US3649979A - Swim fin - Google Patents

Swim fin Download PDF

Info

Publication number
US3649979A
US3649979A US46061A US3649979DA US3649979A US 3649979 A US3649979 A US 3649979A US 46061 A US46061 A US 46061A US 3649979D A US3649979D A US 3649979DA US 3649979 A US3649979 A US 3649979A
Authority
US
United States
Prior art keywords
water
blade
wall
jet
foot pocket
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US46061A
Other languages
English (en)
Inventor
Douglas K Macniel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Aqua Lung America Inc
Original Assignee
US Divers Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by US Divers Co Inc filed Critical US Divers Co Inc
Application granted granted Critical
Publication of US3649979A publication Critical patent/US3649979A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B31/00—Swimming aids
    • A63B31/08—Swim fins, flippers or other swimming aids held by, or attachable to, the hands, arms, feet or legs
    • A63B31/10—Swim fins, flippers or other swimming aids held by, or attachable to, the hands, arms, feet or legs held by, or attachable to, the hands or feet
    • A63B31/11—Swim fins, flippers or other swimming aids held by, or attachable to, the hands, arms, feet or legs held by, or attachable to, the hands or feet attachable only to the feet

Definitions

  • Water-intake (scoop) or mouth openings are provided in the top of the tin and adjacent the foot pocket or other mounting means.
  • Water-outlet or jet-exhaust openings are provided at the tip of the blade and are directed away from the foot pocket.
  • Wall means are provided to define nozzle passages connecting the water-intake openings with the jet-exhaust openings to thereby cause high-velocity jets of water to emanate from the blade tip, particularly during each downstroke of the foot of a swimmer who is in a face-down position.
  • the swim fin comprises a blade adapted to be employed in propelling the swimmer through the water, means to secure the blade to the foot of a swimmer, and passage and orifice means responsive to the downward movement of the foot of a downwardly facing swimmer to cause jets of water to emanate from the tip of the blade and in directions away from the foot.
  • relatively large-area water-scoop or mouth openings are formed in the top of the blade adjacent the inner end of the foot pocket, and relatively small-area water-outlet or jet-exhaust openings are formed in the tip of the blade.
  • Nozzle passage means are formed through the blade from such mouth openings to such jet-exhaust openings, and are of decreasing cross-sectional area in directions toward the jet-exhaust openings in order to effect high-velocity jet exhaust therethrough.
  • FIG. I is a view, partially in side elevation and partially in longitudinal section, showing the swim fin as mounted on the downwardly moving foot of a swimmer who is swimming in a face-down position;
  • FIG. 2 is a top plan view of the fin
  • FIG. 3 is a longitudinal central section taken along line 3-3 of FIG. 2;
  • FIGS. 4 and 5 are, respectively, transverse sectional views taken along lines 4-4 and 5-5 ofFIG. 2.
  • top of the blade denote that portion of the fin blade which is uppermost when the wearer is standing on the ground. Conversely, the bottom of the blade is that portion which is lowermost when the wearer is in standing position. Only one swim fin is described herein, it being understood that the swim fin for the other foot is identical or is substantially identical to the one illustrated and described. All of the figures, excepting FIG. 1, show the swim fin in its natural (unstressed and undeflected) condition.
  • the'swim fin is illustrated to comprise a blade adapted to be secured by mounting means I] to one foot 12 (FIG. I) of the swimmer.
  • the mounting means 11 is so constructed that the blade 10 is generally in a plane perpendicular to the leg of the wearer when the wearer is in standing position on the ground or other supporting surface. The blade then extends away from the ankle of the wearer, in line with (and outwardly of) the instep and toes thereof.
  • the mounting means I1 comprises wall means 13 to define a foot pocket or chamber 14 adapted to receive the toes and the instep of the foot 12. It is to be understood that additional wall means, not shown, may be provided to enclose the ankle and/or heel.
  • a heel strap 15 extends around the heel of the wearer and is connected at its ends, through adjustable connections, to lugs or ears 16 formed integrally on the sides of wall means 13.
  • Side ribs 17 are provided along the side edge portions of the blade 10 and of wall means 13.
