Figure 59 Trenching ROV, courtesy of DeepOcean.
Function
A trenching ROV forms a trench in which to bury the cable. This tool is generally used in post-lay burial but can be used during simultaneous lay.
What it costs*
The provision of the trenching ROV is usually part of the cable installation contract scope.
Who supplies them
The trenching ROV is usually provided by the cable installation contractor, either as part of the vessel or mobilised specifically.
Manufacturers: Forum Energy Technology, Louis Dreyfus Travocean, Osbit, Royal IHC, SIMEC and SMD.
Rental: Dockstr, James Fischer Marine Services and Oceaneering.
Key facts
ROVs can have either a jetting system or a mechanical cutter. A high pressure jetting system is used to fluidise the sea bed and allow the cable to sink to the required depth (only in sandy sediments and softer clays). For rocky or hard clay sea bed conditions, a mechanical cutter is used.
What’s in it
- Pressure and flow water jetting system and/or mechanical cutter
- Power supply and control system
- Propulsion system
- Camera and lighting system
- Sonar
- Cable tracker