DE8914642U1 - fin - Google Patents

Description

Holmer Dangschat 6.12.89

The invention relates to a fin for a surfboard according to the preamble of claim 1.

Small surfboards, e.g. slalom boards, are mainly used without a daggerboard, only with a fin. A small fin is advantageous for fast beam reach, while a large fin is needed for cow sailing to reduce drift. An adjustable fin would be an advantage here.

For example, the O-3 DE 344.O533 *' has a Vario fin system whose surface can be changed during travel. The fin is pivoted vertically inwards about a pivot point located relatively far in front of the stern. This has the disadvantage that the fin has an unfavourable shape for the airflow when extended and that a surfboard with a special fin box is required.

In the magazine Surf 9/89 p.38, sword-like fins are presented that are pushed through from above. Although they have the desired effect in terms of aerodynamics, the fin that protrudes upwards is a disadvantage. In addition, a surfboard with a special fin box is also required.

The invention is based on the object of specifying a fin that can be adjusted while riding, has a streamlined shape, does not protrude upwards and fits on a surfboard with a conventional fin box.

This object is achieved by the characterizing features of claim 1.

The advantages of the invention are that the fin can be changed with the foot while riding and that it can be used on surfboards with a normal fin box.

Advantageous embodiments of the invention can be found in the dependent claims.

The invention is explained below using exemplary ^embodiments with the aid of the drawings.

Show it

Fig.l a longitudinal section through the tail of a surfboard ib with attached fin according to the invention and the

% water pump used to operate,

Fig.2 a section through the base plate of the water pump

with a possible arrangement of the valves,

ti Fig. 3 the base plate with the valves seen from above and Fig.A another embodiment with a fixed middle part and a movable outer part.

In Fig. 1, a fin according to the invention is shown with a fixed outer part 1 and a movable inner part 2 with a seal 3 and a rope U for limiting the travel. The connection 6 of a connecting line 7 with a foot pump 8 can be seen on the mounting foot 5 of the fin. Parallel to the line 7, a line 7a is provided which reaches into the water. It can be seen in Figs. 2 and 3.

To increase the fin area, press your foot on the

, pump 8 is activated. Water in the pump flows through valve 10, line 7, connection 6 and hole 12 into the interior 13 of the fixed fin part 1 and presses fin part 2 downwards. When pump 8 is released, it is pushed apart again by a built-in spring 14. Valve 10 closes and valve 11 opens. Water is sucked into the pump through line 7a that reaches into the water. This process is repeated until rope 4 is taut. This requires approximately 10 pump strokes.

To reduce the fin surface, the pump is turned anti-clockwise with the foot until the valve 11 is connected to the line 7 and the valve 10 is connected to the opening 9. The rotation of the pump 8 is indicated in the fins 1 by not shown

Aryan lacje orler rests limited.

If the pump 8 is now stepped on, the valve 10 opens and the water in the pump B sprays out through the opening 9. When released, the valve 10 closes due to the negative pressure created and water flows through the opening valve 11 from the intake chamber 13 into the channel via the line 7 into the pump 8. The negative pressure created inside the fin pushes the movable fin part 2 upwards a little. Stepping down causes the valve 11 to close and the valve 11 to open, so that the water previously sucked out of the fin is released into the open . This process can be repeated until the movable part 2 of the fin is completely retracted.

Another design example with a fixed inner part 16 and a movable outer part 16 is shown in Fig. 1. The interior of the fin is connected to a pressure vessel 20 filled with liquid gas via a bore 17, a line 18 and a valve 19. When the valve is set, gas flows into the fin and pushes the movable part of the fin downwards. To avoid excessive pressure forces, a pressure changer (not shown) or a shut-off valve could be used.

In the other position of the valve 19, the pressure vessel 20 is closed and the line 18 is vented. The gas flows out into the open. In this embodiment, the moving part 16 of the fin is retracted using a rubber cable 21 housed inside the fin, which is redirected over a roller 22 to accommodate the required length. This embodiment could be particularly interesting for regatta sailors, since only the valve 19 needs to be switched to operate it.

If surfboards with a fin box that is open at the top are used, the application of the invention is even simpler, since the pressure line can be connected on the top of the surfboard.

Claims (2)

Expectations I.Fin for a surfboard, the surface of which can be changed during travel, characterized in that the fin consists of an outer part (1) and at least one inner part (2), that one of these parts is attached to the surfboard and that at least one of the other parts is designed to be telescopically displaceable in the longitudinal direction of the fin and that this displacement takes place through the pressure effect of a fluid. 2.Fin according to claim 1, d characterized in that water is used as the fluid. 3.Fin according to claim 2, d characterized in that the water is Pump (8) is conveyed into the interior (13) of the fin. A.Fin according to claim 3, characterized in that the pump (8) has switchable valves (10,11). 5.Fin according to claim 3, characterized in that the pump (8) is foot-operated. 6.Fin according to claim 1, characterized in that the fluid is gas from a Pressure vessel (20) is used. 7.Fin according to claim 1, characterized in that the displacement is Spring (21) or a rope. 8.Fin according to claim 1, characterized in that the displacement is Rope (A) or a stop. 9.Fin according to claim 1, characterized in that the parts which can be moved relative to one another are sealed by sealing elements (3).