This paper describes the mechanical behaviour of ropes used for deep sea oceanographic operations. First the requirements of deep sea handling ropes are presented. Two high performance fibres are commonly used, aramid co-polymer and high modulus polyethylene (HMPE), and these are then compared. Results from tests on single fibres and 50 ton break load braided ropes are presented, which show that the initial stiffness of a new HMPE rope increases with load level in a bedding-in process resulting from both molecular alignment and construction reorientation. The aramid rope is less sensitive to this effect and shows a high stiffness from first loading. Measurements made at sea on oceanographic ropes of both materials using an elastic recoil method are presented, and apparent modulus values are consistent with laboratory measurements. Once both ropes have been fully bedded-in the HMPE is significantly stiffer, particularly under dynamic loads. Creep tests indicate that aramids creep less quickly than HMPE under constant loads over a 6 h period at 20 °C. Bending over sheave tests indicate longer lifetimes for the aramid but further tests on wet aramid are required to complete this conclusion.
Highlights► Original data on the mechanical behaviour of two types of deep sea handling rope. ► New results from measurements at sea. ► A discussion of the relative merits of aramid and HMPE fibre ropes for this application.
Temporal magmatic evolution of the Fani Maoré submarine eruption 50 km east of Mayotte revealed by in situ sampling and petrological monitoring Évolution magmatique temporelle de l'éruption sous-marine de Fani Maoré, située à 50 km à l'est de Mayotte, révélée par un échantillonnage in situ et un suivi pétrologique
27 PROGRAM NEWS the MD203 ACCLIMAtE expedition was the first coring cruise onboard the Research Vessel Marion Dufresne since her midlife refit in 2015 (Rousseau et al. 2016). taking place in March 2016 in the south Atlantic Roaring Forties and Howling Fifties, this cruise provided a full-scale exercise to test, in rough sea conditions, the latest generation of sediment coring equipment. to illustrate the unprecedented quality of long sediment sequences taken with the improved giant CALYPsO piston corer, we compared two deep-water cores collected ~13 km apart on the south African margin (Fig. 1): (1) core MD02-2587 taken in 2002 with the former coring facilities and (2) core MD16-3510 recovered with the new coring facilities.
Over the last 20 years, the PAGEs-endorsed IMAGEs program (International Marine Past Global Change study, http://www. images-pages.org/) supported 18 seagoing expeditions onboard the 120-meter-long Research Vessel Marion Dufresne. this vessel, operated by the French Paul-Emile Victor Polar Institute, was equipped with an in-house-developed, unique sediment coring facility, called CALYPsO, which allowed for the retrieval of high-quality, long marine cores at sites of high sedimentation rates. the vessel currently holds the world record for the longest marine core ever retrieved-64.5 m. these cores enabled the comparison of marine and ice-core records at the same resolution for the first time, and tremendously improved the understanding of past oceans dynamics.
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