Geoff you're right, Cardiac Hill is a beast to walk back up with a full rig and stages strapped to your back. Best done in two trips. The 40m ledge is a reasonably straight forward dive for those with experience of deeper diving. There is a bouyed shot line leading straight to it so a descent down the line saves time and gets you to 40m relatively quickly. The return trip up the line also gves you a reference and trapeze at 5-6m to fizz off before surfacing. This can be dived with a single cylinder and pony as a redundant air source as the NDL at that depth is only 9 minutes you shouldn't really run out of air if your consumption is good. I find the key is to relax on the descent and control your breathing rate.
Everyone I have spoken to about Dotty all have the same opinion about it being the best inland dive site. The diving on offer ranges from 3m - 6m - 9m over a ridge to a road at approx 23m where there is loads to explore with cars, vans, a boat, blasting shelters and a tunnel, you could get a transit van through, leading to another part of the quarry.
The visibility at this time of year is awsome. I reckon on the far side of the 23m tunnel the vis was a good 15m on Monday surface temperature was about 10C with 4C at depth. Although the surface temp is sure to drop over the coming months so best to stay within NDL as long compulsory stops could get uncomfortable.
Doc, lucky you doing your Trimix. That has to be the way forward to further explore Dotty. New Zealand is going to interfere with my dive plans again early next year as I fly back out to Christchurch on 5 Jan for 14 weeks. At least I'll see two summers this year instead of two winters like this year !!!
I can't wait for 30 December now..