The worlds first – Patent pending


castle ship technical management

the i-rake

The I-intelligent steerable subsea rake for multiple boulders 

Patents filed 2018: P255955GB and US – inventors

CSTML is the world no.1 in I-GRAB and I-RAKE systems. We have the longest track history with more successful projects and more systems available than any other company in the world. Joining forces with Ardmore Craig in 2019 to provide a new tool based on the leading I-GRAB technology and patented design to build and operate the I-GRAB powered seabed I-RAKE. 

Prior to the installation of cables, pipelines and offshore installations/platforms and turbines the seabed must be cleared of obstacles and debris to permit the use of cable ploughs and jack up legs.  This involves the removal of boulders and debris on those routes.

The I-RAKE system:

This is a 65 ton subsea combined I-GRAB and I-RAKE system which both existing technologies into a single tool. The new patented technology creates a reduced cost and increased efficiency solution for seabed clearance.  The new boulder rake requires reduced towing power and therefore reduced fossil fuel burn, and reduces the impact to the seabed by the use of spaced teeth which travel through the seabed in a similar way to an excavator bucker teeth could be pulled through sand or mud, catching the boulders and debris and moving them up into the flat blades of the rake, and off away to the sides.  See the video links (left) to watch the rake in action.

Principle features & benefits of I-RAKE

Weight: 65 tons
Tool Width: 12 Meters
Pulling tension: Nominal 30/40 tons / Max tow load 90 tons / Impact load 150 tons
Extension: 16 M with extension pieces – use of extensions is subject to LARS equipment

  • Steering control – The rake can be steered in order to maintain a heading even in difficult cross current conditions and to provide a more controlled path result when compared to an un-commanded plough.
  • Depth control – Hydraulic elevators permit the elevation of the Rake to be set so only the teeth penetrate the seabed, not the flat blades, and to also permit the pilot (on the surface control) to select the depth the teeth operate to. i..e also permits the amount of tow resistance to be changed according to burial depth. The teeth can also be lifted clear of the seabed for environmentally sensitive areas
  • I-GRAB integration – The I-GRAB unit is an intergral part of the I-RAKE. This I-GRAB head unit provides telemetry, survey, live monitoring and hydraulic power control. (see below)
  • Reduced environmental seabed damage as the majority of the seabed and seabed creatures such as crustaceans and their environments can pass through the teeth and under the blades
  • Reduced weight: The rake will weight in approximately 50 tons. Considerably lighter to launch, recover and tow than any comparable size boulder plough. Saving on the size of vessel to operate, the winch to launch and recover and the fuel needed to pull the rake.
  • Reduced fuel consumptions: The teeth of the Rake are easier to pull through the seabed when compared to a plough type system. Reduced towing resistance means considerable reduced fuel costs. We estimate savings of over 50% on fossil fuel burn.





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