Oceanic Cable Block

IN6989.250 – Cable ∅ – 6 mm
IN6989.322 – Cable ∅ – 8 mm
IN6989.375 – Cable ∅ – 9.5 mm
IN9417.750 – Cable ∅ – 19 mm
IN11118.680 – Cable ∅ – 17 mm
IN11118.563 – Cable ∅ – 17 mm

Light Enough to Align the Load

Harken Industrial Oceanic Cable blocks are used on research vessels to safely lead data cables and towed objects overboard. At only 19.3 kg (42.5 lb), the 500 mm (19.7″) sheave-diameter block is light enough to align to the load, optimizing cable tracking.

Oceanographic Research

The Oceanic Cable block is used by Woods Hole Oceanographic Institute, University of Rhode Island (USA), and University of Alaska – Fairbanks oceanographic research departments, as well as many other research organizations.

Easy Maintenance

Flushing the block with fresh water after use will keep the dry-running bearings free rolling. If further maintenance is required, one hex wrench is all you need for disassembly. All the bearings are captive, so no need to worry about losing parts.

Oceanic block durability


Sideplates are constructed of hardcoat-anodized 6061-T6 aluminum for strength, durability, and corrosion resistance. They are PTFE-coated for a smooth surface.

Oceanic block bearings


Delrin® roller bearings are housed in a center cage to keep them parallel for low-friction efficiency. The large diameter bearing cage reduces friction and spreads the load. Captive Torlon® ball bearings handle sideloads.

Oceanic block large diameter sheave

Large Diameter Sheave 

The block’s open center helps move the center of gravity toward the shackle, improving the block’s ability to align with the load. The sheave’s groove detailing can be designed to suit specific data cable diameters.

Oceanic block Design


The block’s wide throat allows passage of data cable terminals. The sheave’s durable, lightweight Nylatron® material has high mechanical stiffness, resists static electricity, and has excellent wear resistance. Plastic isolators and helicoils are used to minimize corrosion between aluminum and stainless steel. The Oceanic cable block is UNOLS compliant.

Oceanic block options


The block is designed to work with an optional magnetic Hall Effect Sensor.

Product Details

Cheek gap
Weight Max
Rated Load
in mm in mm in mm lb kg lb kN
IN8260 20 500 2.25 57 0.25 6 42 19 19000 84.5
IN12771.322* 20 500 2.25 57 0.322 8 42 19 19000 84.5
IN6989 20 500 2.25 57 0.338 8.5 42 19 19000 84.5
IN8355 20 500 2.25 57 0.375 9.5 42 19 19000 84.5
IN6989.590 20 500 2.25 57 0.59 15 42 19 19000 84.5
IN9417 30 750 4 101.6 0.75 19 150 68 40000 175.5
IN11118.563 30.5 775 4 101.6 0.563 14.3 233 105.68 80000 355
IN11118.680 30.5 775 4 101.6 0.68 17 233 105.68 80000 355

Compliant with UNOLS Research Vessel Safety Standards, Appendix B * Freeze tolerant version


Oceanic cable block case study


Nylatron is a registered trademark of the Quadrant Group.
Delrin is a registered trademark of E.I duPont de Nemours and company or its affiliates.
Torlon is a registered trademark of Solvay Advanced Polymers.



IN6989.322 = 19kg (43lbs); IN6989.250 = 19kg (43lbs); IN6989.375 = 19kg (43lbs); IN9417.750 =68kg (150lbs); IN11118.680 = 105.68kg (233lbs); IN11118563 = 105.68kg (233lbs)

Max rated load

IN6989.322 = 84.49kN; IN6989.250 =84.49kN ; IN6989.375 = 84.49kN; IN9417.750 = 175.66kN; IN11118.680 = 355kN; IN11118563 = 355kN

Q: Is the Oceanic Cable block compliant with any industry bodies?

A: Yes. It is compliant with UNOLS Research Vessel Safety Standard, 10th Edition 2015.

Q: Does Harken Industrial provide a Maximum Capability Document?

A: Yes. Please contact Harken Industrial.

Q: What linear speed can it handle?

A: 60 m/min (196ft/min).

Q: What is the lifespan of the block?

A:Harken Industrial recently serviced some 10-year-old blocks. Regularly flushing the blocks with fresh water will help extend their life before service is required.

Q: Do you offer alternative sheave diameters?

A: Yes. The sheave groove detailing can be designed to suit specific cable diameters. Please email your requirements for a quote.

Warnings and Instructions

The users must follow the manufacturer's instructions for each component of the system. These instructions must be provided to the user of this equipment. The user must read and understand these instructions before using this equipment. Manufacturer's instructions must be followed for proper use and maintenance of this equipment. Alternations or misuse of this equipment, or failure to follow these instructions can result in serious injury or death.