cool_hardware52
Contributor
Hmm. Yep, I'm willing to pay for safety and deal with the rental hassles (or dive with a single in those instances when no practicable alternative exists), if that's the tradeoff
*Much* harder to rent doubles. Nearly impossible to rent small doubles.
A pair of LP50 steel cylinders is around 10 pounds heavier than an AL-80, right? And you carry a few pounds less lead.
True, the aluminum 30's I doubled up for my daughter are lighter than an al 63, but they are the only pair on the planet I know of. Good luck find any small dubs to rent. Oh and you will need different reg / hose configs for singles vs doubles. That either means swapping hoses / plugs when moving from singles to doubles or have 3 regs, 1 for singles and a set of two for doubles.
I read the reports and am not entirely convinced that the isolator valve provides any net safety benefit because the incidence of tank, valve, and burst disk failures is vanishingly low.
True, but "cheater bar" i.e. non isolated doubles, are much less common today than isolated doubles. Again good luck renting any.
Qualified instruction is a good thing with any equipment, I'll give you that, yes, emphasis on qualified. My (inexperienced) point of view is that regulator free flows and runaway BCD inflators are both a significant contributor to accidents, and the statistics, the anecdotal reports, and the near-miss narratives all bear this out. With doubles, not hard, just close the valve on the offending side and switch to the working reg.
"unfixable" reg free flows are pretty rare and for recreational diving, i.e. free ascent to surface, a free flow is only a nuisance. One can always unplug a runaway BC inflator.
If you really want two first stages and two dip tubes buy a Y valve. An H valve will get you two orifices but only one dip tube. Be careful about European Y valves as tank neck threads are metric, not 3/4 as here in the states. You can take it with you when you travel.
If you decide to go with doubles be sure to practice those valve drills ..
Appreciate your words, wisdom, and perspective
2air
Thank you.
Tobin