Concrete marine float and method of fabricating same

A marine float for use in conjunction with a concrete floating dock system and methods for manufacturing the same. The float consisting of a buoyant core of expanded polystyrene foam supporting a textured deck of standard aggregate concrete and surrounded by a shell of fiberglass reinforced cement. The float is fabricated as a unitary whole by pouring a layer of standard aggregate concrete in a form over a texturing mat to provide the textured deck, placing a buoyant element over the poured deck and spraying a layer of fiberglass reinforced cement around the buoyant element before any of the concrete elements has set. All concrete elements are then permitted to set to form a monolithic float.

BACKGROUND OF THE INVENTION 
The present invention relates to a marine float for use in conjunction with 
a glass fiber reinforced concrete floating dock system wherein a plurality 
of floats may be attached to one another and arranged in any desired 
configuration, and a method of fabricating the floats. 
It has been known to utilize concrete in the manufacture of marine docks. 
Typically, the concrete docks of the prior art consisted of a plurality of 
generally rectangular concrete floats which were secured to one another to 
achieve a desired configuration for the dock. The floats generally 
consisted of a rather thick poured concrete shell surrounding a buoyant 
element that was either hollow or constructed of some buoyant material 
such as expanded polystyrene (earlier floats were hollow in concrete 
floating docks). The methods of attaching successive floats to one another 
vary. Such prior art dock system are, for example, described in U.S. Pat. 
Nos. 4,265,193, 4,318,361 and 3,779,192. 
Use of concrete enhances the durability of the docks as concrete is less 
suspeptible to the adverse effects of water, salinity and wave action than 
traditional dock materials such as wood, and provides improved strength 
characteristics. The poured, standard aggregate concrete used in the docks 
of the prior art presented certain disadvantage in that it lacked adequate 
flexibility which is advantageous under the conditions of alternating 
stress imparted by wave action and in that its bulk and weight made it 
difficult to store and transport such docks. 
The methods typically used to manufacture the concrete docks of the prior 
art involved the use of a form or mold into which concrete was poured to a 
predetermined height. The floating or buoyant portion of the dock section 
was then placed in the form and concrete poured around and on top of the 
buoyant portion to complete the float. This method of construction had 
drawbacks in that the process was extremely slow and required a good deal 
of time for the concrete of the dock to set and is therefore 
costintensive. Furthermore, manufacturing cost of molds are substantial 
and the method of constructions is restrictive in that it does not allow 
any flexibility in shape, size, and buoyancy of the float without changing 
the molds. 
SUMMARY OF THE INVENTION 
The concrete float of the present invention avoids many of the problems 
inherent in the concrete of the prior art. It is one object of the present 
invention to provide a float for use in conjunction with a concrete dock 
system having a fiberglass reinforced concrete shell that is relatively 
thin, but that retains the strength and durability generally associated 
with the concrete docks of the prior art. 
It is another object of the invention to provide a marine float for use in 
conjunction with concrete docks that may be produced by a method allowing 
for production flexibility to enable the manufacturer of said float to 
vary buoyancy on individual floats without necessitating a change of 
molds. 
It is another object of the invention to provide a marine float for use in 
conjunction with concrete docks that has reduced weight and bulk 
characteristics yet retains the strength of the concrete docks of the 
prior art. 
It is another object of the present invention to provide a marine float for 
use in conjunction with a concrete dock having improved stability 
characteristics by providing pontoons associated with the buoyant element 
of the float. 
It is a further object of the present invention to provide a marine float 
for use in conjunction with a concrete dock having a textured, poured 
concrete deck supported by a buoyant portion of expanded polystyrene 
covered with a relatively thin shell of fiberglass reinforced concrete. 
