Floating barrier

The invention relates to an elongated floating barrier for use in controlling and concentrating substances floating on a liquid surface, preferably oil floating on a water surface. The barrier comprises a front shield towards the front surface (2) of which the substances are deposited and transported sideways along the shield as the barrier is moved relative the liquid surface. The front shield is inclined in such a way that its upper edge (5) is abaft its lower edge (6) and a towing means (4) is attached to the lower edge of the shield and arranged to give a mainly horizontal pull in the barrier when it is moved relative the water surface. The deep-going of the front shield and its inclination relative the water surface are regulated by a buoyant member (7), which is extended along the back (3) of the front shield and the lower face (8) of which is connected with the lower edge (6) of the front shield and extended in a backward upward direction so that it intersects the water surface when the barrier is in operational position.

This invention relates to an elongated, floating barrier for use in 
controlling substances floating on a liquid surface, preferably oil 
floating on a water surface. More particularly the invention relates to a 
barrier of the type comprising a front shield, towards the front surface 
of which the substances are deposited and transported sideways along the 
shield as the barrier is moved relative the liquid surface. Such barriers 
are above all used for directing and aggregating oil on a water surface to 
a more concentrated string which can afterwards be taken care of by other 
means. Usually the barrier is towed through the water somewhat inclined 
relative the towing direction, but it can also e.g. be anchored in a 
stream. 
A disadvantage with previously known barriers of this type is that they 
admit only a low relative speed between barrier and water surface, in most 
cases only 1-2 knots, before over- or underflow of the floating substances 
occurs and stability problems arise. Because the barrier is subjected to a 
liquid flow towards a relatively large front area, the load on the barrier 
is very big and uncontrolled oscillatory and rotatory movements easily 
occur. Different attempts have been made to stabilize the movement of a 
barrier in tow, but have only resulted in a marginal increase of the 
possible towing speed and often caused the construction to be bulky and 
difficult to transport and handle. 
An object of the present invention is to provide a floating barrier by 
which the above mentioned disadvantages of previously known barriers are 
eliminated. Thus, according to the invention a barrier is provided, which 
has a new profile of special shape admitting a considerably higher 
relative speed between barrier and liquid surface that has previously been 
possible. 
A further object of the invention is to provide a barrier, for which the 
depth and inclination relative the liquid surface are automatically 
regulated by the current relative speed between barrier and liquid 
surface, in order to obtain a stable operational position for every speed. 
The effectiveness of the barrier is hereby increased and the risk for 
over- or underflow is reduced. 
A further object of the invention is to obtain a barrier, which in spite of 
a relatively complex, hydrodynamically designed profile, can be coiled 
into a compact transport form and which can be taken into action quickly 
and easily. 
These and other objects and advantages, which will become apparent from the 
following description, are accomplished by the invention defined in the 
claims.

FIGS. 1 and 2 illustrate according to the invention an elongated floating 
barrier, which is illustrated in operational position, i.e. when a 
relative speed exists between barrier and liquid. The barrier comprises a 
front shield 1 having a front side 2, a back side 3, an upper edge 5 and a 
lower edge 6. In operation, the front shield has an upright position with 
its lower edge 6 under the liquid surface and its upper edge 5 above the 
liquid surface and is inclined in a backward direction so that its upper 
edge 5 is abaft its lower edge 6. When the barrier is moved relative the 
liquid surface facing the direction of movement at an oblique angle, 
substances floating in the liquid are deposited towards the front side of 
the front shield and transported sideways along the shield. A towing means 
4 is attached to the lower edge 6 and arranged to give a mainly horizontal 
pull in said edge 6 when the barrier is moved relative the liquid surface. 
Further, the barrier has a body forming member extending along the 
backside 3 of the front shield and being arranged to regulate the depth 
and the inclination of the front shield at said movement of the barrier. 
The body forming member has an upper face 9 connected with the upper part 
of the front shield and a lower face 8 connected with the lower edge 6 of 
the front shield and forms between said faces and said front shield a 
buoyant body 7. The body forming member is extended in a backward 
direction from the front shield so the lower face 8 thereof will intersect 
the liquid surface when the barrier is in operational position. 
