Flexible compliant line for providing a linkage between a first structure and a second structure

A method of tethering a first structure to a second structure, the method comprising:

• providing an elongate tubular sheath of braided material, the sheath having two ends and being able to change reversibly and repeatedly in length and its braided structure being such that an increase in length of the sheath is accompanied by a decrease in its lateral dimension;
• coupling one end of the sheath to the first structure and the other end of the sheath to the second structure;
• providing an impervious flexible bladder within the sheath, the bladder defining a fluid-containing internal chamber which is acted on by the sheath so that the volume of the chamber varies with the length of the sheath;
• connecting a pressure source to the bladder to pressurise the chamber;
• and
• providing a passage communicating with the chamber and incorporating a restriction;
• so that in operation
• the pressurised bladder urges the sheath to expand laterally and so to contract in length;
• and
• an increase in length of the sheath causes fluid to be exhausted from the chamber through the restriction, increasing chamber pressure and providing a damping force opposed to the increase in the sheath's length.

A submersible linear actuator comprising:

• an elongate tubular sheath of braided material, the sheath being able to change reversibly and repeatedly in length and its braided structure being such that an increase in length of the sheath is accompanied by a decrease in its lateral dimension;
• an impervious flexible bladder within the sheath, the bladder defining a fluid-containing internal chamber which is acted on by the sheath so that the volume of the chamber varies with the length of the sheath;
• and
• a pressure source connectable to the chamber to enable controlled variation of pressure in the bladder and thereby to vary length of the sheath.