Abstract:
A method for molding an article having an upper portion, a lower portion, and an insert located between the upper portion and the lower portion, wherein the article is molded as a single, unitary piece with no seams or discontinuities located between the upper portion and the lower portion, includes providing a first semi-rigid membrane removably mounted to a first rigid housing to define a first fluid tight chamber therein, providing a mold plenum defined at least in part by the first semi-rigid membrane removably mounted to the first rigid housing, filling the first fluid tight chamber with a substantially non-compressible backing fluid to support the first semi-rigid membrane during injection of resin, positioning the insert in the mold plenum, providing fibrous reinforcing material within the mold plenum, the fibrous reinforcing material including portions positioned between the first semi-rigid membrane and the insert, the fibrous reinforcing material portions positioned between the first semi-rigid membrane and the insert  being in contact with the insert, injecting resin under pressure into the mold plenum such that the resin envelops the fibrous reinforcing material and the insert, distributing a resulting injection pressure by the backing fluid, and curing the resin by heating the backing fluid to produce the molded article.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of application Ser. No. 12/123,627, filed May 20, 2008, which is a continuation of application Ser. No. 11/561,974, filed Nov. 21, 2006, now U.S. Pat. No. 7,373,896, which is a continuation of application Ser. No. 11/288,646, filed Nov. 28, 2005, now U.S. Pat. No. 7,156,043, which is a continuation of application Ser. No. 10/118,589, filed Apr. 8, 2002, now U.S. Pat. No. 6,994,051, which is a continuation of application Ser. No. 09/664,019, filed Sep. 19, 2000, now U.S. Pat. No. 6,367,406, which claims the benefit of U.S. Provisional Application Ser. No. 60/156,052, filed Sep. 24, 1999, which applications are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to boats. More particularly, the present invention relates to boats having hulls with strengthened by fibrous reinforcing material and to methods for manufacturing such boats. 
       BACKGROUND OF THE INVENTION 
       [0003]    Boat hulls have historically been made of many different types of material such as aluminum, steel or wood. Another common material used in the manufacture of boat hulls is a laminate material made of fiberglass-reinforced resin. 
         [0004]    Open face molds are frequently used to manufacture fiberglass hulls. To make a hull with an open face mold, a layer of gel coat is frequently first applied to the mold. Next, a barrier layer is often applied to the gel coat. Finally a layer of fiberglass-reinforced resin is applied to the barrier layer. When the hull is removed from the mold, the gel coat provides a smooth, aesthetically pleasing outer surface of the hull. The barrier layer prevents the fiberglass from printing or pressing through the gel coat. The fiberglass provides the hull with structural rigidity. Additional rigidity is typically provided to the hull by stringer and flooring structures that are subsequently mounted within the hull. 
         [0005]    Conventional techniques for manufacturing fiberglass boats involve a number of separate, time consuming process steps. What is needed is a more efficient process for manufacturing boats made of fibrous reinforcement material. 
       SUMMARY OF THE INVENTION 
       [0006]    One aspect of the present invention relates to a method for making a boat. The boat includes a port side positioned opposite from a starboard side. The boat also includes a floor and stingers supports positioned within the hull. The method includes providing a insert having two spaced-apart elongated portions interconnected by at least two spaced-apart transverse portions that extend between the elongated portions. The elongated portions are sized and relatively positioned for one of the elongated portions to extend along the port side of the hull and the other of the elongated portions to extend along the starboard side of the hull. The method also includes positioning the insert in a chamber defined between a male mold piece and a female mold piece. The method further includes providing fibrous reinforcing material that surrounds the insert within the chamber. The fibrous reinforcing material includes portions positioned between the male mold piece and the insert, and also includes portions positioned between the female mold piece and the insert. The method further includes transferring resin into the chamber between the male and female mold pieces such that the resin envelops the fibrous reinforcing material, and curing the resin within the chamber. As the resin cures, the resin enveloped fibrous reinforcing material hardens to form the hull, the floor and the support stringers of the boat. 
