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msbrenne
Apr 29, 2004, 2:57 AM
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I would like to buy a second rope to use with my BlueWater Lightning Pro 9.7 mm 60m. Is it un-safe or at all dangerous to use a 10.5mm 60m rope as the second? My concern is that when rappeling the two ropes would have different friction amounts through the belay device. Will this cause the 9.7 to start traveling back up the belay systen and the 10.5mm to pull down with you?
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moeman
Apr 29, 2004, 3:01 AM
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Another relevant question is what knot is best to use to join two ropes of differing thicknesses. Overhand? Double Fishermans? Triple Fishermans?
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bandycoot
Apr 29, 2004, 3:04 AM
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Fat and skinny went to bed.
Fat rolled over... skinny's dead! :lol:
The friction difference shouldn't matter too much. I don't know about the knot though. I'd feel pretty safe on a double fisherman's though! If you are worried about the friction difference, make sure that the knot is such that the thick rope is through the anchor. That way if the thick rope is pulled harder it will stop at the knot!
Josh
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curt
Apr 29, 2004, 3:04 AM
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In reply to: Another relevant question is what knot is best to use to join two ropes of differing thicknesses. Overhand? Double Fishermans? Triple Fishermans?
Square knot, backed up with a double half-hitch. Next question?
Curt
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lovesclimbing
Apr 29, 2004, 3:12 AM
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haveing diffrent diamter ropes are fine, I belive each of those ropes are singles so I don't know why you would like to use them for doubles if I read your post right. True about the rapping, diffrent diamter ropes will rap at diffrent speeds, one way to get around this is to use only one rope as a rap rope and the other as the lock in the anchor so you can still have a 50-60-70m rap. You can just use a dasiy chain system and lock it with the none rap rope, than the last guy unlocks it and raps down, once on the ground, next staion, the escape ledge you just pull out the dasiy chain and pull the ropes. Good habit if you do this is after the last man has unlocked the dasiy you anchor the bottom of the dasiy rope so there is no chance of a major fauilure. I won't explain this in greater detal on the form because it is a skill you should know and practice befor using and I am not knowen for the best spelling ether.
Safe trip
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lovesclimbing
Apr 29, 2004, 3:16 AM
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Curt wrote:In reply to: Square knot, backed up with a double half-hitch. Next question? Curt
Brave man, I would never use a square knot backed up with half hitch's on a rap. The diamter is farily close so if you chose not to use a dasiy methood than a double fishermans would be your best bet like bandycoot wrote.
Safe trip
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capn_morgan
Apr 29, 2004, 3:20 AM
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rapping on different diameter cords isnt too bad. Doulbe fishermans or rethreaded 8 are probalby the safest ways to connect two cords with different waistlines. An overhand would probably be fine as they would be close in diameter...Im used it to tie two ropes that werent exactly the same. I do seem to recall hearing that its not recomended if you are using a thin static as your second rap line.. Anyone have any real hard facts about this?
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curt
Apr 29, 2004, 3:22 AM
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In reply to: Curt wrote: In reply to: Square knot, backed up with a double half-hitch. Next question? Curt Brave man, I would never use a square knot backed up with half hitch's on a rap. The diamter is farily close so if you chose not to use a dasiy methood than a double fishermans would be your best bet like bandycoot wrote. Safe trip
Brave? No, just smart. You can do whatever you like. A square knot is (by far) the safest method of joining different diameter ropes. This works even where the size difference is considerable like a 11mm rope tied to a 8mm rope.
Curt
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dietzpa
Apr 29, 2004, 4:28 AM
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ehhhhhhhhh......square knot is good, but the square knot where you change the direction of one of the tails is better.
attempt at a better explination:
make the u bend in 1 end.
take the end of the other rope, pass it up the hole
around the other 2 ends
then pass under the part that came up the hole.
man, that probably wasn't helpful, but somebody out there must know the name of that puppy (and be able to recognize my description)
It ends up looking like the knot in a bowline, and finish it off with the half hitches. works like a prize fighter.
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alpnclmbr1
Apr 29, 2004, 5:13 AM
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In reply to: In reply to: Curt wrote: In reply to: Square knot, backed up with a double half-hitch. Next question? Curt Brave man, I would never use a square knot backed up with half hitch's on a rap. The diamter is farily close so if you chose not to use a dasiy methood than a double fishermans would be your best bet like bandycoot wrote. Safe trip Brave? No, just smart. You can do whatever you like. A square knot is (by far) the safest method of joining different diameter ropes. This works even where the size difference is considerable like a 11mm rope tied to a 8mm rope. Curt
A reef knot/square knot is the best way to join two different diameter ropes? Since when?
Can you name one reputable source for that claim?
I can name a few that don't use that knot. Long, Soles, Twight, Ashley.
None of the knot tests that I have seen included that knot in the tests.
