In this paper Seaway's development project "Underwater Support Vessel for the 1990'ies" is described The vessel is being armed for both the diving and the ROV/ROT market The main characteristic of the vessel is presented, as well as the main topics being studied In the project Further, the following systems have been described more In detail, which partly already are in operation on existing vessels

  • A new concept for hyperbaric diving system (patent pending) The concept consists of 8 vertical identical amber cells configured In a circle, and a turret-based handling system for the bells

  • The DIVEROV concept This diving assisting vehicle, based on a standard ROY has now been In operation over one year The DIVEROV is flexible in the sense that it also can function as an advanced ROV for stand-alone tasks

  • The module handling system now In operation on the DSV "Seaway Condor" This system incorporates both active and passive heave compensation for safe and efficient installation and retrieval of modules on subsea production systems

1. Introduction

The development project "Subsea Support Vessel for the 1990'1es" was started In 1988 In order to coordinate our development efforts within several areas related to diving and ROV operations The aim has been to provide results from the different development areas In such a form that they can be applied to specify Seaway's underwater support vessel and work procedures for the future Some sub-projects have already resulted In systems and methods In operation on our existing vessels

Primary functions for the vessel have been defined as follows.

  • Diving related to IMR, construction work and contingency, especially for deep water diving

  • ROV-operations related to the diving operations and intervention work where the ROV is used as a stand-alone vehicle

Also module handling, well services and laying of cables and flexible flowliness have been defined as functions possible to adopt to the vessel

2. Subsea Support Vessel - Main Characteristics

The following main characteristics/requirements have been defined for the vessel

  • Mono-hull vessel, approx 100 x 20 m

  • Diving system and other equipment dimensioned for state of the art diving to 450 msw, and optimized for diving to 350 msw (continuous diving possible).

  • Deck area min. 800 m2

  • Lifting capacity min 150 tons, active heave compensated

(We are challenging the crane manufacturers to produce a 250 tons crane with same weight and dimensions)

  • Accommodation for min 100 persons

  • Hell-deck

  • Two diving bells, also to be used simultaneously

  • Air diving to be arranged for

  • Work moon-pool min 7 x 6 m

  • Two ROVs on board

  • One for observation purposes and one advanced work-ROV with diving assisting capabilities (DIVEROV, ref Ch 5)

  • Weather criteria for operation of vessel min 40 knots wind and 1, 5 knots current

  • Transits peed min 12 knots

  • Dynamic positioning system to fulfill requirements from authorities and clients as a minimum

  • Active stabilization/compensation heave and rolling movements to be arranged for

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