I have a spool of 2mm Dyneema about 15-18 foot long. About 6 feet is all ready wound on the spool then a figure nine followed by a 'prussick knot' loop is attached. 12 feet or so down the unwound line is another prussick and figure 9 with a few feet of line ready for setting up. The line is wound around the spool as the dyneema is quite stiff and it seems to be better winding the line up than wrapping (bit like a fly reel).
When setting the free end of the line is passed around a tree and secured to the figure 9
The line on the spool is unwound to the next tree which has to be a least 12 feet away for the tarp to fit!
The spare line is left neatly on the spool and a the spool hangs! Adjusting the figure 9 is easy if trees are wider apart.
The tarp is secured to the Prussick loop with a mini grab at each end the tarp is free to adust along the tarp line and is pulled really tight.
The detail of the prussick is not shown well here but others have shown them in the gallery. The total weight of the line, spool and figure 9's is 41 grams. If there is really big tree to go round I can usually accommodate it with out any porblem.
After looking at these pics it seems that the loose end of the line after leaving the figure 9 is not tied off, is this how everyone else does it? and has anyone had any trouble with it coming undone?
There are little gripping teeth in the V portion that grab the line; keeps it from slipping.
Thank you very much for your great explanation and pictures. It is very similar to what I was doing. The main difference (big one) is that you are using a separate rope for the prussik which gives a lot more freedom. I tied directional figure 8 loops on the ridgeline itself and it was a pain to adjust them. I will definitely give this a try.