what is bottom time?

[bob1dp]

Let’s say I take 10 minutes to get to 110 feet. Then I spend 12 minutes at 110 and I take 10 minutes to get back to the surface. What is my bottom time?

 

[rakkis]

It depends on what table/algorithm you are using. If using PADI RDP/wheel, then bottom time is defined as the time between the beginning of yoru descent and the beginning of your ascent. (10 min descent + time at depth before making a direct ascent)

i.e.

10 + 12 = 22 mins

 

[do it easy]

For me, bottom time varies depending on what it's for- for the tables, it's just as rakkis described, since that is how my tables work. In my log book, I just lump together total time underwater.

 

[Diver0001]

Let’s say I take 10 minutes to get to 110 feet. Then I spend 12 minutes at 110 and I take 10 minutes to get back to the surface. What is my bottom time?

If you're using the tables then the bottom time is the time from the beginning of the descent to the beginning of an uninterrupted ascent.

Computers generally equate bottom time to the entire time spent under water. This is logical since a computer treats every dive like a multilevel dive.

You should be able to find this information in your openwater book - in the book I have it's in chapter 5 under the topic of using the RDP.

R..

 

[Nemrod]

Bottom time is the time from beginning of descent until beginning of ascent. Obviously multi-level diving complicates this simple definition. In your question, the correct answer would be your bottom time is 22 minutes.

In this scenario using my Navy Tables which are set for the 60 ft/min ascent rate that was standard forever, you have a max no deco BT of 20 minutes. You stayed 22 minutes so you round up to 25 minutes. This gives you an ascent time of a 1 min/40 sec to a 10 foot stop for 3 minutes.

This from my table, not exactly what I would do.

N

 

[ClayJar]

On NAUI tables, your bottom time is the time from when you leave the surface until you return to it (let's just say, it's the time you'd better be breathing on a regulator), but if you so desire, you are allowed to subtract the time spent on your safety stop from the total bottom time.

The dive, as described, would be 32 minutes at 110', which would put you clear off the NAUI tables.

 

[H2Andy]

Let’s say I take 10 minutes to get to 110 feet. Then I spend 12 minutes at 110 and I take 10 minutes to get back to the surface. What is my bottom time?

22 minutes (from beginning of descent to beginning of ascent)

your ascent doesn' count as bottom time

i believe NAUI has a different formula, but i don't know what it is

 

[CrawfishDiver]

Safety stop would be Interruption in direct ascent the way I was taught which means on tables I would be doing a bounce dive at 130 fsw. My SSI tables show 5 min at 130 3min safty sxtop means 2min for down and up. I have always wondered if this was correct

 

[undefined]

Bottom Time is a boat I plan to dive off of in May!



Oh, "bottom time"... yeah, what everyone else said

 

[Doc Intrepid]

Remember the tables, and computers for that matter, are estimating a value that describes "residual nitrogen" expressed as time you must spend on a surface interval before a repetitive dive (RNT).

On the way down and until the ascent you are 'on-gassing' nitrogen - various compartments absorb nitrogen at various rates. At a certain point during your ascent you begin 'off-gassing' nitrogen - impacting your 'residual nitrogen' value. Tables will consider that (logically) while 'off-gassing' during the ascent you are no longer loading tissue groups with nitrogen.

This is why tables define 'bottom time' as from the beginning of the descent to the beginning of the ascent.