Note: Descriptions are shown in the official language in which they were submitted.
9(~9
~ The invention relates to a floating body for wind-
surfing or surf-boarding which is made of a foamed material
with incorporated reinforcement.
Floating bodies or surf-boards at present being
mardeted are relatively heavy - between 20 and 25 kg. It is
therefore not easy for young or female sports enthusiasts to
carry such a board over long distances or to lift it up to,
or down from, the roof of a car. Conventional surf-boards
or floating bodies also have other disadvantages and attempts
have been made to overcome these by the use of particularly
light designs. A relatively heavy board digs more deeply into
the waves, produces a higher resistance and is therefore
slower and less easy to turn.
Most surf-boards made of thermoplastic half-shells,
and containing polyurethane foam, do not possess absolùtely
watertight joints. This allows water to penetrate into the
foam core, thus making the board still heavier. Sharp edges
on the thermo-plastic sheels may produces injuries when the
user himself falls or when the board itself collides with
other swimmers.
Attempts have therefore already been made to produce
a floating body of the lightest possible weight, to facilitate
transportation on land, and also possessing satisfactory
ridlng properties, which will not absorb water, which is made
of a material which can absorb impacts, and which presents
no danger of injury. The central area, which carries the
weight of the wind-surfer, should possess maximal rigidity
which diminishes towards the ends, thus producing the desired
uniform line of flexure.
According to the present invention, there is
provided a floating body for wind-surfing or surf-boarding
consisting a foamed material with built-in reinforcement,
characterized in that the reinforcement consists of at least
one rib composite structure arranged summetrically of the
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long~tudinal ~xis of the floating body and comprising a core
and reinforcing layers on two of the outer surfaces of the
said rib united with the said core, the cross-section of
the said rib decreasing from the central area of the said
floating body towards the two ends thereof for the purpose
of achieving a distribution of rigidity and strength in-
dependent of the external shape of the said floating body;
and in that the said rib is embedded in a foam-material element
which is enclosed, at least at the upper surface, by a layer
of flexible foamed material constituting the outer skin of
the floating body, the said layer being of greater density
than the foam-material element.
The rib is preferably of rectangular cross-section,
stands on edge in relation to the top and bottom surfaces of
the floating body, and is embedded in the foam-material
element at a distance from the said top and bottom surfaces.
The height of the rib, thus standing on edge, diminishes
from the middle of the length of the floating body towards
both ends. This produces the desired difference in flexibility
over the length of the floating body. Furthermore, this
decrease in cross-section towards the ends leads to an appre-
ciable reduction in weight.
In the case of a rib of composite design, fibre-
glass reinforcing layers, at the top and bottom surfaces of
a core made of structural foam, have been found particularly
satisfactory.
Finally, it is an advantage to design the rib in
such a manner that it is prepared for the base of a mast, a
centre-board box and/or a fin to be secured thereto.
A preferred example of embodiment of the invention
is explained hereinafter in greater detail, in conjunction
with the drawing attached hereto, wherein:
Fig. 1 shows a longitudinal section through the
floating body;
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~ Fig. 2 shows a transverse section through the loating
body.
According to Fig. l, floating body l comprises a rib
3 embedded into a foam-material element 2 and extending over
almost the entire length of the said floating body. As shown
in Fig. 1, this rib diminished in vertical height approximately
from the middle of the length of the towards each end. The
width of rib 3 remains constant throught the length thereof.
It may be gathered from Fig. 2 that preferably one
rib or.ly is fitted in the longitudinal axis of the floating
body. However, it is also possible to use two ribs ~paced
from the said longitudinal axis.
The sharp taper of rib 3 towards each end results
in a weight-saving of 30% as compared with a rib of constant
cross-section. The user stands approximately at the longitu-
dinal centre of the floating body, where the rib must therefore
have its maximal rigidity.
As shown in Fig. 2, rib 3 is of composite design,
consisting of a core 4 to the top and bottom surfaces of
which are secured reinforcing layers 5,6. Core 4 is prefer-
ably made of fibre-glass reinforced polyurethane-resin foam
with fibre-glass laminates as reinforcing layers at the top
and bottom surfaces. A core of this kind 300 cm in length,
2 cm in width, with an average height of 5 cm, and a material-
density of 200 kg/cm3 weighs 600 g. The total weigh of the
rib, including fibre-glass laminates about l mm in thickness,
is slightly more thant 800 g. This rib is embedded on edge
in foam-material element 2, the connection being made by
gluing.
Foam-material element 2 is made of polyethylene
foam or polystyrene foam or polyurethane foam having a
density of between lO and 40 kp/m3.
Secured to element 2 by gluing or welding i~ an
outer skin 7 which is flexible and is also a layer of foam
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mate~ial, but in this case having a density of at least
50 kp/m3, i.e. a higher density than foam-material element
2. This outer skin has the advantage that it is flexible
enough to absorb impacts well and that it is unlikely to
injure the user in the event of a fall.
A floating body made of the above-mentioned
materials, including the rib, weighs about 9 kg and has a
volume of 180 litres, with an average density of 50 kp/m3.
If these values are compared with corresponding values of a
conventional surf-board weighing 23 kg, with a volume of
230 litres and an average density of 100 kp/m3, it will
be seen that the floating body according to the invention has
a 50% bettér capacity-to-weight ration. The weight can be
still further reduced by using a thinner outer skin, making
it possible to produce a floating bo`dy weighing 8 kg.
The special advantage of the floating body described
above is that the user stands upon a water-repellent surface
which, with closed pores, it not completely flat, thus provid-
ing a good hold for the user's feet. In fact, the feet can
sink in to some extent, thus increasing the area of contact.
Since the foamed material acts as a good insulating layer,
the user standing upon it also has a sensation of warmth.
The floating body has a very flat bottom and,
as a wind-surfing board, is an excellent glider. When there
is little wind, it is at a slight disadvantage to other surf-
boards but, as the wind increases in strength, it soon starts`
to glide and then becomes very fast. In the gliding condition,
it may be controlled almost like a water-ski. In riding
over short waves, the resilience of the material has a very
positive effect, and blos are therefore cushioned and damped.
During jumps in surf, the reinforcing rib is more resistant
to fracture than conventional boards, the main advantage
being that the incorporated rib distributes strength and
rigidity independently of the shape of the floating body.
