Bluewater ropes make Assaultline, its 7/16 static line. It is used by the military. It is also in use by the climbing and caving community. REI and some similar stores will stock it during the summer months. While not saying it is impossible, most climbers, arborists, and cavers I have interacted with have said that thin techcord, etc, could be used, but really is an accessory cord. These high tech cords do not seem to be favored because these cords do not hold knots well and are difficult to work with. Keep in mind, most of the tech cords are around 5mm simply to maintain ANY sort of usability, particularly with braking devices. The common run of the mill climbing accessory cord of 6mm will have a break strength of between 1,500lbs and 2,000lbs. This is significantly stronger than 550 cord. Regular accessory cord costs significantly less than the boutique tech cords, and while having about half the strength, 2,000lbs is nothing to sneeze at. Aside from the difficulty in use, I also understand that one reason traditional climbing ropes of both the static and dynamic variety are as thick as they are to withstand use over time, exposure to the elements and abrasion, and impact from a fall. Just my thoughts....kind of a soap box speech....sorry fellas. P.S. I am nothing more than a dabbler in the climbing arena, however I have the good fortune to have several friends whose lively hoods, and lives, depend on their knowledge of this type of equipment.