         [0007]    A variety of advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the invention and together with the description, serve to explain the principles of the invention. A brief description of the drawings is as follows: 
           [0009]      FIG. 1  is a perspective view of a boat constructed in accordance with the principles of the present invention; 
           [0010]      FIG. 2  is a cross-sectional view taken along section line  2 - 2  of  FIG. 1 ; 
           [0011]      FIG. 3  illustrates a male mold piece, a female mold piece and a pre-formed insert adapted to be positioned between the mold pieces 
           [0012]      FIG. 4  is a perspective view of the underside of the male mold piece of  FIG. 3 ; 
           [0013]      FIG. 5  is a schematic cross-sectional view of a resin transfer molding cell suitable for use in practicing the principles of the present invention; and 
           [0014]      FIG. 6  is an exploded view of portions of the male and female mold pieces of  FIG. 5  with fibrous reinforcing material and the pre-formed insert positioned between the mold pieces. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Reference will now be made in detail to exemplary aspects of the present invention that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0016]      FIG. 1  is a perspective view of a boat  20  constructed in accordance with the principles of the present invention. The boat  20  includes a hull  22  including a bow  24  positioned opposite from a stem  26 . A keel  28  extends between the bow  24  and the stem  26 . Chines  30  and strakes  27  (best shown in  FIG. 2 ) are located on port and starboard sides of the hull  22 . The boat  20  also includes a support structure  29  positioned within the hull  22 . The support structure  29  includes a generally planar, horizontal platform or floor  31 . The support structure  29  also includes first and second transverse supports  41  and  42 . The supports  41  and  42  extend widthwise across the hull  22  and are configured for providing structural reinforcement to the hull  22 . The support structure  29  further includes longitudinal stringer supports. For example, the support structure includes port and starboard stringer supports in the form of upright walls  33  that extend along the length of the hull  22  in a direction generally parallel to the keel  28 . The terms “stringer” and “support stringer” are intended to include any type of member that extends lengthwise along the hull  22  to provide longitudinal reinforcement or support to the hull  22 . 
         [0017]    Still referring to  FIG. 1 , the support structure  29  also defines a plurality of internal compartments. For example, the support structure  29  defines a front storage compartment  44  positioned in front of the second transverse support  42 , a middle fuel-tank compartment  46  positioned between the first and second supports  41  and  42 , and a rear engine compartment  48  positioned behind the first support  41 . The upright walls  33  of the support structure  29  define side walls of the compartments  44 ,  46  and  48 . For example, the upright walls  33  shown in  FIG. 2  define side walls of the middle fuel tank compartment  46 . The front and middle compartments  44  and  46  preferably can be covered with removable panels (not shown). 
         [0018]    Still referring to  FIG. 2 , a foam chamber  53  is defined between the support structure  29  and the hull  22 . The foam chamber  53  has a size and shape that corresponds to a pre-formed buoyant insert  90  (shown in  FIG. 3 ). As shown in  FIG. 2 , the foam chamber  53  includes starboard and port regions  55  and  57  positioned on opposite sides of the keel  28 . The starboard and port regions  55  and  57  each have generally triangular cross-sections. The hull  22 , the floor  29  and the upright walls  33  cooperate to define the starboard and port regions  55  and  57  of the chamber  53 . 
         [0019]    In one particular non-limiting embodiment of the hull  22 , the hull has an outer gel coat layer of about 0.024 inches, and intermediate barrier layer of about 0.035 inches, and an inner fiberglass layer of about 0.25-0.375 inches. The barrier layer prevents the fiberglass from pressing through the gel coat. 
         [0020]    The support structure  29  and the hull  22  are preferably formed as a single, unitary or monolithic piece such that no seams or discontinuities are located between the two structures. For example, as shown in  FIG. 2 , adjacent the chines  30  the floor  31  merges with the hull  22  to provide a seamless connection. Similarly, the upright walls  33  (i.e., the longitudinal stringers) preferably merge with the hull  22  to provide a seamless connection. Preferably, no separate fasteners or adhesive are provided at the connection locations. Instead, the hull  22  and the support structure  29  are preferably made of a fiber reinforced plastic material, and the connection locations preferably consist of continuous, uninterrupted thicknesses of the fiber reinforced plastic material. The term “seamless” is intended to mean that the connection locations are provided by continuous, uninterrupted portions of fibrous reinforced plastic material. 
         [0021]    Preferably, the support structure  29  and the hull  22  are simultaneously formed during a forming process such as an injection molding process or a resin transfer molding process. The phrase “resin transfer molding” is intended to include any type of molding process where a fibrous reinforcing material is positioned within a mold into which resin is subsequently introduced. U.S. application Ser. No. 08/715,533 filed on Sep. 18, 1996 and entitled Apparatus For Molding Composite Articles, which is hereby incorporated by reference, discloses an exemplary resin transfer molding process. 
