Assuming top belay
1- build anchor with cordlette
2- add gri gri to masterpoint
3- measure out 30 meters of rope ( or whatever you need plus a bit for good luck)
4 - thread gri gri in top belay mode and add backup knot
5 - tie in to end, thread rap device at gri gri., throw rope and rap down
6 - dissconnect rap and you're on belay |