rcwild
06-28-2005, 06:54 AM
In canyoneering, there are a number of reasons to set the rope for the length of each rappel. The top two reasons are:
(1) It avoids the necessity of doing wet disconnects. This is especially important in class C canyons where it can be dangerous to struggle with rope and current at the same time.
(2) It is more efficient to deploy only as much rope as needed for each rappel.
To understand how to set rope length properly, it is important to understand some basic rigging systems:
Toss-N-Go
Rope is managed from a coil. Run rope through rap ring, bring rope ends together, coil in hand, throw over edge. Rappel on two strands. When everyone is down, pull rope and re-coil. Not possible to set rope length.
Modified Toss-N-Go
Rope is managed from a bag. Pull end of rope from bag, run rope through rap ring, coil single strand in hand, throw over edge. Next, throw bag over edge. Rappel on two strands. When everyone is down, pull rope and re-stuff into bag. Rope length can be set as long as rope is known to be more than twice as long as the rappel. Does not provide as many options as a block or contingency anchor. Primary benefit: rappelling on two strands of rope provides more controlable rappel.
Single Strand
Rope is managed from coil or bag. End of rope is tied to anchor. If working from a coil: rope is coiled in hand, then thrown over edge. If working from a bag: bag is thrown over edge. Excess rope is deployed because length of drop is unknown. Extremely inefficient. Forces wet disconnects in class B and C canyons. Can be very dangerous in class C.
Block
Rope can be managed from a coil, but much more efficient from a bag. Pull end of rope from bag, run rope through rap ring, coil single strand in hand, throw over edge. Block the rope on the bag side with figure eight knot on bight or with clove hitch on backbone of carabiner (biner block) to fix a single strand. Keep bag with extra rope on top. Last person raps on single strand with rope bag hanging from harness. Retrieval strand is the rope that deploys from bag as he/she rappels. Pull rope and re-stuff bag.
Contingency Anchor
Rope can be managed from a coil, but much more efficient from a bag. Pull end of rope from bag, run rope through rap ring, coil single strand in hand, throw over edge. Set up contingency anchor (i.e. munter hitch tied off with mule or two half hitches, rappel/belay device tied off with mule or two half hitches). Keep bag with extra rope on top. Last person removes contingency anchor and (a) raps on double strands, or (b) sets up block and raps on single strand. Either way, retrieval strand is the rope that deploys from bag as he/she rappels. Pull rope and re-stuff bag.
Setting Rope Length
Of all the rigging systems mentioned, the Block and the Contingency Anchor are the most ideal for setting rope length. The ACA teaches four methods for setting rope length:
Visually
You can see the bottom of the rappel. Coil the rope in hand and throw it down. If too long, pull up on the rope. If not long enough, deploy some more. Simple.
Deploy Too Much
Throw down what you know will be too much rope. First person down must be able to do safe/efficient wet disconnect if class B or C. Signals must be worked out in advance.
-- Standard hand signal for "up rope" is: Point index finger up, make circle with entire forearm, rotating at the elbow. Standard hand signal for "rope length okay" is: Raise arm and make a fist.
-- Standard whistle signals are: Two blasts = "go" for "up rope". One blast = "stop".
Best Guess
Throw down what you think will be the correct length of rope. Set up a contingency anchor. First person rappels to point where he/she can see bottom and can still see a person on top. If more rope is needed, the person on top releases contingency and lowers until "stop" signal is given. Contingency is re-locked and rappeller continues to bottom. If too much rope was thrown down, refer to "Deploy Too Much" above.
Lower the First Person
Set up a lowering system (i.e. munter hitch, rappel/belay device). Tie the end of the rope to the first person (using knot or hitch appropriate to conditions) and lower him/her. Rope length will be set perfectly. Also avoids problems with thrown rope becoming tangled. When first person is down, tie off lowering system so it becomes contingency anchor.
Retrieving a Short Rope
What if you know the rope is too short (less than 2X the length of the rappel) or you're just not sure? With the rope length set using a block or contingency anchor, this is only a concern for the last person down. He/she should rappel on a block. If a contingency anchor was used for everyone else, last person should convert it to a block. He/she rappels on the single, blocked strand as the retrieval strand deploys from the bag. If he/she runs out of retrieval rope before reaching the bottom, he/she locks off, then extends retrieval rope with webbing, cord, shoe laces, bra ... Of course, if there is a concern about the rope length, you should discuss it with your partners before they rappel so you can collect extra material from them, just in case you need it. ;)
(1) It avoids the necessity of doing wet disconnects. This is especially important in class C canyons where it can be dangerous to struggle with rope and current at the same time.
