Internal Sleeves

1

2

3

4

Drawing number 1 shows the two separate air chambers within the buoyancy tube with the two internal sleeves. The open end of the sleeves are attached to the inside of the buoyancy tube at the same position  where bulkheads would normally be found. Upon inflation of the life raft, these internal sleeves lie flat and uninflated on the bottom of the raft buoyancy tube, because air pressure through the entire interior of the buoyancy tube is equal.

In drawing number 2 there is an air leak in the right hand side of the life raft.  The higher air pressure in the left hand side forces both inner sleeves towards the right. Although buoyancy has been reduced by 50% it is still sufficient to support the rated capacity of the life raft and there has been no loss of floor area.

By using the hand pump in drawing number 3 to force air into the "good" side of the raft, the entire buoyancy tube may be re-inflated to its normal operating pressure and full buoyancy.

Drawing 4 shows the typical single tube life raft that provides two separate air chambers through the use of bulkheads. Unfortunately, an irreparable leak in either chamber results in a substantial loss of floor area, loss of one-half the raft's buoyancy, and loss of canopy support.