re: 'exotic' metals?

[Phil Nuytten <72020.572@compuserve.com>]

Hi, Rick:
        The crash frame is normally positioned above the entry hatch/vision
dome and rests on the dome hinges aft and the dome mounting ring forward.
It's purpose is just as the name implies . . .in case you surface under a
floating object (Hull, rig pontoon, chase boat, etc.) It's pretty robust,
but is designed to dissipate the shock, essentially. Lifting is done by pad
eyes welded into the hull for that purpose - and they are capable of taking
many times the hull weight to accomodate shock loading when the lift force
( wave ) falls away while retrieving on board. 
        In order to lock hydraulically onto the hull,( so that it cannot
rotate or pendulum,) from the surface , it is desireable  to attach to the
highest point - the crash frame. We cant have the crash frame permanently
attached to the hull 'cause you have to be able to get it out of the way in
the event that you surface with an emergency and must vacate the sub (fire,
penetrator burn-thru, etc.) before the chase boat gets to you. So we wind
up with a Titanium frame 'cause steel is too heavy and it is latched
seperately to titanium ( what else!) feed thru's  that can be operated from
inside the Deep Worker. All in all. a tremendous, expensive, pain in the
butt! Come by before these subs leave, and I'll show you.
Regards
Phil Nuytten!