PADI OW KR 4 weird question

[supergaijin]

This has been bugginh me for years

There's a question in the OW knowledge review (I think #4) regarding minimum surface intervals. For one of the questions, the answer is 0 mins (ie. no surface interval required to make the 2 dives)

Any idea why this question is there? Seems to me to send wrong signals to students and is confusing.

 

[300bar]

IMO.Just to see,IF students know how to read the tables.

It's pure theoretical,so we allways explain.it's not common to do a 0 SI.

 

[Crowley]

Basically I agree with 300bar, I think it's an object lesson. It often generates confusion and sort of reinforces the correct way to read the table. One might argue it lets people know that in some cases, it's perfectly acceptable to drop back down after having to make an ascent for some reason (to determine where you are, for example).

On the other hand, the answer to the imperial version of the same question is not 0 minutes - it's actually a positive number. Therefore what I just said might be complete rubbish, because it seems to me that the imperial question serves very little purpose at all - unless you can say it's acceptable to have a very small surface interval between some dives.

Safe diving,

C.

 

[scubamama5]

The answer to that question is 0-4 minutes. The why, is not explained in the manual.. Have yet to see a diver working a planner on the surface..while getting a fix on the boat. Can't do that deep tho..(OW is restricted to 60') and time is limited..get near the limits and it's a safty stop for you..hope you don't drift too far..Another reason to always know where you are. One of my super buddies once told me "If you can't remember where you're going..don't"

It does take a bit more time to board a boat..change your gear...get a drink of water..work the planner...and get your butt back in..
During lecture, I give the students real world examples of getting to the minimums....like when you drop something (like a borrowed piece of gear) or didn't have something you needed (like battery life in the camera) and need to get back.

 

[Jim Lapenta]

But it makes no difference now since you won't have to know how to use the tables anyway. Just disregard it and let your computer tell when it's safe to go back down. Sorry just could not resist this one. But seriously if a shop or instructor decides to teach computer only and then the students comp does not have the planning feature or it craps out how will they know their nitrogen loading status, required surface interval, etc. Do they just trust the DM? That's been real successful lately hasn't it?

 

[Peter Guy]

Yet one more example of why the time spent on "learning how to use the RDP" is pretty much a waste! (In my always, but ever so humble, newbie opinion.)

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Jim, for the "average tourist recreational scuba diver" (how's that for qualifying!) I'd much rather have them "trust the divemaster" than trust their recollection of how to "use the table" for a dive they've never made and for which the table was not designed (i.e., your typical multi-level reef dive).

 

[supergaijin]

Cheers for the responses- it has been a question for a long time. I tell mys students it's to encourage questions, but it's basically a crap question imo

 

[Walter]

I don't know for sure, but my theory differs from the one already given. I suspect it's a carry over from the late 80s when PADI switched from using the US Navy tables to the RDP. The US Navy tables require a minimum surface interval of 10 minutes. If two dives are made less than 10 minutes apart, the bottom times are added together and it is considered one dive. Since PADI had been using the US Navy tables for over 20 years, I think they wanted to drive home the major change in proceedures with the new tables.

 

[Rhone Man]

It is one of the interesting differences between the algorithms - those based on the RGBM theory would rather you kept a shorter surface interval after a deep dive, because you will get greater bubble formation at the surface than if you followed it up quickly with a long shallow dive.

Never met someone who could switch to a fresh tank in 0 minutes though.