Flotation platform

Bifacial inflatable life raft structure defining a plurality of boarding stations equally useable by evacuees irrespective of facial orientation of the structure upon a body of water. Sea ballast structure with such a life raft is also disclosed.

BACKGROUND OF THE INVENTION 
The field of this invention is flotation platforms, particularly of the 
inflatable variety, and method of making and using such flotation 
platforms. With still more particularity, the invention relates to a 
bifacial specie of inflatable life raft presenting a multitude of boarding 
stations by which an evacuee may enter the raft unassisted, and which also 
provide purchase for able-bodied evacuees aboard the platform to assist an 
injured or otherwise disabled person to board the raft. 
Conventional inflatable life rafts are known which are bifacial. That is, 
the life raft when inflated and upon the surface of the sea presents 
substantially the same utility and serviceability with either side up. 
Further, a conventional bifacial life raft is known which presents a pair 
of boarding stations whereat evacuees may conveniently leave the sea and 
board the raft. For example, a life raft of such character is known 
according to U.S. Pat. No. 2,933,739, issued Apr. 26, 1960 to R. L. 
Miller, et al., wherein the life raft is composed essentially of a stacked 
pair of open-centered inflatable ellipses sandwiching a panel of fabric 
therebetween. The fabric panel defines a floor for the raft. The ellipses 
are rotated relative to one another and secured together so that the major 
axes of the ellipses are disposed perpendicularly to one another. The raft 
thus defines four boarding stations; a pair of which are useable with one 
face of the raft upward, and another separate pair of which are useable 
with the other reverse face of the raft upward. An inflatable step is 
provided at each boarding station. 
Life raft constructed according to the teaching of Miller, et al., are 
believed to have many deficiencies. For example, the raft has only a pair 
of boarding stations which are usable at any one time. This feature of the 
Miller, et al., raft limits the rate at which the potential occupants may 
leave the sea and board the raft. After a ship wreck or airplane crash, 
there may be a multitude of persons in the sea, many of which may be 
injured and of short endurance. A delay in boarding an available life raft 
may mean death for injured or weakened persons who simply cannot struggle 
for life or tread water long enough while waiting for help or for their 
turn to board the raft. In the confusion and fear surrounding such 
tragedies, weakened or injured persons may simply slip beneath the waves 
and their loss go unnoticed at the time. 
Further, a life raft according to the Miller, et al., teaching is believed 
to be comparatively bulky and heavy with a plurality of seams. Such is the 
case because the ellipses of the raft body are in fact defined by 
plurality of relatively short, straight tubular sections which are jointed 
to one another. Thus, each of the straight tubular sections must define a 
seam with each of its neighboring adjacent tubular sections. Such a 
multitude of seams adds both weight and bulkiness to the raft, and each 
seam presents the risk of a leak in the raft. The bulk and weight of a 
raft according to Miller, et al's teaching is increased still further by 
the inflatable step section provided at each of the four boarding 
stations. These step sections are four in number, although only two of the 
steps may be utilized at a time dependent upon which side of the raft is 
upward. Thus, the other two unused step sections are truly superflous bulk 
even though they are necessary with the life raft of Miller, et al. 
Yet another shortcoming of the Miller, et al., life raft is believed to be 
its considerable difficulty of construction. That is, the life raft of 
Miller, et al., requires a plurality of straight tubular segments to be 
formed and joined with a plurality of seams therebetween. Thus, a large 
number of separate pieces of body fabric must be cut, fitted to one 
another, and joined by leak-proof seams to construct a life raft according 
to the conventional teaching. All in all, the life raft of Miller, et al., 
is believed to be inherently intensive of both labor and materials. 
Further, a basic need has been recognized for a new type of life raft. This 
new specie of life raft is herein referred to as a flotation platform. The 
principal use envisioned for flotation platforms is aboard aircraft, even 
though they may also be used aboard other craft. Presently, aircraft which 
fly over bodies of water and more than 150 miles from shore are required 
to carry conventional life rafts and survival gear. However, aircraft 
which fly over water but never more than 150 miles from shore are required 
only to carry flotation assistance equipment, such as boyant seat cushions 
and inflatable life vests. 
However, experience has shown that aircraft passengers placed into the cold 
sea by an aircraft wreck with only flotation assistance equipment have a 
very poor chance of survival because of exposure and hypothermia. Even 
though rescue equipment and assistance may require only a few minutes to 
reach the scene of the aircraft wreck or ditching, passenger survival 
rates may be very low. Thus, there has been recognized a need for a 
flotation platform which is relatively light in weight and low in deflated 
package size and bulk. Such a flotation platform may be carried aboard 
aircraft not designed to carry more than flotation assistance equipment, 
such a boyant seat cushions. Such a flotation platform need not provide 
facility for long-term occupancy. That is, water and food need not be 
provided, and extensive environmental sheltering for those aboard the 
platform need not be provided 
Further, it is recognized that an optimized flotation platform will allow 
able-bodied evacuees to leave the sea and board the platform quickly. 
