Deeper 2nd dive - why not?

[boulderjohn]

So, in sort of an Interim Summary:
-Nitrogen loading is one factor contributing to DCS.
-The wise diver will monitor nitrogen loading and plan dives to keep the loading within accepted limits.
-It really doesn't matter in what sequence dives are done; deep-shallow, shallow-deep, deep-deep, shallow-shallow, as long as nitrogen loading is accounted for in dive planning.
-Dive Planning doesn't begin and end with the dive sequence. It begins when the diver begins preparation for diving and ends when all effects of any dives have ceased to affect the diver.
-The diver should not forget other factors that affect the diver's health and wellbeing.

I did a search and found a number of earlier threads on this issue, including some that were initiated by Doc Deco, who is an expert.

The consensus of those threads seems to agree with your summary.

 

[Thalassamania]

The diver is in a postion that they cannot go back to a manual table and must stick with the electronic table until they are free of the surface interval obligation. Other than that I haven't found anything in research that would seem to make this dive sequence any more hazardous than doing the dives in a deep first sequence.

Am I missing something?

If you go to page 197 of the AAUS Dive Computer Workshop Proceedings you will find a paper by Mike Emmerman on how to get back onto tables from a dive computer.

A historical note that is likely of interest to almost no one: Emmerman and another meeting participant Phil Sharkey independently came up with this same solution prior to the meeting. Since it was Emmerman's paper, Sharkey referred to it as ESP (the Emmerman/Sharkey Protocol) but Emmerman in his gentlemanly way insisted on referring to as SEX (the Sharkey/Emmerman Exchange).

 

[ArcticDiver]

If you go to page 197 of the AAUS Dive Computer Workshop Proceedings you will find a paper by Mike Emmerman on how to get back onto tables from a dive computer.

A historical note that is likely of interest to almost no one: Emmerman and another meeting participant Phil Sharkey independently came up with this same solution prior to the meeting. Since it was Emmerman's paper, Sharkey referred to it as ESP (the Emmerman/Sharkey Protocol) but Emmerman in his gentlemanly way insisted on referring to as SEX (the Sharkey/Emmerman Exchange).

Actually my mentioning the problem of going back to manual tables from a dive computer was as a very minor aside. I am aware there are methods of doing so. But, the training I've been exposed to all insists that the diver wait out a given surface interval before doing so.

Plus, just about every serious diver I'm aquainted with eliminates the problem by either using two computers, or using a manual table like VPlanner and a bottom timer with a backup bottom timer(a watch). So it really is an academic matter or little practical impact.

By the way, looked at your profile. You sure are young looking for a guy who has been diving since 1956:; Must be that taxonomy, eh?

 

[Thalassamania]

Actually my mentioning the problem of going back to manual tables from a dive computer was as a very minor aside. I am aware there are methods of doing so. But, the training I've been exposed to all insists that the diver wait out a given surface interval before doing so.

I know it was an aside and I was trying to answer it as such.

Please consider broadening your exposure. I would put much more stock in the attendees of the cited conference then in the materials of any of the training agencies or, for that matter, any recreational diving instructor.

Actually just about every serious diver on just about every serious dive eliminates the problem by using no computers; they use tables, timers and good planning. The only place for computers is for poking around in a rather unplanned way with a meandering depth profile, which I do on occasion, such as when engaged in blue-water zooplankton collecting.

 

[WarmWaterDiver]

Hmmm - the folks at Bikini Atoll seem to do serious diving, as do their guests, and allow zero, one, or two computers per diver. There was a nice TV program on last evening on diving at Hawaii and Bikini - a yellow Dive Rite NiTek3 was very visible on the narrator's wrist (I belive this was filmed prior to the Bikini operator upgrading to NiTek He models as rental computers available).

When I'm on a one to two week dive trip, for me, two computers are quite handy - even on 'recreational' profiles - which still constitute serious diving in my viewpont. The $$$ and time availability for such a trip to occur made the payout for the second computer pretty easy math for me to justify.

 

[ArcticDiver]

...Actually just about every serious diver on just about every serious dive eliminates the problem by using no computers; they use tables, timers and good planning. The only place for computers is for poking around in a rather unplanned way with a meandering depth profile, which I do on occasion, such as when engaged in blue-water zooplankton collecting.

Ahhh...the Great Computer/Tables Discussion. From your language you are biased against taking your computer with you when you dive. Others, just as serious, take theirs with them. To me it doesn't matter how a person plans and executes their dives. As long as they plan and then follow the plan.

I've given up even discussing the merits, or lack thereof, of any given dive planning tool. Anyway such discussion is way off the purpose of this thread.

Now if you come to Alaska, or I come to your side polar region I'll be happy to buy my share of our after diving libations and discuss to our heart's content, or at least until chemistry takes full effect

 

[Thalassamania]

I may have to take you up on that, I love the arctic.

The two best diving cruises I've had were in the realm of the midnight sun: Iceland north to the ice then west to Greenland, south to Cape Farewell and up the Davis Straight to the ice again, then thence to St. John's as well as a trip on a Soviet nuclear Icebreaker from Murmansk to the Pole and down into your north pacific to Vladivostok. Skinny-dipping at the North Pole was a real kick in the head.