UKH

Most 'official'/guidebook sources seem to say a 60m rope is needed to ab in one go to the bottom at Castell Helen, but I've read elsewhere (inc on here) that people have got to sea-level using a 50m. What's not clear to me in those cases though is whether that was on account of using stretchy climbing ropes to give them the required length. So, is it possible to get all the way down on a 50m semi-static? Is there any scope for extra rigging at the top to make this feasible, i.e. extending the set-up between the anchors and 'launch point'? Any advice gratefully received.  

Sorry can't help with the exact length - but I once went down on someone else's in situ static, only to find it didn't quite reach the bottom... That was fun.

I've set it up with a 50m static and it was slightly short (it's a few m above the bigger bottom ledges even with a carefully set up belay). If it was a quiet crag you could do it knowing it's short and just solo off to a belay the bottom, but it's a busy crag and people will use in situ ab ropes assuming they are long enough.

I recently abbed on an old 150ft 9mm half rope, then abbed to bottom using our doubled single climbing rope through a krab on a loop in the half rope from the ledge near the bottom and didn't have to abandon any gear. Even though I put my weight on it before preceding there was an exciting falling sensation as I left the ledge due to rope stretch! The loop would have prevented anyone else abbing off the end.

50M will just reach the scoop at the start of Blanco .Rap & Pel ect.. Also the ledge's at the start of North West Passage ect..  It will NOT reach the ledges that are under water at 1/2 tide.

What he said!

I rig the ab off a long sling so as not to waste any rope though.

Great - just the info I needed, so thanks all. On balance it looks the best plan might be to get a longer rope, do the ab in two stages, or see if there's a rope set up when we get there