Imported post
Hang on chaps we are all getting a bit carried away here.
Deep stops are for deco dives
Doing a deep stop on a non-deco dive and using back gas is not a deco stop. Its an on gassing stop. You dont just bung in deep stops for the hell of it. If you do then expect to get bent unless you have planned them into you’re profile or are following a computer.
Also if you plan dives on a soft where package you will soon notice that from 30m to 60m the first proper stop is usually at 18-24m That is to say a stop longer than 1min. This is because a deep stop below the low M value is detrimental to your profile. So if your doing a 30m dive the low M value is at 21m first proper deco stop is 15m for 3min.
So to plan a deep stop for a 30m dive you would first have to determine the low M value. Having determined it is 21m. You would ascend smartish to 21m say @ 10m/min and then do 3m/min ascent to first proper stop at 15m
This is all well and good but remember that all the time at depth is adding to deco unless you are gas switching so expect the time to surface indicator on your computer to rise and not fall if your doing back gas deep stops. (Unless you have a VR3
)
As an example I did a 40m dive in Gozo on air for 20mins. I left the bottom with 13mins of deco but 6mins later when I got to 9m I still had 13mins of deco. This was because I did not ascend immediately to my indicated deco ceiling of 3m but instead did a slow ascent and added 9m stops to the profile.
In total by the time I had completed deco I had done 20mins since leaving the bottom. That’s fine if you’re expecting it but not if you left the bottom on 50bar.
When Richard Pyle came up with deep stops he was using Bhulman tables that indicated first stop depths after a 60m dive on air for 30mins as 18m with an ascent rate of 18m/min. He then took the 18m stop as his base line to calculate the deep stops. On a no deco profile your first stop depth is sitting on the boat so 6m is a deep stop
Personally if you want to improve your off gassing on a no deco dive to 30m I would cut the base ascent rate down to 10m/ min to 15m then opt for 3m/min to 6m and 1.5m/min to the surface.
Dont bother stopping at all
ATB
Mark Chase