The improved method for manufacturing the marine float of the present 
invention generally comprises the steps of providing a rectangular form or 
mold designed to create a textured deck surface, spraying a layer of glass 
fiber reinforced concrete into the form to a predetermined depth, thereby 
forming a deck, pouring a layer of fine aggregate concrete on the sprayed 
layer of glass fiber reinforced concrete; placing a buoyant element upon 
the unset cement of the deck; and overlying a layer of fiberglass 
reinforced concrete; applying a layer or shell of fiberglass reinforced 
concrete around the buoyant element by spraying; allowing the concrete to 
set; and finally removing the form.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawing, wherein like numerals represent like elements 
throughout the several views, the present invention relates to a concrete 
marine float for use in a marine dock system wherein a plurality of floats 
may be detachably interconnected and secured to one another to form a dock 
having any desired configuration. FIG. 1 illustrates a portion of such a 
system. The dock 10 comprises a plurality of interconnected floats 11. The 
floats may be interconnected in any known fashion. In FIG. 1 successive 
floats are secured to one another by wooden wales 12 attached to the 
exterior sides of the floats 11 by means of a plurality of through-bolts 
13 shown in the dashed lines. The through-bolts are threaded on one or 
both ends so that the wales may be secured by tightening the through-bolts 
with threadably mounted nuts to hold the wales 12 securely against the 
floats 11. Each wale 12 extends from one float 11 to an adjacent float 11 
to thereby interconnect the respective floats. It is advantageous to use 
wooden wales so as to act as a bumper to absorb and cushion collisions 
between the dock and boats. 
Another means for detachably interconnecting the floats 11 may be provided 
such as tensioning cable or bolt (not shown) extending through a central, 
longitudinal passage or void in the floats 11. When the cable is tensioned 
or the bolt tightened, the floats will be secured to one another. In 
addition, the aforedescribed means of detachably interconnecting the 
floats 11 may be used in conjunction with one another. 
Once the dock 10 has been constructed in the desired configuration, it may 
be anchored to a piling 14, shown in FIG. 1. The dock 10 is thereby 
adaptable to rise and fall with the tide. The dock is provided with a 
collar assembly 15 of any suitable configuration which contains a bracket 
16 for receiving therethrough the piling 14. Rollers 17 are interposed 
between the legs of the bracket 16 and the piling 14 to accommodate the 
relative motion of the piling 14 with respect to the bracket 16 and thus 
the dock 10. 
FIGS. 2 and 3 illustrate a float 11 constructed in accordance with the 
present invention. Generally, each float 11 comprises a top or deck 18 of 
sprayed glass fiber reinforced concrete supported by a fine aggregate 
concrete and upon a buoyant element 19 which is covered with a shell 20 of 
fiberglass reinforced concrete. The deck 11 has a plurality of transverse 
concrete reinforcing ribs 21 formed integrally with it. Each of the 
reinforcing ribs 21 has a centrally located, longitudinally extending bore 
or void 22 formed within it for the location of the through-bolts 
extending between the respective sides of the float 11 for the attachment 
of wales 12 in the manner described above. The buoyant element 19 may also 
have a longitudinally extending bore or void 23, shown in FIG. 3. 
Referring to FIG. 3, the buoyant element 19 tapers slightly in the 
direction of the deck 18 and terminates in two pontoon portions 24 which 
define a centrally located, longitudinally extending channel 25 disposed 
in the bottom of the buoyant element. The stability of the float 11 under 
wave action is enhanced by configuring the pontoons 24 in this fashion. 
The shell 20 is advantageously composed of a fiberglass reinforced 
concrete. Fiberglass reinforced concrete provides a shell of superior 
strength and flexibility with relatively low weight that can be applied in 
a relatively thin layer using a spraying process. A preferred type of 
fiberglass reinforced concrete includes a standard liquid mixture of 
concrete into which there is uniformly admixed a predetermined quantity of 
chopped glass fibers. It has been found that a polymer modified fiberglass 
reinforced concrete using alkaline resistant glass fibers provides 
increased durability and weather resistance under extreme conditions of 
moisture and salinity in the environment in which the docks are used. 
THE MANUFACTURING PROCESS 
The specific construction features of the present invention are perhaps 
best described by describing the process by which the floats 11 are 
constructed. The marine float 11 according to the present invention is 
constructed so as to form a monolithic float. All of the steps in the 
manufacturing process are performed while the various concrete elements 
remain encased in plastic and before they have set. By constructing the 
float in this fashion the concrete elements will set as a unitary whole. 
A form (not shown) is provided having a bottom and sides arranged in a 
generally rectangular configuration. The actual size and dimensions may be 
varied to meet the desired design requirements of any particular dock 
configuration. A plasticized polyvinyl chloride texturing mat is placed in 
the bottom of the form in a second manufacturing step. The texturing mat 
serves as a means for imparting a given textured surface to the deck 18 of 
the float 11. For instance, if it is desired that the deck have a 
simulated wood surface, a texturing mat having reverse surface 
characteristics will be used as a mold or press to impart a simulated wood 
surface to the concrete poured into the form. 