  • the end regions of the side ribs 17 may be generally parallel to each other, as shown in FIG. 2, but the central regions thereof diverge substantially and in a direction away from the ankle of the wearer. Thus, the blade 10 is caused to be substantially wider than is the mounting meansll.
  • intermediate ribs 18 Mounted in equally spaced relationship intermediate the forward portions of side ribs 17 are intermediate ribs 18. Such ribs are parallel to each other and extend forwardly from the wall means 13 which defines the foot pocket 14. Stated more definitely, the intermediate ribs 18 extend forwardly from the toereceiving portions of wall means 13. In the illustrated embodiment, there are two such intermediate ribs 18, and the spacing between such ribs is approximately equal to the spacing between either of such ribs and the adjacent side rib 17.
  • the blade 10 comprises, in addition to the various ribs, a bottom wall 20 which covers the entire bottom and forward portion of the swim fin.
  • a bottom wall 20 which covers the entire bottom and forward portion of the swim fin.
  • Such wall 20 merges at a thickened portion 21 (FIG. 3) with the bottom portion of the wall means 13.
  • the bottom wall 20 thus extends to the wall means for defining the foot pocket.
  • a top wall 22 is provided in spaced relationship from bottom wall 20, and covers the entire region of the fin blade 10 forwardly of the top-wall edges 23 illustrated in FIGS. 2 and 3. Such edges 23 are spaced a substantial distance forwardly from the wall means 13.
  • each of the top and bottom walls 22 and 20 is integral with all of the ribs 17 and 18, such ribs serving to maintain the walls 20 and 22 spaced from each other as illustrated.
  • the ribs 17 and 18 not only extend between the walls but also extend above and below the walls in order to increase the strength of the ribs and also to provide deflector or baffle means for guiding the water as it flows along the exterior surfaces of walls 20 and 22.
  • the ribs 17 and 18 are relatively large and thick at regions adjacent the wall means 13. From such thick portions, the ribs taper progressively in a forward direction and become smaller as illustrated in FIG. 5. Thus, the walls 20 and 22 come progressively closer to each other and, additionally, the blade portions remote from the foot pocket are more flexible than are the blade portions adjacent thereto.
  • Walls 20 and 22, and theribs l7 and 18, cooperate with each other to define three nozzle passages 24, 25 and 26 (FIGS. 3-5).
  • Passage 24 is generally rectangular in section and is defined between a side rib 17 and the adjacent intermediate rib 18, and also between the portions of top and bottom walls 22 and 20 extending between such ribs.
  • passage 26 is defined between the remaining side rib l7 and the adjacent intermediate rib 18, as well as between the wall portions 22 and '20 extending between such ribs.
  • the central passage 25 is formed between the two intermediate ribs 18 and between the top and bottom wall portions 22 and 20 extending between such ribs.
  • each of the passages 24-26 is illustrated as being relatively wide but thin (that is to say, there is only a short distance between the opposed portions of walls 20 and 22).
  • passages 24-26 remote from wall means 13 constitute water-outlet or jet-exhaust openings or orifices 27 (FIG. 3) which are directed forwardly and directly away from the wall means 13. Stated otherwise, such jet-exhaust openings or orifices 27 direct water generally in the plane of the tip region of the blade 10, and away from the foot and ankle of the wearer.
  • the water-intake or mouth openings 28 face generally upwardly, when the wearer is in standing position on a supporting surface, that is to say such openings face up and approximately 90 away from the direction of facing of jet-exhaust openings 27 when the wearer is standing on such surface.
  • the downstroke of the leg and foot causes water to enter the mouth openings 28 and then pass around a gentle curve (formed by wall portions 29 and 30 shown in FIG. 3) to the tip regions of the blade for exhaust through jet-exhaust openings 27.
  • the water not only passes around the gentle curve but also rapidly accelerates due to the progressively decreasing cross-sectional areas of the passages 24-26, the result being the efficient creation of three highvelocity jet exhausts from the tip of the blade and away from the ankle of the wearer.
  • the entire swim fin, excepting the heel strap and associated fastener means, is molded integrally from an elastomeric material such as natural or synthetic rubber.
  • the elastomeric material should be sufficiently hard to prevent excessive deformation.
  • the shore hardness may be about 70.
  • the present swim fin is characterized by the advantage that, despite the presence of passages 24-26, molding may be readily effected.
