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ROTISII
Remotely Operated Tanker Inspection System II

Ship integrity and pollution prevention call for periodic ship inspections with high costs and risks to those involved. The Remotely Operated Tanker Inspection System (ROTIS) has been developed to enter the flooded ballast tanks (even during ship navigation) to perform close-up visual inspection and wall thickness measurements, using tele-operation from remote sites. The advantages are lower costs (e.g. avoiding ship stand-by), lower risks and reliable results.

Tags: Water

Background

On 4 June 2003, the European Parliament adopted a legislative resolution on double hulls or equivalent design requirements for oil tankers so that old, unsafe and dangerous oil tankers like the Prestige will no longer be allowed to transport oil in EU waters.

In future, heavy grades of oil will be transported by double-hull tankers only.

The introduction of double-hull vessels is widely seen as the response to the need to prevent maritime catastrophes. However, to be effective, it must be coupled with measures towards more efficient and cost effective inspection procedures. Adequate tools must be provided to the surveyors and ship-owners, as well as to state and port authorities providing them with the capacity to perform rapid but safe and reliable inspections.

To date, maritime vessel inspections are based on close-up visual inspections and steel plate thickness measurements. Prior to inspection, a ship must be made fully available at the harbour area, all access spaces must be made safe and prepared accordingly, often in dry dock, thus resulting in a considerable ship idle time and, consequently, a significant cost. In the case of big double-hull tankers it can easily amount to multiples of $100 000.

Objectives

The ROTIS II project will develop a remotely operated underwater vehicle, which is dedicated to ship inspection and certification with a minimum of human intervention and without the need to empty the ballast tanks.

ROTIS II will thus reduce the human intervention in this difficult and dangerous environment and reduce the time for the measurements and reporting in the certification phase as demanded by the classification societies.

The system will address the following operations as requested by the classification societies:

  • close-up visual inspection
  • steel plate thickness measurements.

The ROTIS reference application scenario is relevant to operations inside the ballast area, between the inner and outer hulls of double-hull vessels, with the aim of performing remotely all the inspections required during vessel surveys, taking into account safety and other operational constraints, such as operations in potentially explosive atmospheres.

ROTIS II Remotely Operated Vehicle (ROV) performing inspection of ballast tanks
ROTIS II Remotely Operated Vehicle (ROV) performing inspection of ballast tanks
Tecnomare S.p.A.

Description of work

The ROTIS II system will be made up of the following elements:

  • small, versatile remotely operated vehicle (ROV) equipped with ultrasonic sensor equipment for thickness measurements and a camera system for visual inspection
  • an intermediate unit, providing energy for the ROV based on a proven air generator and high bandwidth wireless communication links to the central unit
  • a rugged and transportable control station for the system providing an easy-to-use human machine interface, the inspection recording equipment and reporting software.

The ROTIS II project includes a significant research effort to correct/meet the technical issues identified by the first ROTIS prototype, which will significantly enhance all the ROTIS functionalities.

Each component and subsystem of ROTIS II is being designed considering the subsequent industrialisation. All subsystems will be finally integrated in an operationally ready, class-approved ROTIS II prototype; particular emphasis will be given to safety and usability issues.

Main research activities:

  1. choice of the correct NDT probe: extensive early testing activities involving various manufacturers and technologies in order to perform plate thickness measurement and coating condition assessment
  2. communication system: new technological developments to get a very thin and neutrally buoyant tether for power and communication, and to design a new tether for the management system
  3. the human machine interface: re-engineering activity to enable the ROTIS II operator to efficiently and quickly perform the high quality inspections in the flooded ballast spaces, with logging of data for future reporting or use in CAD interfaces of the classification societies
  4. vision system: enhancement of the vision system to support the operator in the most critical tasks, such as the centring and passage through the manholes.

Results

The final deliverable of the ROTIS II project will be a complete prototype system, ready for deployment and operation on double-hull vessels by properly qualified operators. The functionality of the system will be tested in conditions as close to reality as possible.

Such a system is expected to contribute significantly in a safe and environmentally benign navigation. It is expected that the availability of adequate tools and methods that will greatly reduce, if not eliminate, the main cost factors (ship idle time and space access preparation) will also make the inspection safer and more reliable.

The possibility of performing tele-operated inspections, i.e. avoiding the direct access of human beings near the structural members to be inspected, is particularly appealing for the following reasons:

  • reliability: reduced logging errors, objective measurements
  • safety of personnel: greatly reduced need to access potentially unsafe spaces
  • economy: elimination of the needs for dry docking and preparing the access spaces can reduce significantly (even eliminate) ship idle time; inspections while navigating can be envisaged.

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