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IMHO you should not waste your hard earned bucks on double 40's. Double 95's or 104's or AL80's are much more versatile. -You can do a 2 dive rec trip on the same set of doubles. With double 40's you would need 2 sets or hope the boat has air. -If you do a deep dive then a shallow you can bring along an extra tank and a trans-fill whip to top the doubles off for the second dive. -Buoyancy characteristics of the 40's are not correct for drysuit use, you would need a weight belt. -Double 95's or 104's are heavy only out of the water. I don't know about you but I configure for the dive, not for the surface. -If you are going through the trouble of using doubles then you will eventually be doing overhead diving. Then the money you spend on a convoluted double 40 rig is wasted. A good idea if you intend to advance to tech diving is to go ahead and get setup DIR and dive all your dives, rec or tech, like this. This way you become one with your equipment, know exactly what your buoyancy is for every dive, know exactly where your equipment is located. And no better way to get used to your equipment than to use it frequently and on lots of low-stress dives. Otherwise stick with a single 80 and plan your dive appropriately. Jim ------------------------------------------------------------------- Learn About Trimix at http://www.cisatlantic.com/trimix/ > From: Art Greenberg <artg@ec*.ne*> > Date: Wed, 5 Apr 2000 20:04:02 -0400 (Eastern Daylight Time) > To: Cam Banks <cam@ca*.co*> > Cc: Techdiver Mailing List <techdiver@aquanaut.com> > Subject: Re: Dual OMS 45's > > On Wed, 5 Apr 2000, Cam Banks wrote: > >> So, what if I had a special set of bands made up to hold the tanks far >> enough apart that I could fit a standard isolator manifold on there. >> Is this just lameness and I should give up the whole idea, or is there >> nothing wrong with it? Thanks. > > Cam, > > My wife dives these when we're doing no-deco profiles and she doesn't feel > like hauling around her 85s. So she's thought this through. Here is her > logic, which I think is sound: > > Since the amount of gas is limited (90 or so cf), overhead engagements are > out (no deco, no wreck penetration). So, if there's a failure that calls > for isolator shutdown, she figures she would just terminate the dive. If > the leak is fast enough to cause her gas supply to be exhausted before she > makes the surface, she'll share gas with her buddy (me). > > Now, about the possible failures. Burst disk or neck O-ring, or maybe one > of the manifold O-rings (assuming the OMS non-isolated manifold, which is > the only one I know of that fits these with the stock bands). All carry a > low probability of sudden in-water failure of significant dimension, > especially in non-overhead environments. We've taken care of the burst > disks anyway. > > Also, the extra 1.5" distance needed will push the cylinders far enough > apart that they would not contact the backplate on backplates with a deep > "v", like the OMS and the nice SS plates made by Roger Lacasse (I don't > know about the Halcyon backplate). The cylinders would be held out "in > space" by the bands. That might introduce some stability problems. > > -- > Art Greenberg > artg@ec*.ne* > > > > > > > > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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