Abstract:
A retractable mast for sailboats. The mast, which retracts telescopically, comprises an inner core containing air sealed air chambers, either separated or coextensive, which are pressurized when the mast is fully extended. A compressed air bottle or air compressor driven by the boat engine supplies pressurized air to raise the mast. Valves control the pressure release for extension or retraction. The mast may also be operated hydraulically or by stored or generated pressurized gas. The air chambers may contain inflatable bags to retain the pressurized air in each chamber. A stiffener may be erected adjacent the fully extended mast to maintain it in the fully extended position. The stiffener also holds rings which travel along its length for holding the main sail when hoisted. A bracket mounts to the mast and extends around the stiffener, providing for rotatably mounting the boom aft of the stiffener.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/279,668, filed Mar. 30, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to sailboat standing rigging, and, more particularly, to retractable masts for sailboats.  
           [0004]    2. Description of Related Art  
           [0005]    Retractable masts for sail boats are desirable, particularly when the mast must be otherwise stepped for passing under a low bridge, for transport on a trailer, or for storage. Previous retractable masts have complicated mechanical components which are subject to corrosion or breakage, or require hydraulic or fluid seals between nested portions or lengths which require close tolerances and have seals which are subject to wear and eventual leakage.  
           [0006]    U.S. Pat. No. 6,000,354, issued Dec. 14, 2000, to Vanlerberghe describes a retractable mast employing mechanical parts and lines and may be deployed only in a fully extended or fully retracted position. The device of the &#39;354 patent is subject to wear and corrosion and line breakage.  
           [0007]    U.S. Pat. No. 4,718,370, issued Jan. 12, 1988, to Portell-Vila describes a mechanically extendable and retractable mast. The device of the &#39;370 patent is subject to wear and corrosion in a marine environment and the crank mechanism would be an encumbrance on a boat having a head sail.  
           [0008]    U.S. Pat. No. 4,525,999, issued Jul. 2, 1985, to Inman describes a pneumatically operated boom or actuator, extended by the pressure of gasses generated internally by a gas generator. The device of the &#39;999 patent is for a single permanent deployment and thus is not appropriate for a retractable sailboat mast.  
           [0009]    U.S. Pat. No. 4,016,823, issued Apr. 12, 1977 to Davis describes a retractable mast having nested portions locked in an extended state by detents and manually operated. The device of the &#39;823 patent would be practical only for relatively small masts and is limited to discreet lengths of extension.  
           [0010]    U.S. Pat. No. 3,658,189, issued Apr. 25, 1972, to Brown et al. describes a hydraulically operated extendable and retractable boom for use in a vehicle mounted lift using independent hydraulic actuators for each boom section. The device of the &#39;189 patent is complicated and expensive and would be too heavy for use as a mast on a sailboat, as well as subject to corrosion in a marine environment.  
           [0011]    U.S. Pat. No. 2,595,307, issued May 6, 1952, to Selberg describes a hydraulically operated retractable boom or ram for use on a vehicle. The device of the &#39;307 patent requires close tolerances and seals which are subject to corrosion and subsequent, leakage in a marine environment.  
           [0012]    None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention is a retractable mast for sailboats. The mast, which retracts telescopically, comprises an inner core containing sealed air chambers which are pressurized when the mast is fully extended. The chamber may contain bags for holding the pressurized air. An air compressor, which may be powered by the boat engine, is utilized to supply pressurized air. A pressurized air bottle may, also, provide pressurized air. Valves control the pressure release for extension or retraction. The mast may also be operated hydraulically or by stored or generated pressurized gas.  
           [0014]    Accordingly, it is a principal object of the invention to provide a retractable and extendable mast for use on sailboats.  
           [0015]    It is another object of the invention to provide a mast as above having multiple sections which nest together in the fully retracted state and telescope upward upon extension.  
           [0016]    It is a further object of the invention to provide a mast as above which contains one or more sealed air chambers within the interior of the mast, which is attached to a source of pressurized fluid which, upon entrance to the sealed air chamber, inflates the chamber, thus extending upper portions of the mast upward.  
           [0017]    It is yet another object of the invention to provide a mast as above which contains one or more bags within the interior of the mast, which are attached to a source of pressurized fluid which, upon entrance to the bag, inflates the bag, thus extending upper portions of the mast upward.  
           [0018]    Still another object of the invention is to provide a mast which has seals between nested movable mast sections so as to provide an open mast interior which is raised or lowered through control of pneumatic or hydraulic pressure.  
