by the medical officer.: 20‑4.4.2.2 oxygen is breathed the entire duration of the treatment without any air breaks and is followed by 3 hours of oxygen breathing on the surface. diver descends to 30 feet accompanied by a standby diver, and remains there for 60 minutes for type i symptoms and 90 minutes for type ii symptoms, after this ascends to 20 feet even if symptoms have not resolved, and decompresses for 60 minutes at 20 feet and 60 minutes at 10 feet. oxygen is breathed for another 3 hours after surfacing.: 20‑4.4.2.2 royal navy table 81 - emergency therapy in the water use: emergency in-water recompression when no chamber is available. oxygen is not used maximum depth 30 m (98 ft) for 5 minutes continuous ascent to 20 m at 4.5 minutes per metre continuous ascent to 10 m at 8 minutes per metre continuous ascent to surface at 15 metres per minute run time 4 hours 41 minutes "informal" in-water recompression although in-water recompression is regarded as risky, and to be avoided, there is increasing evidence that technical divers who surface and demonstrate mild dcs symptoms may often get back into the water and breathe pure oxygen at a depth 20 feet (6.1 meters) for a period of time to seek to alleviate the symptoms. this trend is noted in paragraph 3.6.5 of dan's 2008 accident report. the report also notes that whilst the reported incidents showed very little success, "e must recognize that these calls were mostly because the attempted iwr failed. in case the iwr were successful, diver would not have called to report the event. thus we do not know how often iwr may have been used successfully." other tables to be fitted in later lambertsen/solus ocean systems table 7a used in commercial diving for: symptoms that develop at pressure. recompression deeper than 165 fsw (50msw)' or where extended decompression is necessary. depth limit 200 fsw for air. iantd in-water recompression schedules