Fin attachment system allowing roll angle alignment

Buoys – rafts – and aquatic devices – Water skimming or walking device – Having stabilizing surface

Reexamination Certificate

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Details

C114S130000

Reexamination Certificate

active

06244921

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a fin attachment structure for surfboards or other water craft such as sailboards and boats, and, more specifically, to an improved fin attachment structure that allows the roll angle alignment of the fin to be adjusted.
2. Background Art
Conventional surfboards and other water vehicles are often provided with fixed fins or skegs on their underside. These fins are subjected to great strains and stresses due to the nature of water sports and are often damaged. For example, in the case of a surfboard, the fin(s) are susceptible to being pushed into hard sand or rocks on the shore. Because the fins are fixed on conventional surfboards, it is often necessary to dispose of the surfboard once the fin or fins are damaged. Furthermore, the fixed fin configuration makes storage, handling and shipping of the surfboard very cumbersome. The fins are also often damaged in storage and shipping.
Another disadvantage of surfboards and other water craft employing rigidly fixed fins is that it is difficult to align the roll angle of the fin or fins, (i.e. the angular position of the fin relative to a longitudinal axis on the bottom surface) during the manufacturing process. Even if the roll angle is as desired when the fin is first mounted, this angle may shift as the manufacturing process progresses. Aligning the roll angles of the fins properly is particularly difficult when there is more than one fin. For example, the roll angle of multiple fins (such as in a side-by-side configuration) typically must be aligned with respect to each other to give the surfboard the desired surfing characteristics. Since the fins are fixed, any misalignment in roll angle cannot be corrected and the board may be ruined.
As mentioned above, it is believed that the fin roll angle can be important in determining certain surfing characteristics of the board. Being able to adjust a fin's roll angle could allow a surfer to customize the performance of the board. However, the fixed configuration of conventional fins prevents the surfer from adjusting the fins to a desired angular position to correct or vary the surfboard's characteristics.
Another disadvantage of a surfboard fin that is not removable or adjustable is that other geometrically shaped fins cannot be substituted for the normal fin to provide the board with different characteristics. Restriction to a single fin limits the performance characteristics of the board. Likewise restriction to a particular fin roll angle also limits the performance.
It is noted that similar problems also affect other water craft, such as sail boards, small boats and the like.
To prevent the common problems and disadvantages of the current fin attachment systems, an improved fin attachment system is required. This improved fin attachment system should allow the fin to be removed and reattached and allow the roll angle of the fin relative to the surfboard to be adjusted. Such an improved system would provide major advancements in functionality and practicality over the present technology. It would allow various fin shapes to be used and would allow the fin roll angle to be adjusted. It would also allow broken fins to be easily replaced, and finally, various water craft would be more easily manufactured, stored and shipped.
SUMMARY
The present invention overcomes the common problems and disadvantages of prior fin attachment assemblies with a fin attachment structure wherein the roll angle of the fin can be readily adjusted. Further, the fin attachment arrangement embodying the present invention provides a structure wherein a fin may be easily inserted or removed in a minimum amount of time.
The fin assembly has a fin mounting base installed within the underside of a water craft. The mounting base has an elongated channel defined by a pair of longitudinally extending side walls which terminate in a pivot block at each end of the channel. Each of the pivot blocks has a semi-circular shaped groove for receiving a cylindrical rotating bar, and threaded hole for receiving a threaded screw. The rotating bar has reduced diameter ends which fit into the semi-circular shaped grooves in the two pivot blocks. The radius of each groove is approximately the same as the radius of the reduced diameter ends of the bar. The rotating bar also has an elongated slot and a pin which perpendicularly traverses the slot. The rotating bar fits inside the elongated channel in the mounting base and is held in place by two cap pieces which are screwed onto each end of base such that they overlap the reduced diameter ends of the rotating bar. Each cap piece has a semi-circular shaped groove similar in size to the groove associated with the aforementioned pivot blocks, although it is not quite as deep. The upper portion of the reduced ends of the rotating bar are disposed within the grooves of the end pieces. Each of the end pieces has a through hole that overlies the threaded hole of the adjacent pivot block in the mounting base. In addition, there is a countersink depression in the top surface of each end piece at the top of the through hole. This depression accommodates the head of a retaining screw which extends through the through-hole and is threaded into the threaded hole of the pivot block. When fully tightened down, the retaining screws and end pieces trap and hold the reduced ends of the rotating bar so as to prevent the bar from rotating in relation to the mounting base. However, when the retaining screws are loosened slightly (although not removed so as to retain the cap pieces on the mounting base) the rotating bar is freed and can rotate in relation to the base within the pivot blocks.
The rotating bar is inserted such that its elongated slot faces upward. The fin has an extension protruding from its bottom that has a cross-sectional shape which matches the shape of the slot in the rotating bar. There is also a rotated L-shaped cut out in the fin extension having the shape of a clockwise rotated “L”. The short leg of the cutout opens at the bottom surface of the fin and the long leg is directed towards the front of the fin. The cut-out forms a cantilevered finger that is hooked under the pin in the rotating bar. In order to seat the fin and thereby fix its longitudinal position, the fin is pulled backwards such that the pin of the rotating bar rides over the upper surface of the finger deflecting it downward slightly until the pin seats into a concave section at the proximal end of the finger. The finger then springs back into its original position, thereby trapping the pin and holding the fin in place. The fin (or what is left of it if broken) can be removed and replaced, by simply forcing the fin forward such that the cantilevered finger disengages from the pin in the rotating bar.
In operation, the fin's roll angle can be adjusted by loosening the rotating screws and freeing the rotating bar so that it can be rotated. After the fin is rotated to its desired roll angle the screws can be tightened and the fin will be held in this new roll angle. Note that it is not necessary when removing and replacing the fin to loosen the end cap screws, and so the roll angle will not be changed once the new fin is installed.
In addition to the just described benefits, other objectives and advantages of the present invention will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.


REFERENCES:
patent: 1703868 (1929-03-01), Chisholm, Jr.
patent: 4811674 (1989-03-01), Stewart

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