         [0022]    An important aspect of the present invention relates to a resin transfer molding method for making a boat such as the boat  20  of  FIG. 1 . Generally, the method includes placing a pre-formed buoyant insert into a molding chamber. Preferably, the insert is enclosed, covered or surrounded with layers or portions of fibrous reinforcing material. Similarly, at least portions of the mold are lined with fibrous reinforcing material. The method also includes transferring resin into the molding chamber such that the resin envelops the fibrous reinforcing material. By using a pre-formed insert within the mold, the support structure  29  and hull  22  of the boat  20  can be simultaneously molded as a single piece within the molding cavity. 
         [0023]      FIG. 3  shows a mold  50  including a set of male and female mold pieces  52  and  54  suitable for use in manufacturing a boat such as the boat of  FIG. 1 . The male mold piece  52  nests within the female mold piece  54 . The female mold piece  52  has a top surface  56  shaped in the inverse of the bottom side of the boat  20 , and the male mold piece  52  has a bottom surface  58  shaped in the inverse of the top side of the boat  20 .  FIG. 4  shows a schematic/simplified view of the bottom surface  58  of the male mold piece  52 . As shown in  FIG. 4 , the male mold piece  52  includes a front projection  60  that is the inverse of the front storage compartment  44 , a middle projection  62  that is the inverse of the middle-fuel tank compartment, and a rear projection  64  that is the inverse of the rear engine compartment  48 . A first slot or gap  66  corresponding to the first transverse support  41  of the boat  20  is located between the rear projection  64  and the middle projection  62 . A second slot or gap  68  corresponding to the second transverse support  42  of the boat  20  is located between the middle projection  62  and the front projection  60 . Side walls  65  of the projections  60 ,  62  and  64  correspond to the upright walls  33  of the support structure  29  of the boat. A planar surface  63  corresponds to the floor  31  of the support structure  29 . 
         [0024]      FIG. 3  also shows an insert  90  suitable for use in manufacturing the boat of  FIG. 1 . The insert  90  is preferably made of a buoyant material (i.e., capable of floating in water) such as foam. Preferably, the insert  90  is covered, enclosed or otherwise surrounded by a fibrous reinforcing material  91 . The fibrous reinforcing material can be affixed to the insert  90  (e.g., by adhesive) or loosely applied or laid about the insert  90 . 
         [0025]    Preferably, the insert  90  is pre-formed to include first and second spaced-apart elongated portions  92  and  94 . The first elongated portion  92  is sized to extend along the starboard region  55  of the foam chamber  53  of the hull  22 . Similarly, the second elongated portion  94  is sized to extend along the port region  57  of the foam chamber  53  of the hull  22 . Each of the first and second elongated portions  92  and  94  preferably has a generally triangular transverse cross section. The elongated portions  92  and  94  also include inwardly facing surfaces  95  that face one another. The inwardly facing surfaces  95  are aligned in an upright orientation. As shown in  FIG. 2 , the inwardly facing surfaces  95  are configured to extend along the upright walls  33  of the support structure  29  after the boat  20  of  FIG. 1  has been manufactured. Planar top surfaces  97  of the elongated portions  92  and  94  are aligned at right angles with respect to the inwardly facing surfaces  95 . As shown in  FIG. 2 , the top surfaces  97  are positioned beneath the floor  31  after the boat  20  has been manufactured. 
         [0026]    Still referring to  FIG. 3 , the first and second elongated portions  92  and  94  are interconnected by first and second spaced-apart transverse portions  96  and  98  that extend between the inwardly facing surfaces  95  of the elongated portions  92  and  94 . When the boat  20  of  FIG. 1  has been manufactured, the transverse portions  96  and  98  are respectively positioned within the first and second supports  41  and  42  of the boat  20  (i.e., the transverse portions  96  and  98  are encased within a fiber reinforced plastic material to provide the supports  41  and  42 ). As shown in  FIG. 3 , the insert  90  has a two piece construction with the two pieces being interconnected by a tongue and groove type connection. However, in alternative embodiments, it will be appreciated that the insert  90  can be constructed as single piece of buoyant material. 
         [0027]      FIG. 5  illustrates the male and female mold pieces  52  and  54  incorporated within a molding cell  70 . The cell  70  includes a substantially rigid outer support housing  72  having a bottom portion  74  and a removable top portion  76 . The male mold piece  52  is secured to the top portion  76  of the housing  72  and the female mold piece  54  is secured to the bottom portion  74  of the housing  72 . A top fluid chamber  78  is defined between the top portion  76  and the male mold piece  52  and a bottom fluid chamber  80  is defined between the bottom portion  74  and the female mold piece  54 . When the top portion  76  of the housing is mounted on the bottom portion  74  of the housing as shown in  FIG. 5 , a molding chamber  82  is defined between the male mold piece  52  and the female mold piece  54 . 
