Buoys – rafts – and aquatic devices – Water skimming or walking device – Having stabilizing surface
Reexamination Certificate
2002-10-21
2004-07-20
Sotelo, Jesus D. (Department: 3617)
Buoys, rafts, and aquatic devices
Water skimming or walking device
Having stabilizing surface
C114S140000
Reexamination Certificate
active
06764364
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATIONS
Not applicable.
FEDERALLY SPONSORED RESEARCH
Not applicable.
SEQUENCE LISTING OR PROGRAM
Not applicable.
BACKGROUND—FIELD OF INVENTION
This invention relates to surf craft fin systems, specifically to such fin systems that use fins that snap in and out of plugs set into the surfboard.
BACKGROUND—DISCUSSION OF PRIOR ART
In the manufacture of surfboards, a body of plastic foam material is shaped and then covered with a layer of fiber-reinforced resin, normally fiberglass. One or more fins, most commonly three, are fixed to the bottom of the board at the rear, normally by one of three methods. One method, the so-called “glassed-in” method attaches the fins to the board by means of fiber-reinforced resin. A second method uses a so-called “fin-box”. A third method uses cylindrical plugs set into the board with resin. All three of these methods arc very popular. Each of these approaches has significant disadvantages.
Glassing the fins to the board (the “glassed-in” method) involves considerable labor costs and makes subsequent sanding and finishing of the board difficult. A further disadvantage of this fixing method is that the fiberglass fillet region at the base of the fin interferes with the hydrodynamics of the fins. This is believed to arise firstly from a reduction in the effective height of the fin, and from the outward flow of water caused by the fixing region, which in turn leads to turbulence and cavitation. There is an increased pressure drag cross sectional area. There is also a slightly increased skin drag length in the fillet of the fixing glass. As a result, the drive and bite afforded by the fins during turns is reduced and the performance and speed of the board is limited.
A further disadvantage of the attachment of fins by glassing on is that the fins must be present, fixed to the board, during all final finishing stages of the board's manufacture, increasing labor costs and restricting the quality of the final finish of the board.
In the use of the fin box method, a usually rectangular and sometimes cylindrical or oval cavity is formed in the board by the use of a router or hole saw and the fin box is inserted into this cavity. The most common fin box comprises a slot for the reception of the base of the fin, with a wider portion forming a lower slot at its base into which may be slid a pin, mounted horizontally through the front of the fin, to fix the front of the fin in the box. The rear of the fin is fixed by means of a vertical screw through a rearwardly extending portion of the base of the fin, this screw being driven into a drilled and tapped plate located in the rear end of the lower slot.
The use of fin boxes involves many disadvantages, including costly, labor-intensive fitting, an increase in the weight of the board, and looseness of the fin fixture, which causes reduced fin performance. Another disadvantage is that the joint between the box and the board cracks. Relative motion between the foam, the fiberglass skin, and the box material creates this crack. This cracking is worsened with increasing box size. This cracking results in leakage of water into the plastic foam material. The foam degrades when exposed to water if it is not repaired. These disadvantages of the fin box system, and others including the drag produced by the exposed slot at each end of the fin, are well known, and have lead to the general demise of this system.
The fin box does offer a theoretical advantage over the glassing-on of fins, and this is in the removability of the fins in the case of their need for replacement for repair, or during travel. The fin box design, however, makes removal and replacement difficult, and as a result this potential advantage is not realized.
Another variation of the fin box uses a horizontal pin in the rear of the box. This pin engages a horizontal cylindrical recess in the rear of the fin. The front of the fin is secured with a setscrew. The setscrew is threaded through a drilled hole in the plastic box. This setscrew is tightened against the front of the fin. There are further disadvantages of this method in addition to leakage and weight. The setscrew requires a special tool for insertion and removal of the fin. The setscrew is threaded into the plastic material of the fin box. These threads frequently strip requiring costly replacement of the entire box.
Another variation of the fin box includes a friction fit between the fin and the board with no other means of engagement. A further variation of this method includes a hook in the fin engaging the front of the fin into the front of the box. A replaceable snap in the rear of the box engages a protrusion on the back of the fin. With regards to the friction fit design there are several disadvantages. Besides the disadvantages of leakage and weight, another obvious disadvantage of the friction fit is that in the water this fit becomes lubricated. The lubricated friction fit fins can fall out. This is inconvenient and expensive. The snap-in method has a theoretical advantage in eliminating the requirement for a tool. This advantage is not realized because the replaceable snap, being in the box and not on the fin, requires costly repair and replacement of the box in the event of damage to any box feature used to retain the snap in the box. This snap-in method still suffers the disadvantages of added weight and leakage at the box edge.
Another variation of the fin box requires a hole routed completely through the surfboard. A screw is passed through the top of the board into the fin. Besides the other disadvantages of the fin box method mentioned above, this approach is difficult to manufacture. It weakens the surfboard in the thin tail area around the fins. This is especially severe near the center fin where the surfboard is usually thinnest. The through hole cuts away the entire “stringer” in this tail section. The stringer is a wooden “spine” running down the center of the entire length of the board. It adds strength and stiffness. This fin box design weakens the board in one of the most critical areas. This method also requires the engaging portion of the fin to be perpendicular to the surfboard lower surface. This prevents side fins from being set as custom camber angles. Most surfers prefer a certain favorite camber angle. This method sells fins with preset camber angles to try to overcome this disadvantage. This limits the options available to surfers using this fin system.
Another more recent variation of the fin box uses a rectangular plastic box set in a large cylinder of adhesive or resin. At least two tabs on the fins are inserted into slots in the cylindrical fin box. The tabs are secured by snaps in the plastic box. These snaps are a part of the box assembly and not in the fin. There are several disadvantages of this design. The large box adds weight to the board. A large cylindrical volume of the surfboard body is removed in order to set the box into the board. The large circular circumference leads to cracking and water leakage. This occurs where the fiberglass skin of the surfboard meets the edge of the box. The method of engaging the fins, being in the box, leads to inconvenient and costly repair of the box if damaged. This design was originally developed for very high-speed tow-in surfing on giant “macker” waves.
Another recent variation of the fin box uses a cam to laterally engage the fins. This is described in U.S. Pat. No. 5,975,974 to McCausland. During manufacture of the board a hole saw is used to cut three in-line overlapping cylindrical holes into the board. The box is shaped to fit this recess. It is shaped like three overlapping cylinders connected in-line at their sides. A cam mechanism in the box is rotated by hand. It applies a force to one side of a fin base protrusion or tabs. This method has a theoretical advantage. It eliminates a tool for fin insertion and removal. This advantage is not realized because the cam mechanism is in the box. If damaged it requires inconvenient, time consuming, and costly repair. This method
Hickman Scott Noble
Hinman Michael Roy
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