           [0019]    Yet another object of the invention to provide a mast as above wherein each movable mast section has a lower end plate having orifices therethrough so as to control the rate of deployment of the nested mast section.  
           [0020]    Still another object of the invention is to provide a mast as above which has valves to release the pressurized fluid, allowing the bags to deflate and the upper portions of the mast to retract into the lower portion.  
           [0021]    It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.  
           [0022]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    [0023]FIG. 1 is a diagrammatical, environmental, elevational view of a retractable mast for sailboats according to the present invention.  
         [0024]    [0024]FIG. 2 is a diagrammatical, environmental elevational view similar to FIG. 1 with portions of the mast portions and boot broken away.  
         [0025]    [0025]FIG. 3 is a section view drawn along lines  3 - 3  of FIG. 1.  
         [0026]    [0026]FIG. 4 is a diagrammatical, elevational view of the retractable mast of FIG. 1 in the retracted position.  
         [0027]    [0027]FIG. 5 is a section view drawn along lines  5 - 5  of FIG. 4.  
         [0028]    [0028]FIG. 6 is a modified section view similar to FIG. 5, illustrating another embodiment of the invention.  
         [0029]    [0029]FIG. 7A is a view in elevation of an embodiment of the invention illustrating rigging components and a pressure air delivery system.  
         [0030]    [0030]FIG. 7B is a view in elevation similar to that of FIG. 7 illustrating the installation of a sail, a boom, and a stiffener rod, with air pressure provided by an engine-driven compressor.  
         [0031]    [0031]FIG. 7C is a plan view of the boom of FIG. 7B, illustrating the mast mounting bracket, stiffener rod, and boom.  
         [0032]    Similar reference characters denote corresponding features consistently throughout the attached drawings. Figures are not necessarily drawn to scale, but are for illustrative purposes only. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    The present invention is a retractable mast for sail boats which is useful when the mast must be otherwise stepped for passing under a low bridge, for transport on a trailer, or for storage. Previous retractable masts have complicated mechanical component which are subject to corrosion or breakage, or require hydraulic or fluid seals between nested portions or lengths which require close tolerances and have seals which are subject to wear and eventual leakage.  
         [0034]    The present invention employs inflatable bags mounted internally to the mast which, when supplied with pressurized air, lift movable sections of the nested mast resulting in erection of the mast, and, upon deflation by air control valves, the mast is retracted. The mast may also be operated by direct air pressure to a telescoping mast which is sealed airtight between sections. This embodiment would be most useful where the boat is in a fresh water environment where corrosion is less severe than a marine environment.  
         [0035]    Referring to FIG. 1, retractable mast sailboat system  10  features retractable mast  12  having lower section  14 , center section  16 , and upper section  18 . Mast boot  20  surrounds the lower portion of lower section  14  and shields fittings for lower section pneumatic line  22  and center section pneumatic line  24 . Pneumatic lines  22  and  24  travel through deck A of sailboat B. Lower section relief valve  26  and center section relief valve  28  are mounted on boot  20  for relieving pressure in mast lower section  14  and mast center section  16 , respectively.  
         [0036]    Referring to FIG. 2, lower mast section  14  and central mast section  16  are shown partially broken away, exposing lower lift bag  30  and upper lift bag  40 , respectively. Mast boot  20  houses portions of lower section pneumatic line  22  and center section pneumatic line  24  which each branch to respective lower section relief valve  26  and center section relief valve  28 .  
         [0037]    Referring to FIG. 3, there is shown a sectional view of lower mast section  14  having lower lift bag  30  internal to lower mast section  14  and lower mast boot  20  surrounding lower mast section  14 . Pneumatic lines and valves, and deck A are not shown.  
         [0038]    Referring to FIG. 4, there is depicted the retractable mast  12  in its fully retracted position wherein lower mast section  14  houses center mast section  16  and upper mast section  18 (not shown), and is surrounded at its lower end by boot  20  at deck A. Pneumatic lines and valves are not shown.  
         [0039]    Referring to FIG. 5 there is shown a sectional view of retractable mast  12  in a retracted position wherein lower mast section  14 , central mast section  16 , and upper mast section  18  are concentrically nested. Lower section pneumatic line  22  is connected to lower lift bag  30  shown in its deflated state. Center section pneumatic line  24  is connected to center section lift bag  40 .  