(2) It is more efficient to deploy only as much rope as needed for each rappel.
To understand how to set rope length properly, it is important to understand some basic rigging systems:
Toss-N-Go
Rope is managed from a coil. Run rope through rap ring, bring rope ends together, coil in hand, throw over edge. Rappel on two strands. When everyone is down, pull rope and re-coil. Not possible to set rope length.
Modified Toss-N-Go
Rope is managed from a bag. Pull end of rope from bag, run rope through rap ring, coil single strand in hand, throw over edge. Next, throw bag over edge. Rappel on two strands. When everyone is down, pull rope and re-stuff into bag. Rope length can be set as long as rope is known to be more than twice as long as the rappel. Does not provide as many options as a block or contingency anchor. Primary benefit: rappelling on two strands of rope provides more controlable rappel.
Single Strand
Rope is managed from coil or bag. End of rope is tied to anchor. If working from a coil: rope is coiled in hand, then thrown over edge. If working from a bag: bag is thrown over edge. Excess rope is deployed because length of drop is unknown. Extremely inefficient. Forces wet disconnects in class B and C canyons. Can be very dangerous in class C.
Block
Rope can be managed from a coil, but much more efficient from a bag. Pull end of rope from bag, run rope through rap ring, coil single strand in hand, throw over edge. Block the rope on the bag side with figure eight knot on bight or with clove hitch on backbone of carabiner (biner block) to fix a single strand. Keep bag with extra rope on top. Last person raps on single strand with rope bag hanging from harness. Retrieval strand is the rope that deploys from bag as he/she rappels. Pull rope and re-stuff bag.
Contingency Anchor
Rope can be managed from a coil, but much more efficient from a bag. Pull end of rope from bag, run rope through rap ring, coil single strand in hand, throw over edge. Set up contingency anchor (i.e. munter hitch tied off with mule or two half hitches, rappel/belay device tied off with mule or two half hitches). Keep bag with extra rope on top. Last person removes contingency anchor and (a) raps on double strands, or (b) sets up block and raps on single strand. Either way, retrieval strand is the rope that deploys from bag as he/she rappels. Pull rope and re-stuff bag.
Setting Rope Length
Of all the rigging systems mentioned, the Block and the Contingency Anchor are the most ideal for setting rope length. The ACA teaches four methods for setting rope length:
Visually
You can see the bottom of the rappel. Coil the rope in hand and throw it down. If too long, pull up on the rope. If not long enough, deploy some more. Simple.
Deploy Too Much
Throw down what you know will be too much rope. First person down must be able to do safe/efficient wet disconnect if class B or C. Signals must be worked out in advance.
-- Standard hand signal for "up rope" is: Point index finger up, make circle with entire forearm, rotating at the elbow. Standard hand signal for "rope length okay" is: Raise arm and make a fist.
-- Standard whistle signals are: Two blasts = "go" for "up rope". One blast = "stop".
Best Guess
Throw down what you think will be the correct length of rope. Set up a contingency anchor. First person rappels to point where he/she can see bottom and can still see a person on top. If more rope is needed, the person on top releases contingency and lowers until "stop" signal is given. Contingency is re-locked and rappeller continues to bottom. If too much rope was thrown down, refer to "Deploy Too Much" above.
Lower the First Person
Set up a lowering system (i.e. munter hitch, rappel/belay device). Tie the end of the rope to the first person (using knot or hitch appropriate to conditions) and lower him/her. Rope length will be set perfectly. Also avoids problems with thrown rope becoming tangled. When first person is down, tie off lowering system so it becomes contingency anchor.
Retrieving a Short Rope
What if you know the rope is too short (less than 2X the length of the rappel) or you're just not sure? With the rope length set using a block or contingency anchor, this is only a concern for the last person down. He/she should rappel on a block. If a contingency anchor was used for everyone else, last person should convert it to a block. He/she rappels on the single, blocked strand as the retrieval strand deploys from the bag. If he/she runs out of retrieval rope before reaching the bottom, he/she locks off, then extends retrieval rope with webbing, cord, shoe laces, bra ... Of course, if there is a concern about the rope length, you should discuss it with your partners before they rappel so you can collect extra material from them, just in case you need it. ;)