Quote:
| Originally Posted by Nick Kay Fo simplicity's sake, BSAC's take is you have a max of 300 for any un-broken period of diving.
A period of diving is only broken when you have a 24hr "gap"
Therefore if you were to accumulate 100 UPTDs on each of 3 consecutive days, you'd need to have day #4 as a "break"
However if you look at the RepEx Table, you'll see that there's alot of safety margin built-in
My understanding, is that BSAC did it this way so you wouldn't have to know/remember how many consecutive days diving meant what exposure was allowed (i.e. carry a copy of the RepEx table around with you)
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Hi Nick
This isn't quite the case.
Yes the BSAC tried to simlify things by saying 300 UPTD's per day, rather than the sliding scale of single 1 day exposure, 2 day exposure etc.
The 300 units per day will run indefinately for all consecutive days diving until a 24 hour break occurs, i.e for a weeks continuous diving, a months continuous diving etc. (Not that I am recommending this.)
There are two methods for the interpretation of 300UPTD per day.
Method 1
Start time
09:00 hrs day 1, dives can start & continue (UPTD clock) as long as no more than 300UPTDs are accumulted by 09:00hrs day2
09:00hrs day 2 - clock zeroed - another 300UPTDs available through to 09:00hrs day 3
Continuous as for day 2.
Method 2
Start time
09:00 hrs day 1, dives can start & continue (UPTD clock) as long as no more than 300UPTDs are accumulted by 09:00hrs day2
09:00 hrs day 2, dive planed for 11:00 hrs day 2.
Discard all previous dives up until 11:00 hrs day 1 (24 hours PRIOR to planned dive) as long as the planned dive & the previous dives do not exceed the 300 UPTDs then the dive is 'safe'.
Use this previous acrude UPTD method for all subsiquent dives within the 24 hour period.
Method 2 is the more conservative & less used method, which I used to prefer. (Acquiring my YBOD means I am now more likely to exceed the 300 limit). Method 1 is the more common approach (its easier to apply).
Remember the REPEX table/clock was developed by Bill Hamilton originally. As he stated he made initial assumptions, but no specific testing was made to develop the rules. They have just been applied ever since & become the standard (there was a thread on here previously with alot of this information including Bill Hamiltons original data).
There are other problems to take into account (as stated previously), with uniterrupted diving. Nitrogen loading, Oxygen induced Visual disturbance, earproblems etc.