JPS60209386A - Movable type skeg - Google Patents

Abstract

PURPOSE:To improve performance of turning by providing a skeg, rotatable round a shaft in parallel to a steering shaft, under the bossing of the stern and operating said skeg as an ordinary one during steering on a fixed course and swiveling the skeg, in case of turning, to provide additional turning force. CONSTITUTION:A skeg 14, rotatable round a shaft nearly in parallel to a steering shaft 2, is provided under the bossing of the stern. During steering on a fixed course, the skeg, as an ordinary skeg, puts restrictions on a current which crosses the stern to improve directional stability. In case of turning, the turning force 16 due to a stern current 5 is generated, through swiveling the skeg 14 similarly to the steering shaft 2. Since the turning force due to the movable type skeg is added at the time of turning, performance of turning can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a skeg mounted on the stern of a ship.

FIG. 1 shows a plan view of a conventional skeg attached to the stern section 1. The skeg 4 attached to the stern is intended to restrict the flow across the stern during a turn and improve course keeping and directional stability of the hull 1.

This is because the skeg 4 acts as turning resistance when the hull 1 turns, thereby improving the directional stability of the hull.

However, when the conventional skeg 4 is installed, the turning resistance increases and the directional stability which is the original function increases, but on the other hand,
When it is necessary to turn the ship as quickly as possible due to this increase in turning resistance, there is a drawback that turning performance is deteriorated.

This can be explained using Figure 1, which shows the movement of the right arm.
When the hull 1 is induced to turn slightly due to disturbances such as wind and waves, the stern flow 5 that follows this flows into the skeg 4 from the port side.This stern flow 5 causes the skeg 4 to
A force β acts on the skeg in a direction that pushes the stern from port to starboard. This is a moment that prevents the turning movement of the starboard arm of the hull 1, and the skeg 4 improves the directional stability of the hull.

On the other hand, when the rudder 2 is operated to induce a turning movement, the hull 1 starts turning to the starboard 1 by the rudder cuff, and the stern flow 5 flows into the skeg 4 from the port side. Therefore, a force 6 acting on the skeg in a direction that pushes the stern from port to starboard acts on the skeg 4. This is equivalent to the direction opposite to that of the rudder cuff and the turning force due to the rudder cuff being reduced. For this reason, ships equipped with the skeg 4 generally have a disadvantage in that their turning power is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-described problems of the conventional skeg, and to provide a skeg that acts as turning resistance during course keeping and generates turning force during turning.

Therefore, the movable skeg of the present invention is characterized in that a skeg rotatable about a shaft substantially parallel to the rudder shaft is provided below the stern bossing.

The movable skeg of the present invention will be explained below with reference to the drawings. FIG. is attached to the lower part of the propeller bossing 8 on a rotating shaft 18 parallel to the rudder shaft. This figure shows the state during course-keeping maneuvering, and the movable skeg 14 is oriented perpendicular to the water surface and acts as a turning resistance when turning.

FIG. 3 shows a state in which the rudder 2 is being operated during a turn (3). The movable skeg 14 is in a state of being rotated about the size of the rotating shaft 18, and its direction is the same as the rudder angle.

The action of the fluid force at this time will be explained with reference to FIG. 4, which shows the turning motion of the starboard. The stern flow 5 is flowing in from the port side of the ship. The rudder cuff is working to push the stern from starboard to port, creating a starboard snarl moment. On the other hand, regarding the skeg 14, there is also a force 16 acting on the skeg that pushes the stern from starboard to port, which also generates a starboard turning moment, and as a whole, the effect when the skeg 14 is also operated is greater than when the rudder 2 is used alone. The turning force increases.

Since the conventional skeg 4 is fixed to the hull as shown in FIG. 1, when it is desired to actively turn the hull 1, this type of skeg 4 acts as a turning resistance and reduces turning performance.

As shown above, the movable skeg of the present invention has a structure that allows it to rotate under the weight of an axis that is almost parallel to the rudder axis, and acts as a normal skeg (4) during course-keeping maneuvers, and when turning, this axle weight is used. By rotating the rudder in the same direction as the rudder angle, the movable skeg generates lift and the turning force of the movable skeg is added to the turning force of the rudder, so it is possible to maintain course without reducing turning performance. Performance can be improved. Furthermore, if you want to stop the turning movement even after the turning movement has been induced, there is an advantage that in addition to steering, you can adjust the angle of this movable skeg to act as turning resistance and quickly stop the turning movement.

That is, the movable skeg of the present invention has the effect of making it possible to improve both course-keeping performance and turning performance.

[Brief explanation of drawings]

FIG. 1 is a plan view of a hull equipped with a conventional skeg. FIG. 2 is a perspective view of the stern section of a hull equipped with a movable skeg as an embodiment of the present invention, and a plan view of the hull equipped with a second movable skeg. ■... Hull, 2... Rudder, 3... Propeller, 4...
・Skeg, 5... Stern flow, 6... Force acting on the skeg,
7... Rudder force, 8... Bossing, 14... Movable skeg, 16... Force acting on the movable skeg, 18...
Axis of rotation

Claims (1)

[Claims] A movable skeg characterized in that a skeg rotatable around an axis parallel to the rudder shaft is provided below the bottoming of the stern.