KNOT this!

[ryan_boarder]

Because I don't have double 8's, I was thinking about getting 60m of static 5mm cord to shove in my pack. On rappels I usually use an overhand knot but was curious if, when using different diameter ropes, an overhand loses it's strength? If so, is there a better knot to use that won't slip or lose strength?

[Rockitman]

The problem with an overhand and different rope diameters is not the strength, but rather slippage. When rapping off of two, different diameter ropes, I would make two overhands, butted up against each other (try this at home first) and always leave long (~1') strands.

I would also make the extra line a 7mm static, rather then 5mm, but that's a personal decision...

[PAW]

it depends on the method of rappel that you decide to use.

Because of the major difference in diameter you are better to use a jam knot instead of equally rappeling off of both strands because of slippage.

And in that case youll probably want to use a bigger know like an 8 on a bite and join the 5mm to the bite. This is what I have used on a fairly reg basis and seems to work well. A tibloc and biner make pulling the 5mm rope a lot easier.

[ryan_boarder]

Sorry PAW what do you mean by a 'jam' knot? And to clarify... you're tying figure 8 on a bite then joining the 5mm to the bite with a bowline or something?

also thanks for the reply rockitman

[EnigmaM]

don't go lower than 7.5 mm. the reason is its going to be a huge pain to pull your rope using the 5mm line especially when you're tired. i recommend getting the mammut pheonix (8mm). it could double as one of your doubles for the alpine.