From ropers knot page
In reply to: The Reef Knot or Square Knot General The reef-knot is only useful in simple applications. Ashley says "it is a true Binder Knot, for which it is admirable, but under no circumstances should it be used as a bend." It is easy tied and will not jam, so it is always easy to untie. It is used to tie packages, and as a base for he shoe-bow. Sailors used it for binding rolled sails or better reefed sails. And that is where it got its english name from. Americans call it the square knot. Probably because it looks square, or because it was much used on square-rigged-ships, but that is a total guess of me. Its relatives, the granny, the thief-knot and the what-knot all have their purposes, but not as a trustful knot. |
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curt
Apr 29, 2004, 5:30 AM
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In reply to: In reply to: In reply to: Curt wrote: In reply to: Square knot, backed up with a double half-hitch. Next question? Curt Brave man, I would never use a square knot backed up with half hitch's on a rap. The diamter is farily close so if you chose not to use a dasiy methood than a double fishermans would be your best bet like bandycoot wrote. Safe trip Brave? No, just smart. You can do whatever you like. A square knot is (by far) the safest method of joining different diameter ropes. This works even where the size difference is considerable like a 11mm rope tied to a 8mm rope. Curt A reef knot/square knot is the best way to join two different diameter ropes? Since when? Can you name one reputable source for that claim? I can name a few that don't use that knot. Long, Soles, Twight, Ashley. None of the knot tests that I have seen included that knot in the tests. From ropers knot page In reply to: The Reef Knot or Square Knot General The reef-knot is only useful in simple applications. Ashley says "it is a true Binder Knot, for which it is admirable, but under no circumstances should it be used as a bend." It is easy tied and will not jam, so it is always easy to untie. It is used to tie packages, and as a base for he shoe-bow. Sailors used it for binding rolled sails or better reefed sails. And that is where it got its english name from. Americans call it the square knot. Probably because it looks square, or because it was much used on square-rigged-ships, but that is a total guess of me. Its relatives, the granny, the thief-knot and the what-knot all have their purposes, but not as a trustful knot.
All right, all right. I concede it is the knot described by dietzpa above that is the square knot variant prefered for joining different sized ropes together. This is also known (I think) as a sheet bend, rather than a square knot per se.
Curt
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knudenoggin
May 8, 2004, 8:48 PM
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For ropes of unequal dia., the Offset Overhand Bend (cf. Clyde Soles's
new book, _Outdoor Knots_ (Mountaineers publ.)--aka "EDK") is fine for
rappelling, IFF you 1) tie it so that the thin rope is what is first contacted
by the standing parts (loaded ends) at their entry point, and 2) is well
dressed. You can bolster this knot by making a Fig.9 in the thin rope
only, the extra turn of the 9 (over the overhand) giving more resistance
to being pried open. With the ropes so oriented, re diameter, the knot
has more resistance to rolling than in even dia. ropes! --a benefit to
its asymmetry.
The Reef/Square knot should NOT be used, and Two Half Hitches are also
not reliably secure in climbing/caving/SAR ropes (esp. as this knot could
see some rubbing against the wall)--prefer Strangle knots (i.e., "half a
Grapevine").
The Grapevine will also be okay, as the component Strangles operate
rather independently, and need each other only for butt-against resistance.
--knudeNoggin
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apoorva
May 9, 2004, 12:19 AM
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In reply to: ehhhhhhhhh......square knot is good, but the square knot where you change the direction of one of the tails is better. attempt at a better explination: make the u bend in 1 end. take the end of the other rope, pass it up the hole around the other 2 ends then pass under the part that came up the hole. man, that probably wasn't helpful, but somebody out there must know the name of that puppy (and be able to recognize my description) It ends up looking like the knot in a bowline, and finish it off with the half hitches. works like a prize fighter.
yeah, its called a seat-bend knot i think? works real well if you can get it, it took me a while to learn it though. a backed-up sqare knot also does work
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rescueman
May 9, 2004, 11:32 AM
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In reply to: This is also known (I think) as a sheet bend, rather than a square knot per se.
Yes, what was described is the sheet bend which is specifically for joining two ropes of different diameters. But, like the bowline (it's in the same family), it's an insecure knot and needs to be reliably backed up. And half hitches are not a reliable backup.
I would use a double sheet bend for a lifeline and back up both tails with a double overhand knot (what is commonly misnamed half a double fishermans). However, this would make a very bulky knot that is likely to get snagged on pull-down.
So stick with the tried and true double fisherman's, leaving a hand's width of tail on each rope.
- Robert
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vegastradguy
May 9, 2004, 2:40 PM
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the real question, though, is why would you buy a thicker line to use as your second line. i assume you're using the 9.7 b/c its nice and light.
if youre going to get a second line (and not get doubles), either get another skinny line like the one you have or get a static line about 5m longer than the 9.7 (for full rope rappels). I used to use a 9mm static...it was very nice.
join 'em w/ a double fishermans....i guess you could use the sheet bend, but unless it pulls like an overhand, stick w/ the fishermans.
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mmckinney
May 9, 2004, 3:32 PM
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i climb with a 9.8 or a 9.4mm lead line and take a 8 mm static tag line. i use a overhand knot with long tails and have not had the 8mm slip significantly. if i am conserned with the slip , i have the thicker rope thru the rap anchor with the knot on the thin rope side, the knot keeps the ropes from running thru the anchor, but like i said, i have had no problems with the slippingt. my 8mm is about 15' longer than the lead line just for kicks. on full 150 to 200' raps, i will back up the rappel with a prussic or some added carabiners to add some friction to my system.
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coclimber26
May 9, 2004, 3:57 PM
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I use the retraced 8 or in some cases the double barrel knot to join two ropes of different diameters. I still can't understand why you would buy a larger diameter rope to use like a half rope? Why don't you purchase either the same rope that you have or even better a set of half ropes?
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beesty511
May 9, 2004, 6:16 PM
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If you are new here and haven't figured it out yet, for your safety please ignore what curt posts.
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