I have another question about this. If I use a bungeed backup, is the 40" long enough for share air? I am not cave or wreck diving at this time. I have thought about going to a DIR style setup(it just makes sense to me) with a 50 or 60 inch hose, but I would want to test them to find the right length. I'm 5'7" and I think 70 inches is too long for regular open water dives I do.
40" on a 90° swivel elbow (which DiveRite now sells!) is perfect for routing the primary under your right arm with a bungeed backup for a single tank rig. My buddy and I used this exact configuration for about a year. It works, and IMO its far better than the standard primary and octo configuration most of us learned in OW class. Now, depending on who you ask (really, this seems to go back to how long they've been DIR because some of the guidelines seem to have changed over time), it may or may not be DIR anymore to use the
90° swivel elbow on a 40" hose for open water diving. The problem is that to be really comfortable (i.e. not have the hose constantly pulled at annoying angle) you are going want the 90° swivel elbow. Donating the primary on a 40" does work in an OW environment but does require a little practice. I'd bet if you went and checked right now you'd find the hose for your current octo is shorter than 40". My advice for right now is to not get too caught up if its DIR or not, the real value is in transitioning to donating your primary with the bungeed backup.
Yes, the other options would be either the 5'/60" or 7'/84" primary wrapped around the right side of your chest over your left shoulder, behind your neck and to your mouth from your right hand side (note: behind your neck not around your neck). This is the long hose configuration for tech diving, and its not as cumbersome as it looks at first but it
requires actual practice getting used to deploying it. The seven footer works best for BP/W users, its either routed under the battery pack for your expensive canister light on your right hip, or is tucked into your BP/W harness at that location (a Dalton knife harness also works for some people). Tucking sounds kludgey but in reality works very well for single tank divers who don't carry the expensive HID lights. The five footer doesn't have any extra length to tuck or route, so it just goes under your right arm before going over your left shoulder and behind your neck and around. This works well for some people, and is really the only option for people who dive with BCDs (which don't have a real harness) instead of a BP/W configuration. Yes, there seems to be some discrepancy as to whether the five footer is DIR for single-tank OW dives or whether everyone should go immediately to the seven footer. Again, don't worry about getting too caught up in all that just yet.
Now, if you are still with me... I'll say it again, the important thing here is the bungeed backup and donating the primary. If you take a DIR-F/GUE-F class you'll learn about s-drills and modified s-drills which is simply practicing the air share technique. The primary on a 40" is a bit less than ideal in my experience of doing s-drills if you are trying to keep your trim in check (i.e. stay horizontal instead of going slightly vertical). That's the only downside IRL and is why I only use it occasionally and for the most simple OW dives these days.
But if it were me doing it over again, I would still start with the 40" and a 22" bungeed backup and wait until I was ready for a DIR-F/GUE-F class or had a good mentor before going to the long hose since its really something that's you'll want to have demonstrated for you. From there I would go directly to a seven footer (unless you don't have a BP/W yet and then you'll need the five footer).
If you are really interested in learning about DIR (without all the drama), I highly recommend the book
Dress for Success - By Dan MacKay (GUE.com) and the video
Essentials of DIR (Amazon.com) to get a better feel for how the system goes together.
John