  • FIG. 1 shows the fin mounted on the foot l2ofa wearer who is swimming in a facedown position.
  • FIG. 1 illustrates the condition which occurs when the wearer is moving forwardly through the water and is simultaneously kicking downwardly the foot and leg portion illustrated in the drawing, the direction of kicking being indicated by the arrow C. ,y j
  • the illustrated downstroke creates thrust, and also generates relatively high pressure regions H.P.l and H.P.2
  • the downstroke also causes a certain amount of upward flexing of the blade, espedaily at portions thereof relatively adjacent the tip (namely, portions remote from wall means vl3).
  • the first effect is direct thrust of the blade wall 22 against the water.
  • Such thrust when the fin is in the position shown in FIG. 1, has vertical and horizontal components, and only the latter is operative to produce forward propulsion of the swimmer through the water.
  • the horizontal component of direct thrust is greatest adjacent the highpressure region H.P.l, since the portion of wall 22 adjacent such region is inclined sharply upwardly.
  • there is very little horizontal component of direct thrust adjacent highpressure region H.P.2 since the fin is, when in the FIG. 1 position, only very slightly inclined adjacent such region.
  • the second effect is different from the direct-thrust effect described above, and instead is jet thrust.
  • the jet thrust effect results from converting the relatively no-work" region adjacent area H.P.2 into a useful jet pump.
  • Such pumpf' causes flow of water through passages 24-26, as shown by arrows 33, with consequent jet thrust action at the blade tip.
  • such pump augments the flow along the blade surfaces and as indicated by arrows 31 and 32.
  • the water scoop (mouth or intake) openings 28 at the forward ends of nozzle passages 24-26 face in the general direction of blade movement in response to the downward blade-kicking indicated by arrow C. This is because the waterscoop openings 28 are directed transversely to the plane of blade 10 (FIG. 3). Therefore, the high pressure at region H.P.2 is very effective in causing flow (arrows 33) into and through nozzle passages 24-26.
  • the water entering such passages passes around a gentle corner (surfaces 29 and 30) and then accelerates efficiently (along paths generally in the plane of blade 10) until it discharges at high speed through jet-exhaust openings 27.
  • Such acceleration results from the progressively decreasing cross-sectional areas of the passages 24-26 as the exhaust openings or orifices 27 are approached.
  • the direction of jet exhaust is away from the foot and ankle of the wearer, namely, away from mounting means 1 1.
  • the tip-located jets from passages 24-26 serve to'minimize the turbulence and vortexing which is inherently present at the blade tip due to the kicking action. The result is greater efficiency of propulsion.
  • the jets are through the tip-located orifices 27, instead of through the bottom wall 20, there is a relatively greater thrust in the horizontal (useful) direction.
  • the uppermost arrow 33 is much closer to the horizontal than would be any corresponding arrow representing flow through bottom wall 20.
  • the jet exhaust representedby the uppermost arrow 33 in FIG. 1 is not to a high pressure region, as would be the case if discharge were through top wall 22 adjacent region H.Pl.
  • the tip-located orifices 27 may not be inclined away from the plane of the tip region of blade 10. They may, for example, be inclined in a direction somewhat counterclockwise from that shown in FIG. 1, with consequent reduction of the angle between uppermost arrow 33 and the horizontal.
  • jets from orifices 27 are directed into the main body of water and not against or adjacent any portion of the fin itself.
  • any jets were substantially forward of the tip region of the fin, which diminished the propulsive action created by the jets.
  • a swim fin which comprises:
  • first and second side ribs extending forwardly from said foot pocket wall means
  • said top wall terminating, at the inner end portion thereof relatively adjacent said foot pocket wall means, at an inner edge which is spaced from said foot pocket wall means, said top wall terminating, at the outer end portion thereof remote from said foot pocket wall means, in a region which is adjacent the tip of said blade, at least part of said blade wall means being a bottom wall which is spaced from said top wall, said bottom wall terminating, at the outer end portion thereof remote from said foot pocket wall means, in a region which is adjacent the tip of said blade, said top and bottom walls cooperating with each other in defining at least one water passage, said water passage terminating at its inner end in a water-scoop opening which is defined in part by said inner edge of said top wall, said water passage terminating at its outer end in a jetexhaust orifice which is defined between said outer end portions of said top and bottom walls, said orifice being directed away from said foot pocket walls means.
