I've been away from diving for a decade. What major discoveries have occurred in dive medicine and decompression theory since I left?

[Wibble]

I run my planned deco and use my computer as a backup.

I do wear a simple wristwatch computer which I use as a stopwatch for timing my ascents and deco stops.

It’s just a different mindset

(Had updated my post after you replied)

Agreed there's very different mindsets.

 

[flymolo]

(Had updated my post after you replied)

Agreed there's very different mindsets.

The planning software ultimately produces a table which is why I said I think tables and planning software are synonymous for decompression diving. I’m not sure there are a set of hard tables that exist. Maybe the closest thing would be the range plan functionality in MultiDeco or decoplanner

 

[Wibble]

if you dont do a plan, how do you do your Deco and gas planning? Is this a common approach?

A good question.

It varies according to the equipment you're diving; rebreather or open circuit. With rebreathers you effectively have unlimited gas supplies so in theory you could do ridiculously long dives. However, there's many other limits to include in the planning:

• Scrubber times: most rebreathers have scrubber limits over 4 hours and especially in warm water.
• The dive boat skipper: how long can you dive for? Depends on the boat and location, but typically you'll have a good 2 hours or longer if planned and agreed. Certain sites will have much longer dive times due to the target depth.
• Depth leads the decompression schedule: dives to 45m/150ft are around 1:1 (1h bottom time, 1h deco); 60m/200ft are around 2:1 (1h bottom, 2h deco); deeper are 3:1, 4:1, etc.
• Temperature: how long can you be in cold water doing nothing? How long does your suit heater work for?
• Boat logistics: using a lazy shot with trapeze or coming up alone under an SMB -- basically do you have extra deco gas available? Do you need a drop bottle, if so, agree this with the skipper including the signal to throw it in.
• Your preferred decompression model: Buhlmann with which gradient factors? If around 50:70 to 50:80 it will add another few mins at the top stop. If using 30:70 then it'll be longer.
• Gases: diluent types. Are you running separate diluent or sharing it as bailout (aka DilOut)? Have you taken into account max PPO2 at depth, e.g. setpoint of 1.0 or 1.1? Lots of helium in the diluent for a clear head?
• Gases: bottom bailout needs to be cost effective and work at the planned depth. PPO2 must be OK for using it as offboard diluent, possibly higher than diluent. Any travel gases to get from the bottom to the deco stops? How long is the deco time, so do you need more than one decompression bailout gas? What's the optimum bailout decompression gas for this dive? 50%, 60%, 80%, 100%?

When you have all this info to hand, you then sit down with your planner (such as MultiDeco) and run the numbers through. You play with all the scenarios and plug in what you've got and what you may want. Money becomes an issue if diving "abroad" as you're going to pay through the nose for helium and deco gases.

Some people may have a more rigid approach to dive planning where they stick to "standard" gases and procedures. Others will plan taking into consideration all of the above.

 

[flymolo]

A good question.

It varies according to the equipment you're diving; rebreather or open circuit. With rebreathers you effectively have unlimited gas supplies so in theory you could do ridiculously long dives. However, there's many other limits to include in the planning:

• Scrubber times: most rebreathers have scrubber limits over 4 hours and especially in warm water.
• The dive boat skipper: how long can you dive for? Depends on the boat and location, but typically you'll have a good 2 hours or longer if planned and agreed. Certain sites will have much longer dive times due to the target depth.
• Depth leads the decompression schedule: dives to 45m/150ft are around 1:1 (1h bottom time, 1h deco); 60m/200ft are around 2:1 (1h bottom, 2h deco); deeper are 3:1, 4:1, etc.
• Temperature: how long can you be in cold water doing nothing? How long does your suit heater work for?
• Boat logistics: using a lazy shot with trapeze or coming up alone under an SMB -- basically do you have extra deco gas available? Do you need a drop bottle, if so, agree this with the skipper including the signal to throw it in.
• Your preferred decompression model: Buhlmann with which gradient factors? If around 50:70 to 50:80 it will add another few mins at the top stop. If using 30:70 then it'll be longer.
• Gases: diluent types. Are you running separate diluent or sharing it as bailout (aka DilOut)? Have you taken into account max PPO2 at depth, e.g. setpoint of 1.0 or 1.1? Lots of helium in the diluent for a clear head?
• Gases: bottom bailout needs to be cost effective and work at the planned depth. PPO2 must be OK for using it as offboard diluent, possibly higher than diluent. Any travel gases to get from the bottom to the deco stops? How long is the deco time, so do you need more than one decompression bailout gas? What's the optimum bailout decompression gas for this dive? 50%, 60%, 80%, 100%?

When you have all this info to hand, you then sit down with your planner (such as MultiDeco) and run the numbers through. You play with all the scenarios and plug in what you've got and what you may want. Money becomes an issue if diving "abroad" as you're going to pay through the nose for helium and deco gases.

Some people may have a more rigid approach to dive planning where they stick to "standard" gases and procedures. Others will plan taking into consideration all of the above.

standard gasses don't change any of the points you mentioned they mainly address safety issues around po2, gas density, narcosis etc.