Additionally, such a platform should provide purchase for those 
able-bodied evacuees already aboard the platform to assist other evacuees 
in the sea, who may be suffering from injury or hypothermia, to board the 
platform. Still further, such a platform should include bifacial sea 
ballast structure which will assist in stabilizing the platform to 
increase occupant comfort and safety. 
SUMMARY OF THE INVENTION 
In view of the many deficiencies of conventional life rafts, only a few of 
which have been pointed out above, it is a principal object for this 
invention to provide a bifacial life raft which is both relatively light 
in weight and relatively easy to construct while providing as large a 
number of boarding stations as talent and human ingenuity will provide, 
and which through aspects of its conformation minimizes the number of 
seams required in its construction and the risk of leakage presented in 
use. 
Yet another objective of the present invention is to provide a life raft of 
the above-recited character which is comparatively light in weight and of 
no greater bulk in its deflated, folded condition than is dictated by the 
contraints of currently available materials used in its construction. 
Still another object for the present invention is to provide a life raft 
wherein a plurality of boarding stations are inherently defined by the 
raft without the need for conventional expedients such as inflatable step 
sections which add superfluous weight and bulk to a life raft. 
Yet another object of the present invention is to provide a life raft of 
the above-cited character which provides sea anchor and stability 
augmentation structure also of a bifacial nature, and which structure does 
not interfere with the utility and passenger comfort provided by the raft. 
In view of the above, it is a further object for this invention to provide 
a flotation platform of the above-described character which allows 
evacuees to quickly leave the sea and board the platform. According to a 
particularly disclosed preferred embodiment of the invention set forth 
herein this objective is fully met by the provision of eight boarding 
stations presented to evacuees regardless of the facial orientation of the 
platform upon the sea. 
Further objects of this invention are to provide a method of constructing 
and a method of using a life raft of the character described. 
To this end, the invention provides a bifacial life raft comprising a 
stacked pair of flexible, gas distensible and open-centered similar 
polygons secured to one another and to a panel of fabric sandwiched 
therebetween, the panel defining a floor for the raft. The open-centered 
polygons are secured to one another with an apex of each substantially 
congruent with a side of the other so that a crotch or crevice is defined 
between each adjacent pair of apexes. Each of the crotches defines a 
boarding station for the life raft whereat the underlying polygon 
inherently cooperates with the upper of the pair of polygons to define a 
boarding step or step-like crawlway by which passengers may board the raft 
from the sea. 
Further, between each adjacent pair of boarding stations, an apex of one of 
the polygons protrudes outwardly beyond the adjacent side of the other of 
the pair of polygons. Each such protruding apex provides an area of 
purchase whereat a passenger already aboard the raft may conveniently 
assist a person in the sea at one of the adjacent boarding stations to 
board the raft. A particularly beneficial aspect of this feature is that 
each crotch, each boarding station, is in fact disposed between a pair of 
protruding adjacent apexes. Thus, a pair of passengers may work from the 
pair of apexes to assist a weakened or injured person in the crotch 
therebetween to board the life raft. 
A preferred disclosed embodiment of the invention comprises a pair of 
stacked open-centered squares sandwiching a panel of fabric therebetween. 
The open-centered squares are substantially identical and each comprises 
flexible tubular gas distensible structure which is substantially circular 
in cross section. The open-centered squares are secured to one another and 
to the floor panel therebetween with the apexes of each substantially 
congruent with the side centers of the other. A plurality of straps and 
handholds are secured to the tubular structure so as to provide equal 
facility for passengers to leave the sea and board the raft irrespective 
of which side thereof is upwardly facing. 
Additionally, a particularly disclosed preferred embodiment of the 
invention presents bifacial sea anchor structure comprising a 
substantially triangular web of fabric slackly spanning each inside corner 
of each open-centered square. In other words, on each face of the 
flotation platform are four slack triangles of water-holding fabric which 
each cooperate with the remainder of the platform to define a pocket for 
trapping sea water. Because the fabric webs are slack, the four webs on 
the upward face of the platform may lie loosely in the corners of the 
platform without interferring with use of the corners of the platform by 
evacuees. 
Further to the above, a method of making a life raft according to the 
invention and a method of using the inventive life raft are disclosed. 
Additional objects and advantages of the present invention will be 
apparent in light of the following detailed description of preferred 
embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 depicts a particularly preferred embodiment of the invention in its 
inflated condition as it would appear upon the surface of the sea when 
viewed from directly overhead. The flotation platform 10 will quickly be 
seen to appear as an octagonal star having eight points and sixteen sides. 
