Highlines - Rope Size/Methods
Well since I have gone crazy in the forums today I thought I would start a new discussion.
My first use of highlines invloved the use of twin 7/16" track lines pretensioned with a flying W (2-2:1 MA's)pulled by one man, and post-tensioned using a 12:1 ratio (4 people on a 3:1).
NFPA comes out with General and light use, and now we use twin 1/2" track lines. Same Flying W pre-tension with a 18:1 post-tenion.
Within the past 2 years I am hearing of FD's using twin 5/8" track lines. Do you pre and post-tension? I have found the Flying W usually puts the right amount of sag and eliminates the need to post-tension. In addition I have been leary of people say they can look at a highline and know how much sag they have.
What do your SOG's say to use for a higline under 400'? Try to support your position with weight calculations or supporting information as to why you use what you do.