Haldane used goats and it was discovered quickly that the 2:1 didn't work. The "real" ratio used is not a water pressure ratio, but one that considers the fraction of nitrogen in air. So a 2:1 water ratio is really a 1.58 ratio of nitrogen pressure to surface pressure. This was later reduced to 1.52 by Workman (for a 240 min. compartment). The current thinking is that it is in the range of around 1.26 (which is about a 1.6 water pressure ratio). While such long times at shallow depths are not really attainable, the numbers used in the model is still an indication of how the model behaves and "slow compartments" can come into play during decompression dives. For example, software programs that consider a 450+ minute dive to 35' as not requiring decompression is an indication of how the model can perform.