         [0028]    In the embodiment of  FIG. 5 , the mold pieces  52  and  54  are preferably semi-rigid membranes that are capable of at least slightly flexing when pressurized resin is injected into the mold chamber  82 . In one particular embodiment, the male and female mold pieces  52  and  54  are made of sheets of metal. In other embodiments, the mold pieces  52  and  54  can be made of other materials such as fiberglass, plastic, reinforced nylon, etc. To prevent the mold pieces  52  and  54  from excessively deforming during the molding process, the top and bottom fluid chambers  78  and  80  are preferably filled with a non-compressible liquid such as water. In this regard, the top and bottom fluid chambers  78  and  80  preferably include inlets  73  for filling such chambers  78  and  80  with the non-compressible liquid. The inlets are preferably opened and closed by valves  75 . By filling the top and bottom fluid chambers  78  and  80  with non-compressible liquid and then sealing the chambers  78  and  80 , the liquid retained within the chambers  78  and  80  provides backing support to the mold pieces  52  and  54  such that deformation of the mold pieces  52  and  54  is resisted. 
         [0029]    The cell  70  also includes structure for introducing resin into the molding chamber  82 . For example, as shown in  FIG. 5 , the cell  70  includes an injection sprue  86  that extends through the top portion  76  of the housing  72  for injecting resin into the molding chamber  82 . Preferably, the sprue  86  is placed in fluid communication with a source of resin  88  (e.g., a source of liquid thermoset resin) such that resin can be pumped from the source of resin  88  through the sprue  86  into the molding chamber  82 . While a single sprue  86  has been shown in  FIG. 5 , it will be appreciated that multiple sprues can be provided through both the top and bottom portions  76  and  74  of the support housing  72  to provide uniform resin flow throughout the molding chamber  82 . 
         [0030]    It will be appreciated that the cell  70  can include a variety of additional structures for enhancing the molding process. For example, the cell  70  can include a heating/cooling mechanism for controlling the temperature of the fluid contained in the top and bottom fluid chambers  78  and  80 . Additionally, the top and bottom fluid chambers  78  and  80  can include closeable vents for allowing air to be bled from the fluid chambers  78  and  80  as the fluid chambers are filled with liquid. Furthermore, the molding chamber  82  can include vents for bleeding resin from the molding chamber  82  once the molding chamber  82  has been filled with resin. 
         [0031]    To manufacture a boat using the cell  70 , the cell  70  is opened and the insert  90  of  FIG. 3  is placed within the molding chamber  82 . Preferably, fibrous reinforcing material  91  is provided that surrounds or covers the insert  90 . Preferably, fibrous reinforcing material  91  is also laid below the insert  90  along the top surface  56  of the female mold  54 , and above the insert  90  along the bottom surface  58  of the male mold  52 . For example,  FIG. 6  shows an exploded view of portions of the male and female mold pieces  52  and  54  with a first portion of the fibrous material  91  positioned between the insert  90  and the male mold piece  52 , and a second portion of the fibrous reinforcing material  91  positioned between the insert  90  and the female mold piece  54 . After the insert  90  and fibrous material  91  have been positioned in the cell  70 , the cell  70  is closed such that the insert and the fibrous reinforcing material  91  are enclosed within the molding chamber  82 . Thereafter, resin is injected or otherwise transmitted into the molding chamber  82  through the sprue  86 . 
         [0032]    Prior to the resin injection process, the top and bottom fluid chambers  78  and  80  of the cell  70  are preferably filled with non-compressible liquid. The filled chambers  78  and  80  provide back support to the mold pieces  52  and  54  such that deformation of the mold pieces  52  and  54  during the pressurized resin injection process is resisted. 
         [0033]    When the cell  70  is closed, the transverse portions  96  and  98  of the insert  90  respectively fit within the first and second gaps  66  and  68  defined by the male mold piece  52 . Additionally, the first and second elongated portions  92  and  94  of the insert  90  preferably are respectively positioned along port and starboard sides of the front, middle and rear projections  62 ,  64  and  66  of the male mold piece  52 . Furthermore, the inwardly facing surfaces  95  of the insert  90  oppose the side walls  65  of the projections  60 ,  62  and  64  of the male mold  52 . Moreover, the planar surface  63  of the male mold  52  opposes the planar top surfaces  97  of the insert  90 . 
