HANDLING CHARACTERISTICS 105 



36. Pressurize Sealab to 10 psi over bottom pressure with air, or about 100 psi gage. 



Comment: This ends the activities which will be accomplished by the Sealab inhabitants. All 

 other activities will be accomplished by surface divers after the Sealab inhabitants 

 have been transferred via PTC to the DDC and decompression has started. 



Phase 2 



Sealab 11 has been vacated with main access hatch dogged down with one dog, and pressur- 

 ized to 15 psi over bottom, which is about 100 psi gage, depending on tide conditions. Important : 

 Bottom is defined as the lower portion of the pressure hull. The reason for this selection of a 

 depth reference point is that the main access hatch is very near this point. This main access 

 hatch as well as the two other hatches on Sealab must always have positive internal pressure 

 to ensure that they are sealed. This is particularly true of the main access hatch which is 

 large and does not have an internal strongback to resist negative pressure. 



The pneumofathometer hose will be attached to the top rail of the walking flat, which is 16 

 ft above the bottom to the pressure hull of Sealab. Thus, 16 ft must be added to the pneumo- 

 gage to get the depth at the bottom of the pressure hull, the depth reference point. 



Pressure inside Sealab will be measured via the sampling line in the umbilical. Similarly, 

 air pressure may also be supplied to the Sealab via the umbilical. 



Sealab is on bottom with 6 degree port list and trim by stern of 6 degrees, with spades 

 completely dug into the bottom. 



Phase 2 Operations 



1. Move staging vessel over Sealab. This will be about a 55 ft move. 



2. Modify counterweight to handle a 12,000 lb load since it is believed that a minimum of 

 2000 lb of water will be left in C-2 after blowing. 



3. Make all dogs tight on main access hatch. 



4. Ensure that Valve B-3 is closed. 



5. Open skirt vent valve A9 to flood skirt. 



6. Pressurize Sealab to 15 psi over bottom if not previously possible since one dog may 

 not have been sufficient to hold pressure. 



7. Place Gear in moor (2nd day). 



8. Attach pneumofathometer gage hose to top life rail of walking flat. This point is 16 ft 

 above bottom of pressure cylinder. Therefore 16 ft at depth must be added to get depth at 

 bottom of pressure cylinder. 



9. Attach lifting wire to the lifting bridle of Sealab and put on small counterweight to take 

 slack out of lifting wire. 



10. Close flood valves CI, C2, C3 and vent valve A-8. Leave C4 open so that any air ex- 

 pansion in conning tower can be equalized as Sealab is raised. 



11. Check that vent valves A2, A3, A4, A5, A6 and A7 are open. 



12. Check that all valves on topside air salvage system are closed. Open valves Bl and B2. 

 This will equalize pressure between the living compartment and tanks 1,2, and 3. Open valves 

 A-10 and then A-1 to test air system. Then close A-10 and A-1. 



