Criterion of reusability of nylon ropes in the TRITON buoy system

Abstract

The TRITON (Triangle Trans-Ocean buoy Network), the Japan's first basin-scale open sea buoy network, is a series of buoys deployed in the western tropical Pacific Ocean and the eastern tropical Indian Ocean by JAMSTEC. The TRITON buoys are equipped with underwater sensors for measuring water temperature and salinity to a depth of 750 m, current, and other meteorological sensors. These observational data are transmitted in real time by satellite communication. These data are utilized for weather forecasts in the world and improve the skill of numerical models, as well as monitoring and better understanding of ENSO (El Nino-Southern Oscillation) and Asian-Australian monsoon. While there is no place for question about significance of obtained data, a large amount of operational expenses are required. Length of mooring ropes used for each buoy maintained every year is so much as order of km and the total expenses on ropes needs for all buoys is also not so small. None the less JAMSTEC has never used the recovered ropes as a practice, because of a lack of the data about properties of the ropes imposed tons of tension after twice mooring periods for almost two years. On that background we reviewed previous results of ordinarily used ropes and carried out another at-sea-test using used ropes. As a consequence we were able to get some data encourage to reuse mooring ropes