         [0034]    After the cell  70  has been closed and the backing chambers  78  and  80  have been filled with fluid, the resin is injected or otherwise transferred into the mold chamber  82 . As the resin enters the mold chamber  82 , the resin envelops and impregnates the reinforcing material  91  contained within the mold chamber  82 . Once the molding chamber  82  has been filled with resin, the resin within the chamber  82  is allowed to cure within the cell  70 . As the resin cures, the resin enveloped fibrous reinforcing material hardens to form the support structure  29  and the hull  22  of the boat of  FIG. 1 . For example, resin enveloped fibrous material  91  positioned along the top surface  56  of the female mold  54  hardens to form the hull  22 . Also, resin enveloped fibrous reinforcing material positioned between the inwardly facing surfaces  95  of the insert  90  and the side walls  65  of the projections  60 ,  62  and  64  of the male mold  52  forms the upright side walls  33  of the support structure  29 . Additionally, resin enveloped fibrous reinforcing material positioned between the planar surface  63  of the male mold  52  and the planar top surfaces  97  of the insert  90  form the floor  31  of the support structure  29 . Moreover, resin enveloped fibrous reinforcing material surrounding the transverse portions  96  and  98  of the insert  90  form the first and second supports  41  and  42  of the support structure  29 . 
         [0035]    By practicing the above described method, the support structure  29  and hull  22  can be simultaneously formed as a single seamless piece within the molding chamber  82 . By forming the hull and support structure  29  as a single piece, numerous process steps typically required by prior art manufacturing techniques can be eliminated thereby greatly enhancing manufacturing efficiency. 
         [0036]    To enhance the aesthetic appearance of the boat, the male and female mold pieces  52  and  54  are preferably coated with a layer of gel coat prior to enclosing the insert  90  and the fibrous reinforcing material  91  within the cell  70 . Additionally, barrier coat layers are also preferably provided over the layers of gel coat for preventing the fibrous reinforcing material  91  from printing or pressing through the gel coat layers. An exemplary barrier coat layer is a layer of vinyl ester having a thickness of about 0.025 inches. Commonly, the gel coat layers can each have a thickness of about 0.020-0.024 inches. 
         [0037]    It will be appreciated that additional structures/reinforcements can also be placed within the molding chamber  82  prior to injecting resin therein. For example, reinforcements such as plates for mounting seats, engine mount supports, and other reinforcements conventionally used in the boat manufacturing industry can be positioned at predetermined locations within the holding chamber prior to injecting resin therein. Preferably, the reinforcements are attached to the pre-formed insert  90  and positioned within the mold during the molding process. However, the reinforcements can be also be attached to the boat  20  after the hull  22  and the support structure  29  have been molded. This type of post-mold attachment procedure will typically involve milling certain locations of the boat  20  to facilitate mounting the reinforcements. 
         [0038]    As shown in  FIG. 3 , the insert  90  is covered with a fibrous reinforcing material affixed to the insert  90  before the insert  90  has been placed in the cell  70 . It will be appreciated that in alternative embodiments, the insert  90  can covered with fibrous reinforcing material by placing or laying the fibrous reinforcing material about the various features of the insert  90  within the cell  70 . Also, it will be appreciated that the various material thicknesses shown in  FIG. 6  are diagrammatic (i.e., not to scale), and that in actual practice the material thicknesses can be varied at different locations within the cell to provide the resultant boat with desired strength characteristics. For example, in certain embodiments, a thicker layer of fibrous reinforcing material can be used for the portion of the hull  22  located below the water line (i.e., below the chines  30 ) as compared to the portion of the hull  22  above the water line. Similarly, the thickness of fibrous reinforcing material can also be varied for the various components of the support structure  29 . 
         [0039]    While any number of different types of resins could be used in practicing the present invention, a preferred thermoset resin is a blended polyester resin sold by Reichold Manufacturing. Additionally, the fibrous reinforcing material can include any number of different types of material such as glass, graphite, aramid, etc. Furthermore, the fibrous reinforcing material can have a chopped configuration, a continuous configuration, a sheet configuration, a random configuration, a layered configuration or an oriented configuration. 
         [0040]    With regard to the foregoing description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size and arrangement of the parts without departing from the scope of the present invention. For example, it will be appreciated that the various aspects of the present invention apply to resin transfer molding techniques that utilize rigid molds as well as semi-rigid molds. It is intended that the specification and depicted aspects be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the following claims.