Boulder Relocation and Debris Removal

Combining our expertise with the latest remote technology, we deliver industry-leading solutions

Boulders and debris can pose a significant challenge or developers, potentially leading to extensive layout alterations and rerouting; adding considerable time and expense. Our industry-leading techniques offer a highly efficient solution to the challenge of boulder relocation and debris clearance on site. Applying our years of experience, we created the Subsea Multi-Tool (SMT) ROV; a powerful, cost-effective and flexible deployment platform capable of satisfying various subsea requirements.

SMT-ROV: Powerful and Versatile

Ideal for large-scale debris clearance

Capable of relocating 140+ boulders in 24hrs

About the Subsea Multi-Tool (SMT) ROV

The most powerful tool on the market, The SMT ROV offers a highly versatile and cost-effective solution to the challenge of boulder relocation and debris removal.

The modular design allows for interchangeable tooling, including a 6-tine grab, clamshell grab, mass flow excavator and survey skid. The system offers superior productivity in comparison to a WROV, operating effectively even in high-current environments. With flexible deployment options, the SMT-ROV is capable of relocating 140+ boulders in a 24hr period, depending on the boulder density and deployment method.

The ability to accommodate various inspection and survey sensors simultaneously - including the PanGeo SBI - means the SMT-ROV can also perform post-removal confirmation surveys, potentially removing the need for a survey vessel mobilisation. 


Boulders relocated in 24hrs

0.3m to 2.0m

Boulder relocation capability


Maximum lift capacity

6-Tine Grab

Survey Skid with PanGeo SBI

Clamshell Grab

Mass Flow Excavator

Combining a DP Support Vessel with the SMT-ROV provides the offshore industry with one of the most capable diver-less solutions currently available.

Both the SMT-ROV and SMT-ROV 2 offer exceptional lifting capacity. When deployed using the Active Heave-Compensated Winch with through-frame lift capability, the SMT-ROV can lift up to 15 Tonne, and the SMT-ROV 2 can lift up to 30 Tonne using a vessel A-Frame or crane. This is achieved while using a series of hydraulic tools, performing simultaneous survey and video recording. 

The SMT-ROV also transforms into an advanced survey skid - with or without tracks - delivering accurate survey data to support operations including UXO identification and removal, depth of burial surveys and free-span identification.

DP Support Vessel with SMT-ROV

When designing the SMT-ROV, Hughes Subsea created a versatile multi Transformer Tool that can carry out a wider range of tasks compared to a free-swimming work-class ROV, aligning our services to the offshore renewables and decommissioning sectors.

The systems use a simple hydraulic latching system and interface plate. The additional framework can be used for interfacing larger tools such as MFE’s and when multiple tools are being used on one project, quick-connects on the hydraulic lines allow for rapid tooling adjustments. Power is distributed through a hydraulic valve pack so proportional control can be used.

The SMT-ROV offers exceptional productivity

The SMT-ROV offers exceptional levels of productivity and has been proven to relocate 140+ boulders in a 24hr period

Productivity depends on a number of variables, including the boulder density, the distance between locations and conditions on-site.  Proving highly productive, even in high-current environments, the SMT-ROV has demonstrated the ability to relocate more than 140 boulders in a 24hr period. Using the Tine Grab, it is possible to relocate boulders as small as 0.3m. 

The system can be deployed using one of three methods:

  • Vessel AHC crane deployment with tagging tower
  • A-Frame LARS deployment (20T SWL)
  • Vessel A-Frame system

When deployed through the moonpool, increased operational wave limits for launch and recovery are achieved. 

System Specifications

Dimensions L x B x H (m): 2.1 x 2.1 x 1.6

Motor Shaft Power: 2 x 75 kW Sub-Atlantic HPUs

Available Hydraulic Power: 135kW

Through-Frame Lift Capacity: 15 Tonnes

Vehicle Depth Rating: 4000 metres

Thrusters: 4 x 420 mm Sub-Atlantic

Maximum Thrust: 1000 kgf

Video Channels: 6 (Innova)

Ethernet Channels: 3 + (Innova)

Winch Capacity: 1500 metres

Active Heave Compensation: 15T @ 4 metres (Scantrol)

Auto-Heading: Tritech

Auto-Altitude using AHC: Tritech

Optional Survey Pod Integration: Yes

Dimensions L x B x H (m): 2.15 x 2.15 x 1.7

Motor Shaft Power 2 x 150 kW

Available Hydraulic Power: 300HP

Lift Capacity: 30 Tonnes*

Vehicle Depth Rating: 3000 meters

Thrusters: 4 x 380mm

Maximum Thrust: 1000 kgf

Video Channels: 6

Ethernet Channels: 3 +

Auto-heading: Yes

Optional Survey Pod Integration: Yes

Association of Diving ContractorsIMCA