Concept Development for electrically driven Tow Point for Seismic Operations

Abstract

Rolls-Royce Marine DMSS developed this master s thesis as a part of a process to electrify seismic equipment. Following customers demand, this project involve converting all hydraulic driven seismic equipment to electrical drive. The motivation behind electrically driven handling equipment is eliminating the risk of hydraulic oil contamination to seawater, and improving system handling characteristics to minimize risk of damage to the seismic cables handled by the equipment being used today

A product developed by Rolls-Royce Marine DMSS, referred to as a Tow Point, is a part of the equipment that handles the streamer cable used for seismic surveys. It is located at the stern of the seismic vessel, and works as a suspension point for a (Fairlead) block carrying the streamer cable

This master s thesis delves into the product development process of an electrical driven Tow Point. The main challenge in this thesis has been the size limitations of the vessel and the large torque applied to the motor. Since there is a large difference between the size of a hydraulic motor and an electrical motor, compared to torque capacity, it has been necessary to take a step back, and rethink the Tow Points construction. This thesis shows a step-by-step development process, following the IPM method (Department of Engineering Design and Materials -method), before it concludes with presenting a solution to the problem. The goal is to develop an electrical driven Tow Point with the same capacity and quality as the existing hydraulic driven Tow Points delivered by Rolls-Royce Marine DMSS today, without a noticeable increase in the price. This has been done by presenting several different ideas, performing some preliminary design work of some few of them, and develop further the most promising concept.

The outcome of this thesis is a rejection of two evaluated ideas, and a detailed concept of an electrical driven Tow Point according to requirements set for the product. In the final concept presented, the hydraulic cylinders are replaced with an electrically driven winch.