However, closer examination of the platform 10 will reveal that it 
comprises two substantially identical open-centered gas inflatable squares 
12 and 14, which are stacked and secured to one another. The squares 12 
and 14 are each defined by four substantially straight tubular inflatable 
sections of flexible air-proof fabric. The tubular sections have a 
generally circular cross-section. Each of the tubular sections of each 
square 12 and 14 is in gas communication with its adjacent tubular 
sections at the mitered corners of the squares 12,14. The squares 12 and 
14 are secured to one another so that the apexes of each is substantially 
congruent with the center of the sides of the other square. Accordingly, 
viewing FIG. 1 it will be seen that because each square 12,14 has four 
apexes or corners, the angle of relative rotation between the squares 
12,14 is equal to 180.degree. divided by 4, or 45.degree.. 
Sandwiched between the squares 12,14, and secured to each, is a web 16 of 
flexible fabric defining a floor for the platform 10. The web 16 defines 
at its perimeter an octagonal star shape so as to span fully the center of 
each square 12,14. 
Further inspection of the platform depicted by FIGS. 1 and 2 will reveal 
that the platform defines eight crotches or boarding stations 18-32. Each 
of the eight boarding stations 18-32 is usable regardless of which face of 
platform 10 is upward. The boarding stations are defined between adjacent 
protruding apexes 34-48 of the squares 12,14. That is, the boarding 
stations 18-32 are defined at obtuse exterior reentrant angles formed in 
plan view by the angular juxtaposition of the respective sides of the 
squares 12,14. Because each square 12,14 has four equal sides, and each is 
relatively rotated 45.degree. with respect to the other, the reentrant 
angles at boarding stations 18-32 are each substantially equal to 
360.degree. divided by the number of sides (4), plus the angle of relative 
rotation (45.degree.) or 135.degree. according to the preferred embodiment 
as disclosed. Each face of the platform 10 further includes a number of 
similarly disposed relatively short straps 50 (only one set of which is 
visible) which define handholds for use by evacuees in boarding the 
platform. Similarly, a single set of relatively longer straps 52 
circumscribes the perimeter of the platform 10. The straps 52 may be used 
both as handholds and stirrups by evacuees boarding the platform. 
Having described the structure of platform 10, attention may now be 
directed to the use of the platform. Consideration of FIG. 1 will 
immediately make clear how able-bodied evacuees may make use of the eight 
boarding stations 18-32. That is, an evacuee at a boarding station may use 
the straps 50 and 52 to haul himself from the sea and partially onto the 
platform 10. From such a position, an evacuee can complete boarding of the 
platform by placing one knee or a foot upon the protruding apex of the 
underlying one of the squares (as illustrated, on square 14) to scramble 
aboard the platform. 
The platform 10 provides particular advantage when injured or otherwise 
disabled evacuees are to be brought aboard the platform. Viewing FIG. 1 
once again, it will be seen that each boarding station 18-32 is bracketed 
between an adjacent pair of the apexes 34-48. Thus, an able-bodied evacuee 
aboard the platform 10 may take a position at one of the protruding apexes 
34-48 in order to assist disabled evacuees from the sea at an adjacent 
boarding station 18-32. Further, a pair of able-bodied evacuees may take 
positions at a pair of adjacent apexes in order to assist disabled 
evacuees to board the platform 10 at the boarding station therebetween. 
For example, a pair of able-bodied evacuees at apexes 34 and 36 may 
together assist a disabled evacuee at boarding station 18 to leave the sea 
and board the platform. 
FIG. 3 and 4 depict an alternative embodiment of the invention wherein 
reference numerals used in FIGS. 1 and 2 and having a prime added indicate 
similar or analogous structure. Flotation platform 10' includes a 
substantially triangular web of fabric 54 which spans an apex of one of 
the open centered squares 12,14. By way of example, web 54 spans a corner 
of square 14'. Web 54 is secured to tubular section 14', as by a seam 56. 
The web 54 is spaced from the floor fabric 16 and includes sufficient 
slack that it may bow downwardly as depicted in FIG. 4. According to a 
preferred embodiment of the invention, a flotation platform as depicted in 
FIG. 1 may further include a web 54 at each inside corner of each of the 
squares 12,14. Thus, irrespective of which face of the platform is upward, 
four of the webs 54 will be on the downward face of the platform to 
receive sea water therein. As seen in FIG. 4, the webs 54, because of 
their slack, define pockets or basins within which sea water may be 
recieved to add ballast weight and stability to the platform 10. 
Conversely, the webs 54 on the upwardly disposed face of the platform 10', 
also because of their slack, may lie limply in the corners of the 
platform. Thus, the webs 54 on the upward face of the platform do not 
interfere with the use of the platform corners by evacuees. 
While the present invention has been depicted, described, and defined by 
reference to particularly preferred embodiments thereof, no limitation 
upon the invention is implied by such reference and none is to be 
inferred. The invention is intended to be limited only by the spirit and 
scope of the appended claims which provide a definition of the invention.