No abstract

In offshore activities, it is necessary for the floating equipment extracting raw materials to reach and maintain a static position along the seabed. Increasingly crucial in these operations is a new type of auxiliary vessel: the anchor handling and supply. While this work is being carried out, the deck gear related to towing and anchor handling-secondary and tugger winches, as well as capstans-play a key role on the anchor handling and supply. To estimate the vessels capacity for taking part in towing and anchor handling tasks, one can turn to the concept of the pull number as the sum total of the traction for this equipment. Linear regression, non-linear and semi-parametric generalised and additive models are adjusted around a broad data base about state-of-the-art vessels. This makes it possible to estimate their value, using as a starting point the vessels main dimensions and power. From this estimate, the traction values for the main and anchor handling winches can be determined. The next step is to propose a way of calculating the traction needed by the secondary, capstan and towing winches assisting the manoeuvre. This study provides procedures and statistical models that can help determine the traction of the towing and anchor handling winches for the anchor handling and supply. These depend on the traction obtained in Bollard Pull testing. The analysis proposed here involves dimensioning the key equipment used on these kinds of vessels so that valuable design information is obtained.

This article discusses the state of the art for driving technologies of anchor handling winches for offshore operations. These systems are necessary for anchor handling operations associated with installation of many types of moored floating offshore structures. To perform these operations, it is necessary to use specialized vessels known as AHT (Anchor Handling Tug) or AHTS (Anchor Handling Tug Supply) vessel, which incorporate specific equipment such as towing winches, but with higher performance than conventional tugs both in size and in technical performance. There are nowadays two main options for driving the Anchor Handling/Towing winches: hydraulic with low or high pressure motors, and electrical with AC motors driven by Variable Frequency Drives. Additionally, a new technology is appearing in the industrial sector which is starting to be applied in the marine sector, and in some cases for anchor handing winches: the permanent magnet motor. The aim of this paper is to discuss these driving technologies and their importance in the future of this part of the marine sector.