 Newton's force each at 100% stretch, and normally are prestretched 100% for an application, and yet can stretch several hundred percent if necessary without breaking [12]. Therefore, each of the two assemblies (of two elastic tethers each) has about 700 Newtons tension under normal load of mid-tide and no waves or currents.…”

Section: Mooring Configurationmentioning

confidence: 99%

Study of a Three Point Mooring of an Open Ocean Aquaculture Feed Buoy

et al. 2007

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Open ocean aquaculture will be important in supplying fish as natural fish stocks decline due to environmental changes and overfishing. However, the technology needs to be developed to provide the equipment and methodology for such offshore operations. The University of New Hampshire has been developing and testing systems in the open Gulf of Maine, and has a number of years experience with a feed buoy moored to a fish cage via a stretch hose and elastic tethers. This configuration has survived the Gulf of Maine currents and waves, and continued to feed fish autonomously. The unique tri-mooring is studied via modeling, and observing the wear and behavior for years. The system is robust and has functioned well over the years and is a good candidate for aquaculture operations. I. INTRODUCTION The University of New Hampshire (UNH) has been developing the technology for open ocean aquaculture over the last decade at a site offthe Coast of New Hampshire in 52 m of water in the open Gulf of Maine [1]. Several different size and types of fish containment cages have been deployed and evaluated at the site [2, 3, 4]. A major part of an aquaculture operation is feeding the fish with the goal of optimizing the amount, rate and timing of feeding events for fish growth. An open ocean aquaculture operation is quite different than sheltered operations due to the increased environmental forcing (currents and waves). To develop offshore feeding capability, a feed buoy was designed [5], constructed and moored to a submerged fish cage by a compliant stretch hose [6] and elastic tethers [7]. This tri-moor is necessary to allow the feed buoy to move with surface waves, yet decouple its motion from the fish cage that is nearly stationary at a depth of approximately 10 meters. Feed is stored in the buoy and pumped into the cage via the stretch hose, under control of the buoy computer system. A study of this coupled feed buoy, fish cage and mooring system is presented as a possible successful configuration for open ocean aquaculture operations.

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Section: Mooring Configurationmentioning

confidence: 99%

Study of a Three Point Mooring of an Open Ocean Aquaculture Feed Buoy

et al. 2007

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“…The modulus is the slope of stress-strain curve and is plotted in Fig. 6 for a summary [7]. It is clear that at the high elongation end of each cycle, the modulus rises sharply, and as he mean tension or The tensions in the top panel of Fig.…”

Section: B Compliant Elastics At the Bottom Of A Mooringmentioning

confidence: 98%

“…In order to model the elastic tether mooring configuration, the elastic modulus of the Natsyn material used in the tethers was measured for different mean elongations and cycles around each mean and the results fit to a function of elongation for input into WHOI Cable [7]. Model runs were then made and the results used to illustrate the differences between the chain catenary and compliant elastic tether mooring approach to supplying compliance.…”

Section: Introductionmentioning

confidence: 99%

On Compliance in Coastal Moorings

Irish

Proceedings of OCEANS 2005 MTS/IEEE

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To better understand mooring behavior in the coastal ocean, the WHOI Cable modeling program was used to examine several chain catenary and compliant elastic tether mooring configurations. The chain catenary is used most often, and is the most robust, although if many instruments are used in the mooring line and a depressor weight used to keep the mooring more vertical in high currents, the tensions in the mooring can easily exceed 15,000 lbs in heavy seas and currents. On the other hand, elastic tethers on moorings with few heavy instruments in the mooring line, can provide a lighter mooring with smaller, lower cost buoy and hardware that can still survive the severe conditions in the ocean environment. Tensions in these moorings rarely exceed 2,000 lbs. The high tensions in the chain catenary moorings are due to the heavy instrumentation that must be accelerated by the buoy as it follows the waves, and is generally too large for compliant elastic tether configurations.

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Optimal design of a single-point electromechanical cable subsurface mooring

Yin

2023

Ships and Offshore Structures

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The determination of the elastic modulus of rubber mooring tethers and their use in coastal moorings

Cited by 4 publications

References 13 publications

Study of a Three Point Mooring of an Open Ocean Aquaculture Feed Buoy

Study of a Three Point Mooring of an Open Ocean Aquaculture Feed Buoy

On Compliance in Coastal Moorings

Optimal design of a single-point electromechanical cable subsurface mooring

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