Vibration isolation module for towed hydrophone streamer

A method of providing vibration isolation for a hydrophone streamer undergoing a towing force, comprising the steps of:

• accepting said towing force and vibration into a first tension member coupled to an exploration vehicle;
• transferring said towing force and said vibration into a first outboard transition unit of a vibration isolation module;
• damping said vibration in a second tension member extending in a loop between said first outboard unit and a second outboard transition unit;
• transferring a portion of said towing force and said vibration into a third tension member and a first inboard transition unit when said towing force exceeds a first limit;
• damping said portion of said vibration in a fourth tension member extending in a loop between said first inboard unit and a second inboard transition unit, said second inboard unit coupled to said second outboard unit by a fifth tension member;
• and
• transferring said towing force to said hydrophone streamer, said vibration having been damped.

An outboard transition unit for a vibration isolation module, comprising:

• a primary block having a substantially cylindrical cross-section, said primary block capable of receiving a first plurality of tension members into axial channels in said primary block, said first plurality of tension members terminating in said primary block;
• an intermediate block with a substantially cylindrical cross-section and axial radially-opposed pairs of axial channels therein, said intermediate block further having axially-offset crossover channels linking each of said radially-opposed channel-pairs to thereby allow one of a second plurality of tension members to pass through a first channel of one of said channel-pairs, one of said crossover channels and a radially-opposed second channel of said one of said channel-pairs, allowing said one of said plurality of tension members to loop through said intermediate block, said intermediate block capable of allowing two of said second plurality of tension members to loop therethrough free of contact between said two;
• and
• a secondary block with a substantially cylindrical cross-section and axial channels therein corresponding to said intermediate block axial channels, said secondary block capable of allowing ones of said second plurality of tension members to pass through said secondary block axial channels, others of said second plurality of tension members terminating in said secondary block, said primary, intermediate and secondary blocks held in a fixed relative relationship to allow tension present on said first plurality of tension members to be transferred through said primary, intermediate and secondary blocks to said second plurality of tension members.

An inboard transition unit for a vibration isolation module, comprising:

• a first secondary block having a substantially cylindrical cross-section and axial channels therein, said first secondary block capable of allowing ones of a first plurality of tension members to pass through said secondary block axial channels, others of said first plurality of tension members terminating in said first secondary block;
• an intermediate block with a substantially cylindrical cross-section and axial radially-opposed pairs of axial channels therein, said intermediate block further having axially-offset crossover channels linking each of said radially-opposed channel-pairs to thereby allow a second tension member to pass through a first channel of one of said channel-pairs, one of said crossover channels and a radially-opposed second channel of said one of said channel-pairs, allowing said tension member to loop through said intermediate block, said intermediate block capable of allowing said ones of said first plurality of tension members to pass therethrough;
• and
• a second secondary block having a substantially cylindrical cross-section and axial channels therein, said second secondary block capable of allowing said ones of said first plurality of tension members and said second tension member to pass through said second secondary block axial channels, said first secondary, intermediate and second secondary blocks held in a fixed relative relationship to allow a portion of tension present on said first plurality of tension members to be transferred through said primary, intermediate and secondary blocks to said second tension member.