  • a swim fin which comprises:
  • a blade adapted to be employed in propelling a swimmer through the water
  • water-scoop means provided on the top of said blade and directed to receive water in response to downward movement of the foot of said swimmer when said swimmer is in a face-down position
  • said water-scoop means being disposed relatively adjacent said mounting means
  • jet-exhaust means provided at the other end of said blade remote from said mounting means, said jet-exhaust means being directed to discharge water in a direction away from said mounting means, said jet-exhaust means comprising orifice means disposed at the extreme tip of said other end of said blade, said tip being the portion of said blade most remote from said mounting means, and passage means to conduct water from said water-scoop means to said jet-exhaust means for discharge through the latter, said passage means comprising at least one nozzle passage through said blade, the walls of said nozzle passage being shaped to effect acceleration of water passing from said water-scoop means to said jet-exhaust means, said shaping being such that said nozzle passage has a cross-sectional area which decreases progressively in a direction toward said jet-exhaust means, and throughout substantially the entire distance from said water-scoop means to said jet-exhaust means.
  • a swim fin which comprises:
  • a blade adapted to be employed in propelling a swimmer through the water
  • water-scoop means provided on the top of said blade and directed to receive water in response to downward movement of the foot of said swimmer when said swimmer is in a face-down position
  • said water-scoop means being disposed relatively adjacent said mounting means
  • jet-exhaust means provided at the other end of said blade remote from said mounting means
  • jet-exhaust means being directed to discharge water in a direction away from said mounting means
  • said passage means being defined in part by upper and lower walls which extend from said water-scoop means to said other end of said blade and substantially separate the water flowing through said passage means from the water passing along the exterior of said blade.
  • jet-exhaust means comprises orifice means disposed at the extreme tip of said other end of said blade, said tip being the portion of said blade most remote from said mounting means.
  • said passage means comprises at least one nozzle passage through said blade, the walls of said nozzle passage being shaped to effect acceleration of water passing from said water-scoop means to said jet-exhaust means.
  • a swim fin which comprises:
  • first and second side ribs extending forwardly from said foot pocket wall means
  • intermediate rib means located between said first and second side ribs and extending forwardly from said foot pocket wall means
  • top wall terminating, at the inner portion thereof relatively adjacent said foot pocket wall means, in inner edges which are spaced forwardly from said foot pocket wall means, and
  • a bottom wall connected to said side ribs and to said intermediate rib means, said bottom wall extending to the tip of said blade, said bottom wall forming the bottom surface of the blade of said fin, said bottom wall being spaced from said top wall, at least portions of said bottom wall extending to said foot pocket wall means, said top and bottom walls cooperating with said side ribs and with said intermediate rib means in defining a plurality of water passages, each of said water passages terminating at its inner end in a water-scoop opening which is defined in part by one of said inner edges of said top wall,
  • each of said water passages terminating at its outer end in a jet-exhaust orifice which is defined at the tip of said blade between the extreme outer edges of said top and bottom walls, said orifice being directed away from said foot pocket wall means.
  • foot pocket wall means, said side ribs, said rib means, and said top and bottom walls are formed integrally of a single mass of elastomeric material.
  • first and second ribs and said intermediate rib means include portions which extend, respectively, above and below said top and bottom walls, such extension portions serving to direct water along the exterior surfaces of said top and bottom walls.
  • said intermediate rib means comprises two parallel ribs spaced from each other.

