Bottom time Figuring presure group

[Tagerisatroll]

I had a question, about my recreation dive planner, and how to use it, because i think I have spotted flaw or an error on my part.

I was planning a hypethetical wreck dive (because the rain won't stop) where most of the wreck is at about 25-35 feet so i was figuring spending about 30mins of my dive at this depth, then moving to the keel of the ship and checking out the rudder and ancor that lays at 40-50 feet for about 10 mins.

Now acording to my dive planner if i did the two dives seperatly the 35 foot dive would give me a preasure group of E.

and the second dive to 50 feet would give me "B" Asuming they where both the first dive of the day.

But because i did them at the same time my end presure group would be "B"

Now this seems like an incorect result.

If I did the dives seperatly with a zero surface inertival I would be in Presure Group "I" after both dives. Which seems like a more reasonable preasure group after a 40min dive.

I'm Using the Padi receational dive planner.

 

[The Kraken]

OK, #1, you do the deeper of the two dives first. Remember???

the K

 

[Diver0001]

I had a question, about my recreation dive planner, and how to use it, because i think I have spotted flaw or an error on my part.

I was planning a hypethetical wreck dive (because the rain won't stop) where most of the wreck is at about 25-35 feet so i was figuring spending about 30mins of my dive at this depth, then moving to the keel of the ship and checking out the rudder and ancor that lays at 40-50 feet for about 10 mins.

Now acording to my dive planner if i did the two dives seperatly the 35 foot dive would give me a preasure group of E.

and the second dive to 50 feet would give me "B" Asuming they where both the first dive of the day.

But because i did them at the same time my end presure group would be "B"

Now this seems like an incorect result.

If I did the dives seperatly with a zero surface inertival I would be in Presure Group "I" after both dives. Which seems like a more reasonable preasure group after a 40min dive.

I'm Using the Padi receational dive planner.

If you're using the RDP it's all square profiles based on maximum depth and bottom time.

Your dive was 40 min to 50 feet, which makes you an M.

R..

 

[Tagerisatroll]

So I would figure My total bottom time for this dive at 40 mins at 50 feet even though I would only be at that depth for 10 Mins?

And of course I would explore the stern first, because its depth is greater then explore the decks at the lower depths. But i still thought you figured your presure group on your actual bottom time not your total dive time?

 

[Diver0001]

So I would figure My total bottom time for this dive at 40 mins at 50 feet even though I would only be at that depth for 10 Mins?

Yes, if you're using the RDP to plan your dive, this is what you need to do.

R..

 

[Diver0001]

So I would figure My total bottom time for this dive at 40 mins at 50 feet even though I would only be at that depth for 10 Mins?

Here's another question for you.....what's the definition of "bottom time"?

R..

 

[Tagerisatroll]

Here's another question for you.....what's the definition of "bottom time"?

R..

Doh, I think you may have nailed it I knew i was doing something wrong, Bottom time, and the length of the dive are the same thing.

Knew i was rusty with working the tables thats why i was doing some practice problems, everything had been working until i tryed to do a compound dive with two depths and i was coming up with clearly a wrong presure group. Thanks for the help.

 

[Diver0001]

Doh, I think you may have nailed it I knew i was doing something wrong, Bottom time, and the length of the dive are the same thing.

Just to be clear, bottom time is the time from the *beginning* of your descent to the *beginning* of a continuous ascent -- ignoring the safety stop.

In other words, when you leave the bottom, the dive, in terms of tables, has already ended.

Do keep in mind, though that you *must* make a clean ascent to the surface. From 50 ft to your safety stop should take you about 1-2 minutes (33 ft per min). If it's slower then you need to add that additional ascent time to your bottom time.

For example. If you leave the 50ft mark at 40 min and you arrive at your safety stop at 46 minutes then you need to add the 4 extra minutes of ascent time to your bottom time. Your bottom time would then be 44 minutes even though you left the bottom at 40 and your clock says 46.....

Follow?

Thanks for the help.

No problem.

Just out of curiosity, why don't you have a computer?

R..

 

[Tagerisatroll]

Got it.

Just out of curiosity, why don't you have a computer?

R..

I've actualy Got one it makes the actual dive alot easier, I just like to try and plan the dives out ahead of time.

 

[m3830431]

That is why God made computers, so you don't get cheated