I’ve been reading the latest DAN Europe paper on decompression risk factors, and I think it reinforces something many of us have felt for years.
Decompression is becoming less about algorithms and more about physiology.
For decades we’ve debated gradient factors, dissolved gas models, bubble models, deep stops, shallow stops… and while those discussions are valuable, they all have one thing in common:
They primarily describe the DIVE. Not the DIVER.
The DAN paper demonstrates that factors such as workload, thermal stress, surface intervals, and even exercise before diving influence decompression risk. That’s a significant shift in thinking. It reminds us that two divers can perform the same dive and have completely different physiological responses.
That got me thinking about three areas that I believe deserve even more attention.
First, exercise before diving.
The paper identifies exercise before diving as a risk factor, but it doesn’t tell us what kind of exercise, how intense it was, or how long before the dive it occurred.
Personally, I wonder whether we’re looking at a hormetic response rather than a simple “exercise is good” or “exercise is bad” conclusion.
Could moderate aerobic exercise a few hours before diving improve vascular function and prepare the body for decompression?
Could strenuous exercise, on the other hand, create dehydration, glycogen depletion, elevated CO₂ production, muscle damage, and inflammatory stress that increase susceptibility to DCS?
I don’t know. But I think it’s a question worth investigating.
Second, decompression quality.
Most decompression discussions assume the ascent is executed exactly as planned.
Reality is often different. One diver ascends smoothly, maintains depth within a few centimetres, breathes calmly, and arrives at every stop precisely.
Another constantly oscillates through the stops, fights buoyancy, kicks to regain position, breathes harder, and works throughout the ascent.
On paper, both divers completed the same decompression. Did they really?
Perhaps we’ve spent decades evaluating decompression algorithms while paying too little attention to how well the decompression was actually executed.
Finally, planning versus reacting.
This is where I believe the value of Ratio Deco 3.0 becomes increasingly relevant.
Modern dive computers are remarkable pieces of technology, but I’m still perfectly happy diving with nothing more than a bottom timer. :-)
Fundamentally, they are reactive.
They tell you what your decompression obligation has become based on everything that has already happened. They calculate a Time To Surface.
They don’t explain why the decompression obligation changed, or how that change affects the distribution of the remaining stops.
They don’t help you understand the gas implications of those changes or how they affect your gas availability throughout the remainder of the ascent.
They don’t teach you how changes in depth, bottom time, ascent strategy, or gas switches affect the rest of the dive.
Ratio Deco 3.0 approaches a decompression strategy differently.
Before entering the water, the diver already understands:
- where the decompression is likely to occur,
- how the obligation is distributed,
- how much gas each phase of the ascent requires,
- and how to make informed adjustments if the dive changes.
If, during the dive, you deliberately decide to change the plan, RD3.0 allows you to predict both the new decompression obligation and the associated gas requirements before your dive computer, it has to do the change and measure the effect before you can expect a finished recalculation.
The computer remains an excellent instrument—but it should just be one source of information, rather than the sole decision-maker.
To me, that’s the real takeaway from this DAN paper. The future of decompression won’t come from a smarter computer. It will come from creating smarter divers. The algorithm calculates the decompression. The diver executes it.
Here is a link to the paper: https://pubmed.ncbi.nlm.nih.gov/41914190/
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Stay sharp and see you out there ( or online in ZOOM ;-) )
Ben Bos
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Unified Team Diving
Training Thinking Divers
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