The barrier can be used in a number of different occasions for controlling 
solid or liquid substances on a liquid surface, but is primarily intended 
for use in the guiding and concentration of oil on a water surface. In the 
following description the invention will for the sake of simplicity be 
described in connection with this latter use, which should not be 
interpreted as limitative for the invention. 
The towing means 4 is adapted to give a mainly horizontally directed pull 
attacking in the lower edge 6 of the front shield. The towing means 4 may 
consist of a cable attached to the lower edge 6 of the front shield 
throughout the length of the barrier or have the design shown in FIG. 1 or 
2, comprising a primary cable 10 situated at a distance ahead of the 
barrier and connected with the lower edge 6 of the front shield by 
secondary cables. Each end of the primary cable may in its turn be 
connected to a tug or other towing device or be anchored when the barrier 
is located in a flowing water. It is also possible to connect only one end 
of the primary cable with a tub and to connect the other end with a 
pulling board, which pulls the barrier out in a certain angle relative the 
course of the towing boat. 
The shape of the barrier makes the center of gravity always is behind the 
front shield and above the lower edge 6 of the front shield. When the 
barrier is towed through the water by a pull attacking in the lower edge 
of the front shield, the front shield will cut in a somewhat downward 
direction into the water and tend to tip backwards. This is however 
counteracted by the backwardly extending buoyant body 7, which will lift 
the steam of the barrier and thereby regulate the inclination of the front 
shield relative the water surface. Thus the length of the buoyant body in 
the backward direction is conformed to the size and shape of the front 
shield. Generally the buoyant element has a length in the water-line 
overstepping the deep-going of the barrier. As the front shield in this 
way is prevented from tipping backwards, the barrier is pressed deeper 
into the water until a position of equilibrium is reached owing to the 
simultaneously increasing displacement of the buoyant element 7. It is 
preferred that the front shield has a concave front side in such a way 
that its lower edge 6 together with the lower face 8 of the body forming 
member form a relatively acute angle, which will facilitate the water 
cutting function of the front shield. As a result of the fact that the 
lower face 8 of the body forming member is connected to the lower edge 6 
of the front shield and extended backwards upwards until it interects the 
water surface, a gradual increase of the displacement is achieved for 
every increase of the depth. A stable working position will automatically 
be established for every relative speed between the barrier and the water 
surface. 
Further to this design, it is avoided that whirling and suction effects 
occur behind the lower edge 6 of the front shield. Such a whirl formation 
promotes an escape flow beneath the barrier, which is consequently avoided 
with a barrier according to the invention. 
These conditions make it possible to use the barrier at a considerably 
higher relative speed between the barrier and the water surface than what 
has been possible with previously known barriers. Tests have e.g. proved 
that a barrier having the profile shown in FIG. 2, can be towed at a speed 
of 5.6 knots with a maintained stable operational position in the water. 
The embodiments shown in FIGS. 1-3 have a triangular-like cross section, 
which is the most rational and preferred shape. Because the stern is 
extended into a pointed edge, favourable hydrodynamic properties and an 
insignificant whirl formation behind the barrier will be obtained, 
resulting in a low towing resistance. Also the influence of the wind on 
the barrier will become small when the profile has this shape. Other cross 
sectional forms may be used. Particularly the upper face 9 of the body 
forming member can be varied. E.g. the front shield can be extended above 
the upper connection between the upper face 9 and the front shield or an 
extra overflow protection may be arranged as a stand-up part at the upper 
edge of the front shield. 
Besides, there is no absolute requirement that the buoyant body has to be a 
closed volume as shown in the figures, even if this is preferred with 
regard to surge etc which might occasionally wash the barrier. 
As the barrier primarily is intended for taking care of oil spills at sea 
and on lakes, it is important that it can be given a favourable format 
from transport point of view and quickly and easily by taken into use from 
its transport condition. According to a preferred embodiment of the 
invention the barrier is thereof made collapsible. The buoyant body of the 
barrier is thereby filled with gas, preferably air, which can be let out 
and the barrier deflated to a mainly flat and coilable form. 
