Deco Tables discussion

[FreediveWI]

First off, they didn't use V-planner for the dive. They used the Wienke tables that NAUI uses to teach all of their Tec stuff with. Those are the same tables that the WKPP uses on their extreme cave dives. They all employ deep stops, usually starting at 80% of max depth.

NAUI has even started to teach deep stops in their openwater courses- which is one reason why some shops are switiching over to NAUI instead of waiting 10 years for PADI to catch up.

Another thing is making sure that your P02's stay in-line so that is doesn't wind up biting you in the butt later on. This is one of the reasons why many of us no longer dive deep air- by swtiching to mix you keep your P02's down to a reasonable level.

Of course there's always the warmth factor. These extreme dives were done in the South Pacific. Warm water seems to be a bit more forgiving for toxing than cold water enviroments.

As far as profiles go it depends upon what wreck. In the past when we would dive something like the St. Albans we would do a 20 minute bottom time, on air, followed by around 45 minutes of deco, sometimes on air and other times on 02 which was supplied from the surface via a hooka hose. The times were derivied by following the Canadian Navy tables- which just happened to match the old Uwatec computers to within a minute of eachother.

Now, I would use something like 18/45 trimix, or possibly even 21/35, with a 50% bottle and, maybe, an 02 bottle. A 25 minute bottom time would only net me around 25 minutes of deco- I'd have to double check that number but I don't have my D-planner with me.

With something deeper, like the Grace Channon, an air dive would be the same 20 minute bototm time followed by 55 minutes of air deco according to the Canadian Navy tables. Doing the same dive today, with trimix and the same deco gas as mentioned before, my deco time would be more than cut in half.

One thing I started doing a long time ago, as soon as I read about it in Aquacorp's back in the early 90's, was to put in some deep stops on ALL of my dives. On something Like the Willy I would start at the top of the wreck, 60', and pull a minute stop every 10' on the way up. At the end of the day you would be surprised how much more energy I would have. Little things like that make a big difference.

One wreck that was really nice to use triox on, or heliotrox if you will, is the Wisconsin. A 28/30 mix with a couple of deco bottles allows for some nice 45-50 minute bottom times with a deco profile that won't leave you hanging all afternoon.

It's interesting to talk to some of the real old timers. They talk about doing dives to 285' for 8 minutes- as timed by their spring wound movie cameras, and then fly back up the line to deco out on navy tables while breathing welding 02. Sometimes they got bent and other times they didn't. One things for sure is that they found a lot of stuff- which has since been stripped off of the deeper wrecks in the last couple of years.

Since those are some of the more common wrecks around here I leave it there for now.

jon