         [0040]    Center mast section  16  features upper stop  42  and lower stop  48  mounted internally near its upper end and lower end, respectively. Lower mast section  14  features upper stop  44  mounted internally near its upper end. Upper mast section  18  features lower stop  46  near its lower end. Upper mast section  18  features lower end wall  47 . Center mast section  16  features end wall  49 . Lower mast section  12  features lower end wall  51 . Mast  12  rests on base  50  attached by fasteners  52  to deck A of sailboat B. Pneumatic line  24  to lift bag  40  is shown truncated for illustration purposes, but in use would necessarily be of sufficient length for the full erection of center mast section  16 .  
         [0041]    In operation, retractable mast  12  is erected by supplying air under pressure through lines  22  and  24  to lower lift bag  30  and upper lift bag  40 , respectively, thus, forcing center mast section  16  and upper mast section  18  to telescope upward by pressing on their respective lower end walls  49  and  47 , respectively. Center mast section  16  is retained by its lower stop  48  when it reaches lower mast section stop  44 . Upper mast section  18  is retained by its lower stop  46  when it reaches center mast section upper stop  42 . When it is desired to retract mast  12 , air is released through valves  26  and  28  (see FIG. 2) from lower lift bag  30  and upper lift bag  40 , respectively, allowing upper mast section  18  and center mast section  16  to collapse by force of gravity into lower mass section  14 .  
         [0042]    Alternative embodiments may include  2 ,  3 , or more sections employing any desired number of inflatable bags. The upper mast sections may be open at their respective ends and inflatable bags contained in the upper mast section to assist in its erection. The mast sections may be circular, elliptical, or other configuration as desired and may be constructed of aluminum or other metal or synthetic material. The bags may be constructed of rubber or other flexible or expandable material or structure.  
         [0043]    Referring to FIG. 6, there is shown a sectional view similar to that of FIG. 5, illustrating another embodiment  60  of the retractable mast sailboat of the present invention. Retractable mast sailboat  60  has a retractable mast  62  consisting of mast lower section  64 , mast central section  66 , and mast upper section  68 . Lower chamber  69 , middle chamber  70 , and upper chamber  71  are formed by retractable mast lower section  64 , mast central section  66 , and mast upper section  68 . Central section upper stop  72  defines the furthest extension of mast upper section  68 . Lower section upper stop  74  defines the furthest extension of mast central section  66 .  
         [0044]    Upper mast section  68  features upper section airtight seal  76  which interacts with the inner surface of central mast section  66  to form an airtight seal for middle chamber  70 . Central mast section  66  features central section airtight seal  78  which interacts with the inner surface of lower mast section  64  to form an airtight seal for lower chamber  69 . Mast base  80  is directly attached to keel K by mast base fasteners  82  through boat hull H.  
         [0045]    Lower chamber pressure air inlet  84  allows the entrance of pressurized air into lower chamber  69 , middle chamber  70 , and upper chamber  71  through middle chamber lower wall  85  by means of middle chamber lower wall orifices  86 , and upper chamber lower wall  89  by means of upper chamber lower wall orifices  88 , respectively. Pressurized air is supplied by pressurized air bottle  123  through line  122 , the air pressure being controlled by pressure regulator valve  124 , and then passes through lower chamber pressure air inlet  84  and into lower chamber  69 .  
         [0046]    Referring to FIG. 7A, there is illustrated an embodiment of the inventive retractable mast sailboat  60  having rigging features and a supply of compressed air. Sailboat B features collapsible mast  62  in an extended state supported by inflated air bags or pressure sealed chambers as described above. The shrouds as shown are duplicated(not shown) on the opposite side of the mast. Air pressure is supplied to the retractable mast in the manner of the embodiment of FIG. 6, above. Upper backstay mount  130  is attached near the upper end of mast upper section  68 . Lower backstay mount  132  is attached to the stern portion of deck A, and backstay BS extends between and attaches to mast upper section  68  and lower backstay mount  132 .  
         [0047]    Upper front stay mount  134  is attached near the upper end of mast upper section  68 . Lower front stay mount  136  is attached to the bow portion of deck A, and front stay /FS extends between and attaches to mast upper section  68  and lower front stay mount  136 .  
         [0048]    Top shroud mount  138  is attached near the upper end of mast upper section  68 . Top shrouds TS are attached to and extend between mount  138  and boat deck A. Upper shrouds middle shroud mount  140  is attached near the upper end of mast central section  66 . Middle shrouds MS are attached to and extend between mount  140  and boat deck A. Lower shroud mount  142  is attached near the upper end of mast lower section  62 . Lower shrouds LS are attached to and extend between mount  142  and boat deck A.  