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Physical Education & Sports Medicine (AREA)
  • Toys (AREA)
  • Professional, Industrial, Or Sporting Protective Garments (AREA)
US46061A 1970-06-15 1970-06-15 Swim fin Expired - Lifetime US3649979A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US4606170A 1970-06-15 1970-06-15

Publications (1)

Publication Number Publication Date
US3649979A true US3649979A (en) 1972-03-21

Family

ID=21941375

Family Applications (1)

Application Number Title Priority Date Filing Date
US46061A Expired - Lifetime US3649979A (en) 1970-06-15 1970-06-15 Swim fin

Country Status (5)

Country Link
US (1) US3649979A (https=)
JP (1) JPS4836519B1 (https=)
DE (1) DE2128725A1 (https=)
FR (1) FR2095243B1 (https=)
GB (1) GB1261168A (https=)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4083071A (en) * 1976-01-20 1978-04-11 Roland Forjot Swim flippers
US4627820A (en) * 1985-06-18 1986-12-09 Penebre Larry M Swim fin
US4887985A (en) * 1984-05-03 1989-12-19 Amf Incorporated Swim fin provided with a self-shaping, fluid flow conveying and controlling canal-like member
US5387145A (en) * 1993-07-07 1995-02-07 Wagner; John L. Swim fins
US5702277A (en) * 1993-07-07 1997-12-30 Wagner; John Lee High performance swim fin
EP0908198A1 (en) * 1997-09-12 1999-04-14 HTM SPORT S.p.A. Swimming flipper
US20040029465A1 (en) * 2002-08-06 2004-02-12 Landel Technology, Inc. Swim training fin
WO2004064943A1 (en) * 2003-01-23 2004-08-05 Lessing, Stefanus, Christian Flippers
US20040209534A1 (en) * 2003-04-17 2004-10-21 Graham Richard W. Swim fin with fabric foot pocket
US20050026519A1 (en) * 2003-08-01 2005-02-03 Chia-Te Hu Diving fins
WO2007085639A1 (de) 2006-01-26 2007-08-02 Norbert Sack Flosse, insbesondere tauchflosse
US20090325434A1 (en) * 2008-06-30 2009-12-31 Warnaco Swimwear, Inc. Swim fin
US20130023168A1 (en) * 2011-07-18 2013-01-24 Qbas Co., Ltd. Fin
US9004966B2 (en) 2011-10-05 2015-04-14 Brian Mayer Swim fin attachment
US9364717B2 (en) 2014-01-16 2016-06-14 Kathleen Davis Swimming fin
WO2017190189A1 (en) * 2016-05-06 2017-11-09 DMC Industries Pty Ltd Swimming flipper

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4910221U (https=) * 1972-05-02 1974-01-28
JPS53115539U (https=) * 1977-02-23 1978-09-13
US4940437A (en) * 1988-06-03 1990-07-10 Piatt John A Swim fin with harness

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3032787A (en) * 1960-03-25 1962-05-08 Mazzella Nicolas Swimming-flipper with staged propulsion-surfaces
US3055025A (en) * 1959-04-20 1962-09-25 Ferraro Luigi Swimming fins or flippers
US3183529A (en) * 1964-03-16 1965-05-18 Beuchat Georges Swimmer's foot-fin with thrust-accelerating device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3055025A (en) * 1959-04-20 1962-09-25 Ferraro Luigi Swimming fins or flippers
US3032787A (en) * 1960-03-25 1962-05-08 Mazzella Nicolas Swimming-flipper with staged propulsion-surfaces
US3183529A (en) * 1964-03-16 1965-05-18 Beuchat Georges Swimmer's foot-fin with thrust-accelerating device

