Filter Units Wind Wave and Tidal Applications

filter units, rock sacks, stone bags, rock bags, mesh net rock bags, flexible rock bags, marine rock bags, subsea rock bags
Kyowa filter unit – Subsea foundation and cable engineering solution

The Kyowa filter unit put simply, is a stone filled mesh net rock bag which can be utilised as a long lasting solution for protecting subsea foundations and cables.  Recognised as an advanced solution to concrete mattress and rock dump,  the product is designed to encase the stone preventing it from breaking down and migrating from its location, therefore is a long term protection solution that omits future remedial works.

The net is made from synthethic material and is available in 3 sizes (2, 4 & 8 tonne) rock bags have a safety factor of 6 and has a one point lifting ring for fast installation.  Unlike concrete mattresses filter units are produced easily and quickly with no down time waiting for concrete to dry or set.



The solution can be installed using high resolution sonar imaging, ROV or by diver.  However, it must be highlighted that a diver in the water is not essential during installation, using ROV or sonar has been proven to reduce H&S risks.

The flexibility of the product makes it versatile and is a proven solution for subsea cable protection.  Studies by offshore developers have proved that the filter unit puts less force on a cable during and after installation therefore eliminating the risk of damaging a cable during installation.  Once installed the structure can be retrieved or decommissioned easily once the cable life has expired or if faults occur.

The Kyowa filter unit has a proven track record in UK & Irish waters as a simple and cost effective solution for OWF subsea asset protection.

If you would like to contact a member of our sales team, please call +44 (0) 2890 454599, or click the button below to send your enquiry via email.

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  • Fast Installation
  • Single point lifting system
  • Significantly reduces vessel time
  • No seabed preparation required
  • Develops marine life
  • Environmentally friendly
  • Accumulates sediments
  • Flexible & durable
  • Rapid preparation
  • Lifetime minimum 50 yrs in saline water
  • Lifetime minimum 30 yrs against UV rays
  • (Also known as subsea rock bags or marine rock bags)

Subsea foundation protection for:




Gravity bases


Subsea cable engineering application:

Cable protection & stabilisation

Cable pinning

Cable underpinning

J-tube support

J-tube underpinning

Bedrock cable stabilisation