         [0049]    Stays FS and BS and shrouds LS, MS, and TS are made of flexible material such as wire rope so as to conveniently lay on the deck A when mast  62  is in a retracted position. One or more halyard pulleys HP are attached to the very top of mast  62  (halyards are not shown). Compressed air is supplied to extend mast  62  from air bottle  123  by means of air line  122  whose pressure is controlled by regulator valve  124 .  
         [0050]    Referring to FIG. 7B, there is presented a view in elevation similar to that of FIG. 7A, illustrating the installation of a sail, a boom, and a mast stiffener, with air pressure provided by an engine-driven compressor, wherein stiffener  150  is mounted between upper stiffener mount  152  attached at the upper end of mast  62 , and lower stiffener mount  154 , located on deck A. The stiffener  150  is preferably an integral rod or tube of a relatively unyielding metal such as stainless steel, so as to help support the mast  62  in its fully extended condition when under sail. Stiffener rod  150  also provides a convenient means of supporting sail S, by means of hoops  160 . A halyard pulley  162  is attached to the upper end of stiffener  150  to assist in raising the main sail S(the halyard is not shown).  
         [0051]    Boom bracket  164  is located at a convenient distance above deck A to opposing sides of mast lower section  64 . Boom bracket swivel  168  rotatably attaches boom  170  with boom bracket  164 . The lower edge of main sail S is attached to boom  174  by sail slot  172  formed along the upper length of boom  170 . Sail S may alternatively be fully supported by retractable mast  62  by means of hoops, zippers, slots, etc. as may be convenient. As shown in this embodiment, compressed air may be provided to mast  62  through pressure air lines  122  and regulator  124  by means of air compressor  180  driven by boat motor  182 .  
         [0052]    Referring to FIG. 7C, there is shown a plan view of the boom of FIG. 7B, illustrating the mast mounting bracket and stiffener rod, wherein retractable mast  62  supports boom bracket  164  by means of boom bracket mast mounts  166 . Boom bracket  164  surrounds stiffener  150 , shown in lower mount  154 , with enough clearance that stiffener  154  may be easily installed after the extension of retractable mast  62  to its maximum height. Boom bracket swivel  168  rotatably attaches boom  170  to bracket  164  by a pin in the manner of a hinge.(not shown) Sail slot  172  extends along the length of boom  170  to receive sail S(see FIG. 7B).  
         [0053]    In operation, retractable mast  62  is erected by supplying pressurized air from pressure air bottle  123  to mast lower chamber  69 . The pressurized air pushes on the middle chamber lower wall  85 , extending mast central section  66  upwardly. Simultaneously, pressurized air enters mast middle chamber  70  by means of middle chamber lower wall orifices  86  of such size as to allow maintenance of sufficient pressure within lower chamber  69  to raise mast central section  66 . Similarly, pressurized air entering middle chamber  70  exerts pressure on upper chamber lower wall  89 , extending mast upper section  68  upwardly. Upper chamber lower wall  89  may also have orifices therethrough to allow equalizing air pressure to build up within upper chamber  71 . In this mode of operation the mast upper section  68  is sealed at its top.  
         [0054]    One or both of the respective middle chamber lower wall  85  and upper chamber lower wall  89  may be omitted as desired, leaving the entire interior of retractable mast  62  open as a single pressurized chamber when extended for sailing. Once the mast is extended, the sail is inserted in sail slot  172  and hoops  160  placed over the stiffener  150 . The stiffener  150  is then erected by placing it through the clearance of boom bracket  164  and securing it between upper stiffener mount  152  and lower stiffener mount  154 . The sail S is then raised by pulling on the sail halyard(not shown) over sail halyard pulley  162 . A halyard(not shown) may be attached to the upper end of the retractable mast to assist in retracting the mast as desired. Air or other pressurized gas is preferred to hydraulic fluid, due to the additional weight of the fluid, increasing the weight of the erected mast, which tends to degrade overall sail boat performance.  
         [0055]    The features of the various embodiments may be combined as desire and any such combinations are considered to be within the scope of the present invention. A head sail(not shown) may be installed in each of the embodiments in a known manner. Inner seals may be located at upper mast section stops as well as lower mast section stops.  
         [0056]    It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims.