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Department Contacts
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Subsea Excavation Services
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Overview:
 The HydroDigger equipment produces a low velocity, high volume column of water, which is directed downwards onto the seabed. As the controlled column of water meets the seabed, it breaks up the seabed formation and disperses the soil laterally. Moving the digger along the seabed creates a trench with a spoil berm either side. In contrast to other dredging techniques, HydroDigger is effectively non-contact; only the column of water makes contact with the seabed or any existing seabed assets.
The HydroDigger’s combination of real-time sonar monitoring and variable excavation power provides precision during excavation projects within constrained areas and long distances. HydroDigger has proven its effectiveness in various seabed formations, such as sand, gravel, silt, drill cuttings, rock dump and clays up to 25kPa.
The excavation capability of HydroDigger can be enhanced by using a high pressure water jetting system; this system operates in parallel with HydroDigger to increase performance in tougher sea bed conditions.
To find out more about the HydroDigger and Fisher Offshore’s subsea excavation services, click here to contact us.
Fisher Offshore’s (Subsea Excavation Services) HydroDigger is a fully integrated system, which is deployed over the side of a client’s vessel and remotely operated from its control cabin on deck. Some of Fisher Offshore’s (Subsea Excavation Services) HydroDigger fleet have a dedicated Launch and Recovery System (LARS); this frees up vessel cranes etc. for other tasks and provides clients with greater flexibility in terms of vessel type and allocation of deck space.
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 Subsea Excavation (Video / .mov files)
If you do not have the Quicktime for Windows loaded to play (.mov files), please click here to download it free.
 What is QuickTime? Have you ever wanted to watch a video or listen to audio online, only to discover your computer can’t play the file? That’s why you need QuickTime. It’s powerful media technology that works on Mac and PC with just about every popular video or audio format you come across. So you can play the digital media you want to play. A A free download is available above.
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| Seabed Preparation: The HydroDigger, Fisher Offshore’s mass flow subsea excavation system, can assist with seabed preparation in a ways, including:
- Sand wave levelling
- Burial of seabed obstructions
- Glory hole excavation
Please click to view movie.
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| IRM (Inspection Repair and Maintenance: The HydroDigger, Fisher Offshore’s mass flow subsea excavation system, can assist with inspection, repair and maintenance tasks as follows:
- De-burial of subsea assets
- Rock dump removal
- Channel maintenance
- Location and burial of dropped objects
Please click to view movie.
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| Pipelay: The HydroDigger, Fisher Offshore’s mass flow subsea excavation system, can assist with pipelay work, includins:
- Lay trenching
- Free-span and crossing correction
Please click to view movie.
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| Decommissioning: Fisher Offshore’s mass flow subsea excavation system, the HydroDigger, can assist with decommissioning projects, includings:
- Exposure of piles and drill templates
- Burial of redundant structures
Please click to viewmovie.
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| Subsea Clearance: HydroDigger, Fisher Offshore’s mass flow subsea excavation system, can assist with subsea clearance work as follows:
Please click movie (with conrols) to view. Non-contact excavation/clearance of manifolds, well heads, valves, pipelines and any other sea-bed based equipment or structures that need to be accessed or kept clear of debris or soils.Re-excavation of existing glory holes.
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