Buoys – rafts – and aquatic devices – Water skimming or walking device – Having stabilizing surface
Patent
1989-11-16
1991-07-09
Basinger, Sherman
Buoys, rafts, and aquatic devices
Water skimming or walking device
Having stabilizing surface
114127, 114140, B63B 3579
Patent
active
050301519
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to finned watercraft, such as surfboards and the like, of the kind having a stabilizing fin or fins, and especially to fins suitable therefor.
BACKGROUND ART
The sport of riding a board on the crest of a wave as it approaches the shore is old. European seafarers of the 18th century reported having seen this feat performed in the "Sandwich Islands".
In course of time, knowledge of this new, exciting sport spread from Hawaii to California, from whence it was introduced into such other countries as Australia, South Africa and so forth.
The traditional surfboards were heavy, curvilinear wooden artifacts, from 12 to 20 feet in length, and only the strongest surfers could readily handle them.
Subsequently, more modern surfboards began to be made from plastic, polyurethane foam, and fiberglass, with the fin set into what is termed a "fin-box" let into the underside or fixed insitu with fiberglass. While a fin-box admittedly provides a fin, set therein, with good resistance to laterally-applied force, the original object of the insert fin-box was apparently to allow for ease of transport, inasmuch as boards with the fins removed could be safely stacked one on top of the other. Damage of fins in transit was a major problem.
With a single fin, even moderately difficult conditions are enough to cause the "spin-out" which is so frustrating and even dangerous to the rider; this phenomenon to be caused by insufficient lateral adhesion between fin and water, and so attempts were made to counteract it by increasing the depth and lateral area of the base of the fin. The result was excessive drag and loss of maneuverability owing to the "keel effect" of the enlarged fin, which led to even poorer performance.
Variations of the finned board have been tried out (boardriders being notoriously prone to experiment) for example, laterally-spaced paired fins (the so-called "twin-fin board"). This produced a surfboard which was slightly more maneuverable and capable of "tighter" turns under ideal conditions but which tended to "spin-out" in big waves. It should here be noted that what in a conventional marine hull is called the chine is, in surfing parlance, termed the "rail". When a turn is made on a surfboard it is canted sideways and this action, with the keel effect of the fin keying in to the moving water, allows the turns to be made. A board having laterally paired fins will, when canted hard enough onto one of its rails, permit a quite tight turn, but is physically more difficult to cant over because the water funnels between the two fins and tends to keep the board wholly in the water, making turns difficult to accomplish.
Laterally-spaced, equally-sized triple fins have some advantages over and above paired fins inasmuch that such a board requires somewhat less "rail" to make a turn, but suffers from the fact that the two outer fins tend to over-react to such an extent that fine control may be compromised.
As a modification of the triple fin format, an arrangement involving a large centre-line fin flanked by two smaller, offset fins has been tried out but with limited success. Tandem fins have also been investigated and even five fin arrangements are not unknown. More significantly, recent experimentation has led to multi-fin arrangements in which the outer fins are angled with respect to the longitudinal centre-line of the board so that the leading edges of a laterally-spaced pair of fins are closer together than their trailing edges.
Coupled with the increasing proliferation of multi-fin boards is the trend for boards to be made shorter --as short as 5 feet--and also to be lighter. Such a combination results in tail-heavy boards, unbalanced by the sheer weight to their fin-boxes, if the box system is utilized.
DISCLOSURE OF INVENTION
It has now been found feasible to dispense completely with both fin-boxes and labor-intensive fixed fins, by the provision of a fin affixing system which permits single or multiple fins to be rapidly and inexpensively mounted upon the underside of
REFERENCES:
patent: 2931332 (1960-04-01), Hebrank
patent: 2972974 (1961-02-01), Follett
patent: 3087452 (1963-04-01), Grimston
patent: 3089157 (1963-05-01), May
patent: 3516099 (1970-06-01), Morey et al.
patent: 3747138 (1973-07-01), Morgan
patent: 3965514 (1976-06-01), Shafer
patent: 4320546 (1982-03-01), Knox
Basinger Sherman
Brahan Thomas J.
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