Guidance on diving umbilical management

Summary

The subject of Diving Umbilical Management has previously been covered in IMCA D010 Diving Operations from Vessels Operating in Dynamically Positioned Mode and Sections 8.22 & 10.3 of IMCA D022 Guidance for Diving Supervisors.

These discuss: length, marking, properties, examination and testing, and the safe deployment and tending of diving umbilicals from conventionally moored or dynamically positioned (DP) vessels and static structures.

This document aims to bring these subjects together in one place and expand on the topic of using an in-water tending point (IWTP) during DP diving operations, ultimately providing a clear explanation of the calculations required for the restrictions to the length of the excursion umbilical during normal and extended umbilical DP diving operations.

In order to conduct DP diving operations safely, it is essential to follow the guidance contained within this document (IMCA D078) as well as that set out in IMCA D010.

Version history

January 2024 Rev. 02 – Texts of point 8) of Section 4 and Section 7.1.1 amended for clarity. Appendix 4 Anchor Pattern Checklist added

June 2023 Rev. 01. – Correction to Figure 29

May 2023 – Initial publication

Contents

• Introduction
• Application
• Definitions
• Philosophy
• General Umbilical Management
• Identification and Treatment of Hazards
  • General
  • Azimuth Thrusters
  • Tunnel Thrusters
  • Propellers
  • Voith Schneider Propeller (VSP)
  • Miscellaneous Hazards
• Main Umbilical
  • Diving Within an Anchor Pattern
• Excursion Umbilical
  • Normal Umbilical Operations
  • Extended Umbilical Operations During DP Diving Operations
• Distance Calculations
  • Plan Distance – Deployment Device / IWTP to Hazard
  • True Distance – Deployment Device / IWTP to Hazard
  • Maximum Excursion Umbilical Length
  • Minimum Excursion Umbilical Length
  • Surface Orientated Umbilical Lengths
• Vessel Hazard Diagrams
• Pre-Job Preparation
  • Excursion Umbilicals
  • Swim Lines
• Swim Line Installation Example Methodology
  • Surface Orientated Diving
  • Surface Orientated Diving with IWTP
  • Closed Bell Diving with IWTP
• References
• Appendix 1 – Distance Calculations Worked Examples
• Appendix 2 – Vessel Hazard Diagram
• Appendix 3 – Example Swim Line Setup Storyboards
• Appendix 4 – Anchor Pattern Checklist