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4083071A (en) * 1976-01-20 1978-04-11 Roland Forjot Swim flippers
US4887985A (en) * 1984-05-03 1989-12-19 Amf Incorporated Swim fin provided with a self-shaping, fluid flow conveying and controlling canal-like member
US4627820A (en) * 1985-06-18 1986-12-09 Penebre Larry M Swim fin
US5387145A (en) * 1993-07-07 1995-02-07 Wagner; John L. Swim fins
US5702277A (en) * 1993-07-07 1997-12-30 Wagner; John Lee High performance swim fin
EP0908198A1 (en) * 1997-09-12 1999-04-14 HTM SPORT S.p.A. Swimming flipper
US6053788A (en) * 1997-09-12 2000-04-25 Htm Sport S.P.A. Swimming flipper
US20040029465A1 (en) * 2002-08-06 2004-02-12 Landel Technology, Inc. Swim training fin
US6979241B2 (en) * 2002-08-06 2005-12-27 Zoomers Swim training fin
WO2004064943A1 (en) * 2003-01-23 2004-08-05 Lessing, Stefanus, Christian Flippers
US20040209534A1 (en) * 2003-04-17 2004-10-21 Graham Richard W. Swim fin with fabric foot pocket
US20050026519A1 (en) * 2003-08-01 2005-02-03 Chia-Te Hu Diving fins
WO2007085639A1 (de) 2006-01-26 2007-08-02 Norbert Sack Flosse, insbesondere tauchflosse
DE102006032381A1 (de) * 2006-01-26 2007-08-09 Norbert Sack Tauchflosse mit Rückstoßprinzip
DE102006032381B4 (de) * 2006-01-26 2014-06-26 Norbert Sack Tauchflosse mit Rückstoßprinzip
US20090325434A1 (en) * 2008-06-30 2009-12-31 Warnaco Swimwear, Inc. Swim fin
US7753749B2 (en) 2008-06-30 2010-07-13 Warnaco Swimwear, Inc. Swim fin
US20130023168A1 (en) * 2011-07-18 2013-01-24 Qbas Co., Ltd. Fin
US9004966B2 (en) 2011-10-05 2015-04-14 Brian Mayer Swim fin attachment
US9364717B2 (en) 2014-01-16 2016-06-14 Kathleen Davis Swimming fin
WO2017190189A1 (en) * 2016-05-06 2017-11-09 DMC Industries Pty Ltd Swimming flipper
CN109069905A (zh) * 2016-05-06 2018-12-21 Dmc工业股份有限公司 游泳脚蹼
US20190151718A1 (en) * 2016-05-06 2019-05-23 DMC Industries Pty Ltd Swimming flipper
US10688347B2 (en) 2016-05-06 2020-06-23 DMC Industries Pty Ltd Swimming flipper
CN109069905B (zh) * 2016-05-06 2020-08-21 Dmc工业股份有限公司 游泳脚蹼

Also Published As

Publication number Publication date
JPS4836519B1 (https=) 1973-11-05
GB1261168A (en) 1972-01-26
DE2128725A1 (de) 1971-12-16
FR2095243B1 (https=) 1973-01-12
FR2095243A1 (https=) 1972-02-11

Similar Documents

Publication Publication Date Title
US3649979A (en) Swim fin
US5387145A (en) Swim fins
US3183529A (en) Swimmer's foot-fin with thrust-accelerating device
US4541810A (en) Swimming apparatus
US3422470A (en) Swimming fin
US3411165A (en) Swim fin
US3810269A (en) Swimmer{40 s foot fin
US5702277A (en) High performance swim fin
US3107371A (en) Swimming device
US4083071A (en) Swim flippers
US4934971A (en) Swim fin
US3913158A (en) Swimming fins
US4627820A (en) Swim fin
US6764362B1 (en) Monofin swimming apparatus
US5348503A (en) Underwater paddle and vertical fin for swimmer
US5338235A (en) Swimming aid
US4737127A (en) Hydrodynamic swim fin
US4838824A (en) Swimming flipper
US5643027A (en) Freestyle stroke swim training paddle
US6183327B1 (en) Swim fin structure
US4316300A (en) Swim paddles
KR102171413B1 (ko) 수영용 오리발
US3428980A (en) Swimming equipment
US6537114B2 (en) Adjustable swim fin
US4895537A (en) Swim fin