Floor Boards and their fixings in Boats

The functions of floor boards in a boat are multiple:
   -a smoothish walkway for its length
   -protection of its underplanks and ribs
   -protecion from rotating shafts
   -a storage space especially for fuel, water and gear
   -a place for ballast
   -a place for keeping provisions cool
   -a convenient place for inlet and outlet cocks
   -a sump for pumps and water draining from wet gear
   -inspection ports
   -slop or bilge water indicators
   -a dust pan or rubbish bin where a lid or closable aperture is made to collect this often with a removable pan underneath
   -runs for pipes and electric cables
   -battery storage and some electric or electronic gear
   -useful planks or platterns which ideally should be able to float
One of the problems I encounted with yachts in the past has been access under these boards. Modern boat builders want their craft to look natty and so these tend to be tight fitted and screwed.
Tight fitting is bad news - I knew a Swan drenched after heavy weather where tight fitting floor boards had swollen and lifted off their fixings. Screwing is fine but my experience is that the countersink holes made for this are filled with dirt obscurring the heads, which themselves are deep under the surface, sometimes of brass which has failed, and snap from the effect of salt.
I think floor boards should be easily removeable in an emergency with the emphasis on 'easily' as doing this in a hooli will be hell in its own right.
I have tried to find an easy way around the problem but there are difficulties.
Floor boards should be fixed so they stay put even in a roll-over or a pitch-pole - the last thing one wants then is them or what they are retaining to be flying around or lost overboard.
Another thing those boards should have is a way of lifting them - usually this is getting a screwdriver or knife blade under one edge or abutment - again not the easiest in bad weather even if you have these at hand. A hole that will admit a good sized finger is ideal.

The above shows the lie of the floor boards raised and in place.

               Another view including one of the coverings to the keel
               housing. The ladder, rather the need for a ladder, gives
               some idea of the  high freeboard on this boat.

  The boards in the foreground show the key holes on

     their edges used for the fixings as shown later, as

well as the fingerholes for lifting them.

                              So now it really comes down to fixings.
               As mentioned above a rapid release of the floor board is important and the diagram below
               shows how this is done.

               The slot and shallow curved depression in the floorboard
                accommodates the round 'bungee' or shock cord stopper.
                The other end of the cord slides easily through the wedge
                that is tucked in the space between the suspended  runner
                (yellow) and the hull (heavy black) and  is knotted in its
                 recessed end.

                To release the floorboard the stopper is lifted up and out
                through the slot. It is the longish length of shock cord in
                the wedge available for stretching that makes this not only
                possible but easy.