Top of the boring machine is 60 ft from the surface, but it's 60 ft high so bottom of it is 120 ft. That's 120/33 = 3.6 atmospheres in the ocean, and my reading of the article above is that it may even be higher here due to groundwater pressure. Anyway, you need decompression at anything over 1 atmosphere given enough time as I recall?
Edit: fascinating machine. So yes, it maintains pressure in front of the drill head to resist ground and water pressure.
Top of the boring machine is 60 ft from the surface, but it's 60 ft high so bottom of it is 120 ft. That's 120/33 = 3.6 atmospheres in the ocean, and my reading of the article above is that it may even be higher here due to groundwater pressure. Anyway, you need decompression at anything over 1 atmosphere given enough time as I recall?
Edit: fascinating machine. So yes, it maintains pressure in front of the drill head to resist ground and water pressure.
http://www.hitachizosen.co.jp/english/pickup/pickup008.html
http://www.ncus.ntu.edu.sg/Events/Documents/SRMEG%20Seminar%...