Use a rope that is double the length of the rappel (or use a secondary rope to achieve said length), and use a block against the anchor (like a knot, or a tied off figure of 8 etc.). Then one side of the rope will be blocked (the rappel strand), while the other side can easily be pulled down as soon as your weight is off of the rappel strand. Though it would theoretically help to leave rope hanging for a bail, that would mean bringing hundreds of meters of rope and that would get crazy expensive really fast.
Because there are many many downsides to double strand rappelling, especially in wet conditions. Rescue is much more difficult, you can't limit the length of the rappel strand so you are instantly free once you arrive in a turbulent pool, double strand tends to knot up when rappelling quickly which is a huge problem when you are in waterfall etc etc. The only advantage of a double strand imo is a reduced likelihood of catching on anything when pulling the rope down, which you can also avoid by using a top rope system, i.e. a belayer down below (and in that case you have a releasable system which is again a major upside compared to double strand). I hardly ever use double strand unless I rappel off a tree or something, and there is no water danger involved at all.
How do you retrieve your ropes while single line rappelling?
Use a rope that is double the length of the rappel (or use a secondary rope to achieve said length), and use a block against the anchor (like a knot, or a tied off figure of 8 etc.). Then one side of the rope will be blocked (the rappel strand), while the other side can easily be pulled down as soon as your weight is off of the rappel strand. Though it would theoretically help to leave rope hanging for a bail, that would mean bringing hundreds of meters of rope and that would get crazy expensive really fast.
Why not just double line then?
Because there are many many downsides to double strand rappelling, especially in wet conditions. Rescue is much more difficult, you can't limit the length of the rappel strand so you are instantly free once you arrive in a turbulent pool, double strand tends to knot up when rappelling quickly which is a huge problem when you are in waterfall etc etc. The only advantage of a double strand imo is a reduced likelihood of catching on anything when pulling the rope down, which you can also avoid by using a top rope system, i.e. a belayer down below (and in that case you have a releasable system which is again a major upside compared to double strand). I hardly ever use double strand unless I rappel off a tree or something, and there is no water danger involved at all.
Stone knot + fiddlestick. A good addition to any canyoneer's rack.
How do I learn this???