On 18 June, 2015 - Dirk Hohndel wrote: > On Thu, Jun 18, 2015 at 02:57:59PM +0200, Anton Lundin wrote: > > On 18 June, 2015 - Dirk Hohndel wrote: > > > > > On Thu, Jun 18, 2015 at 08:16:36AM +0200, Robert C. Helling wrote: > > > > > > > > BTW this whole discussion is a bit academic: gas switches without stop > > > > that we are worrying about do not appear in real dives. As no stops > > > > come with short shallow dives for which you would not take additional > > > > gases. Or we could resolve it by stating a gas change is automatically > > > > followed by a stop of at least one minute. After all the gas change > > > > takes some time. Not to mention esoteric topics like the oxygen window. > > > > > > In TDI training you will switch to your "low" deco gas as deep as > > > possible, usually before the first stop. We often dive with trimix, EAN40, > > > EAN80 and the switch to EAN40 will be at 80'/25m or 100'/30m (depending on > > > whether you decided on pO₂ of 1.4 or 1.6 for the deco gas). Which tends to > > > be before the first stop. > > > > > > > I don't really see why some training agencies push such a policy, > > especially if the mod is quite a bit deeper than the fist stop. > > > > We usually just switch at whatever the fist stop after the mod of the > > deco gas is. No reason to stop the whole team and do the switch. > > Switch is done in transition. No stop. And the rationale is to start > breathing the higher O2 as early as possible. >
In my view those 1-2 minutes doesn't matter. If you'd like add a minute 3m / 10ft below your fist stop and do the switch there. > > I know that some divers "on the fly" but I'd say thats a really bad > > idea. Which gas you're breathing is really important and we always > > require the other team members to verify the gas switch before starting > > to breath that gas. > > Yeah, that's not part of the procedures we teach. For better or worse. > Wät. Are you relying on markings on the regs or what to know which gas is which too? Here is the headmaster showing some pupils how a propper gas switch is done: https://www.youtube.com/watch?v=iw8pp7aqsZY Thats the way we do our gas switches. //Anton - anyhow, not that related to Subsurface =) -- Anton Lundin +46702-161604 _______________________________________________ subsurface mailing list [email protected] http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