The manner of constructing the float according to the present invention 
begins with the deck 18 and proceeds through the bottom of the float 11 by 
building upon the deck 18 while the float 11 is in an inverted position. A 
layer of glass fiber reinforced concrete is sprayed into the form over the 
plasticized polyvinyl chloride mat to a predetermined depth to form the 
deck 18. Generally, this will be on the order of three-fourth inch depth. 
As previously indicated a polymer modified fiberglass reinforced concrete 
containing alkaline resistant glass fiber has proven to be well suited for 
this purpose. The concrete used for the deck may be integrally colored to 
conform to the type of textured surface being used for aesthetic purposes. 
Using the previous example of a simulated wood surface, the color chosen 
would advantageously impart to the deck a color of wood. 
Before the glass fiber reinforced concrete of the deck has set and while it 
is still in a semi-liquid or plastic state, a layer of standard aggregate 
concrete 28 is applied on top of the layer forming the deck 18 by a 
pouring process to a predetermined, uniform depth. This depth will 
typically be on the order of one-half of an inch. 
A plurality of expanded polystyrene blocks 26 are then placed on top of the 
layer of standard aggregate concrete 28 transversely of the float and 
uniformly distributed across the surface. These blocks are preferably made 
of closed-cell block expanded polystyrene with a unit weight of 1.1 pounds 
per cubic foot. The blocks 26 are best illustrated in FIG. 2. The blocks 
26 have a length substantially equal to the width of the form so that they 
will completely span the width of the float when the float has been 
constructed. The placement and size of the blocks are such that a space is 
created between successive blocks 26. A pipe or conduit (not shown) 
extending the entire length of the space between the blocks 26 and 
supported therein above the layer of standard aggregate concrete 28 in the 
sense of the pouring and spraying direction by means associated with the 
form is placed in one or more of said spaces and extends exteriorly of the 
form. The spaces between the blocks 26 are then filled with standard 
aggregate concrete to the level of the blocks 26. Thus it will be seen 
that transversely extending concrete reinforcing ribs 21 are created which 
have longitudinally extending tubes or bores 22 defined by the pipes. In 
the preferred embodiment, once the concrete of the reinforcing ribs 21 
have set sufficiently to maintain the shape of the bore 22, the pipe or 
conduit will be removed to leave a passage through which through-bolts 13 
may be located to secure the wales 12 to the sides of the float 11. 
Alternately, the pipe or conduit may be left in the reinforcing ribs 21. 
A main buoyant member 27, preferably a large block of expanded polystyrene, 
is then positioned on top of the surface defined by the blocks 26 and the 
concrete reinforcing ribs 21. The main buoyant member 27 is essentially 
rectangular having a first surface essentially the same dimensions as the 
deck 18 and a second opposite surface of slightly smaller dimensions such 
that the float 11 will taper in a direction opposite of the deck 18. Main 
buoyant members and pontoons are of one piece and are cut to shape. 
Pontoon portions 24 are then placed on the main buoyant member 27. The 
pontoon portions 24 are also advantageously formed of polystyrene and 
extend longitudinally of the float 11 along the outer edge of the second 
surface of the main buoyant member 27 to form a continuous side wall. The 
pontoon portions 24 have a width of somewhat less than 1/2 of the width of 
the second surface of the main buoyant member 27 to thereby define a 
centrally located longitudinally extending groove or channel 25 in what is 
the bottom portion of the float 11 (see FIG. 3). Providing pontoon 
portions 24 in this fashion enhances the stability of the float under wave 
action. The pontoon portions 24 are also tapered in a direction oppositely 
of the deck so that the float 11 will have a uniform taper along its side 
walls and a trapezoidally shaped central longitudinal channel. 
A layer of fiberglass reinforced concrete is then applied by spraying 
around the sides and bottom of the float 11 to provide a shell 20 
surrounding the buoyant portion 19 of the float 11 and portions 28 and 
layers 18 and 28. The process is completed while all concrete portions are 
still plastic and unset. Upon setting of the concrete, a unitary, 
monolithic float 11 will have been formed and the forms may be removed. 
The deck 18 and the fiberglass reinforced cement shell 20 will cooperate 
to enclose the other elements in concrete. 
Although a limited number of embodiments of the invention have been 
illustrated in the accompanying drawings and described in the foregoing 
specification, it is to be especially understood that various changes, 
such as in the relative dimensions of the parts, materials used, and the 
like, as well as the suggested manner of use of the apparatus of the 
invention, may be made therein without departing from the spirit and scope 
of the invention, as will now be apparent to those skilled in the art.