Page 210 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition
P. 210

  8.8.5 Construction
Designers must consider the mission requirements, including:
• Power, signal (copper or fiber), strength, water weight
• Torque balanced
• Cross talk (shielded conductor, twisted pairs)
• Need for neutral buoyancy
• Water blocked
• Flexing, including bend-over-sheave and minimum bend radius
If no COTS alternative is available, a designer has choices of how to proceed with a custom cable, including:
• Modifying a COTS cable
• Adapting a similar design
• Creating a completely custom design
Some alternative ways to modify a COTS cable include:
• Bundle multiple COTS cables together
• Add water blocking to increase the depth rating
• Add an overbraid strength member to support mechanical loads
• Add a flotation jacket to reduce water weight
The common ways to modify a similar design include:
• Minor modifications such as:
 Improve electrical/mechanical performance
 Different strength member and/or location
 Add a flotation jacket to reduce cable weight in water
 Create a completely custom design
• Designers can optimize cable performance by:
 Using smaller AWG than standard COTS cable
 Manufacture special performance components
 Adjust weight and diameter to suit application
 Use special materials to increase the operating temperature range
 Use nonstandard twist rates to maximize flexibility
8.8.6 Cable design methodology
Designing a cable requires the engineer to identify the unique system requirements, including:
• Length or depth minimums
• Electrical or optical requirements
• Strength or dimensional limits
• Existing cable handling system restrictions, including bend radius
• Temperature and other environmental conditions
8.8 Underwater cable design 199






























































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