The buoyant body of the barrier can be inflated by means of a pump or a gas 
cylinder so as to keep it extended by an internal pressure above 
atmospheric. An airfilled body can however also be obtained without using 
pressure above atmospheric, whereby expander means are arranged to expand 
the barrier from its collapsed condition mechanically by spring action at 
the same time as air is sucked into the barrier through special valve. 
Expander means of this type are previously known in the literature and are 
described in e.g. U.S. Pat. No. 3, 686,869; U.S. Pat. No. 3,798,911; U.S. 
Pat. No. 4,068,478 and U.S. Pat. No. 4,295,755. 
Illustrated in FIGS. 3 a-c are cross sections of an embodiment of a barrier 
having a specially designed expander means according to the present 
invention. Different phases of the collapsing of the barrier are 
illustrated in the FIGS. 3 a-c. The expander means 12 comprises a 
substantially parallelogram-shaped frame construction, the sidemembers of 
which are foldable in the corners so that the shape of the frame can be 
altered, and a spring 13 being arranged between two opposite corners of 
the frame. The expander means co-operates with ribbonlike stiffening 
elements 14 and 25 at the expanding resp. compression of the profile of 
the barrier. A number of co-operating expander means and stiffening 
elements of this type are located with a certain space between them along 
the length of the barrier. The stiffening element comprises a 
bottom-stiffener 15 extending from the front edge to the rear edge of the 
barrier along the lower face 8 of the body forming member, and a front 
shield stiffener 15 extending along the front shield from the upper edge 
to the lower edge thereof. The frame construction of the expander means 
has one corner attached to the bottom stiffener 14 and the opposite corner 
attached to the upper part of the front shield stiffener 15 and the spring 
13 being arranged between the remaining two corners 16 and 17. 
The barrier can be made in a conventional manner from impervious rubber 
cloth of the like and may e.g. be designed as interconnectable units and 
be divided into sections by partition walls. The frames of the expander 
members and the stiffening elements can be made from strips of a 
relatively stiff plastic material that permits a certain bending. 
When taken into operation the barrier is transported to the place of use, 
preferably in a coiled condition, where it is uncoiled into the water at 
same time as it is filled with air. When the barrier has expander means as 
shown in FIG. 3, the barrier is expanded automatically when the 
compressing force expires by the very act of uncoiling the barrier. In 
doing so the spring 13 pulls the foldable corners 16 and 17 towards each 
other and the frame construction lifts the front shield stiffener as shown 
in FIG. 3 b. Air is simultaneously sucked into the barrier though valves 
(not shown). The barrier is in this way expanded to the fully extended 
shape shown in FIG. 3 a. Reference numeral 9 designates the upper face of 
the body forming member, which in this connection is stretched and works 
as a stop for the expander means. It is for this purpose however also 
possible to have a separate, flexible band that is correspondingly 
stretched and works as a stop for the expander means. 
Oil floating on the water surface is thereafter concentrated by towing the 
barrier by the towing means 4, facing the direction of movement at an 
oblique angle. Generally the barrier is towed at an angle of 20-30 degrees 
relative the towing direction. The relative movement between the barrier 
and the water causes the front shield to cut downwards into the water and 
the previously described regulation of the depth and the inclination of 
the front shield relative the water surface occurs. The barrier will 
thereby take its operational position as shown in FIG. 2. The oil is 
deposited towards the front shield and transported sideways along the 
shield and left as a concentrated string in the water. The oil-string is 
taken care of by a following oil collecting boat or the like. As mentioned 
earlier the barrier can also be anchored in a flowing water and in a 
similar way be arranged to guide and concentrate oil and other substrates 
floating on the water. 
The barrier can also be used in other connections where it is desirable to 
guide and concentrate solid or liquid substances floating on a liquid 
surface. E.g. the barrier can be mounted in a basin or the like.