IMCA Marine Division

Publication Details

Considerations About the Use of Hold-Back Vessels During DP Diving Operations

There may arise situations where, as a result of a risk assessment, it is deemed necessary to provide additional safeguards to prevent a potential loss of position of a dynamically positioned (DP) diving vessel. These safeguards are in addition to the traditional and well established methods, which are also discussed in this guidance. In recent years there have been some occasions where it has been decided that these additional safeguards may include securing a towing vessel to the diving vessel to act as an 'anchor' in the event of the diving vessel losing power or 'blacking out'.

IMCA believes that there are better alternatives in most such situations - seven examples are set out in the guidance. If it is thought that the use of a hold-back vessel may indeed be necessary, the additional risks that this introduces need to be thoroughly considered and addressed. With this in mind, IMCA commissioned the preparation of this guidance document to help members consider these issues, which include, for example, the risk assessment, selection of an appropriate vessel and practical considerations for operational planning. In many cases a thorough review of these issues will identify that there is indeed a better alternative.

Contents

1. Introduction
2. Risk reduction in diving operations
3. Assisted DP diving operations
4. Selection of the hold-back vessel
5. Practical considerations
6. References