US2171686A - Boat - Google Patents

Description

p 5, 1939. A. J. DAWSON 2,171,686

BOAT

Filed Aug. 10, 1958 center-lin INVENTOR L /WWW J .zzr.

Patented Sept. 5, 1939 rATENT OFFICE BOAT Albert J. Dawson, Sewickley, P a., assignor to Dravo Corporation, a corporation of Pennsyl- Vania Applicatien August 10, 1938, Serial No. 224,102

4 Ciairns.

This invention relates to boats, particularly to barges and other vessels that are towed, and consists in an improved form of skeg for inhibiting and correcting yawing.

Yawing is the nautical term that designates the tendency of a vessel to swing from its course, and in the case of barges yawing designates the tendency for the stern of the vessel to swing laterally from the line of tow.

A skeg consists in a vertical fin mounted be heath the stern of a vessel and extending in general fore-and-aftdirection. In the case of barges the skegs are usually provided in pairs. They are spaced apart laterally of the barge, and arranged symmetrically with respect to the center-line of the hull. When the barge travels truly in the line of tow, the resistance which the skegs offer to the advance of the hull in the water is a balanced resistancebalanced on opposite sides of the center-line of the barge, but when the stern of the barge yaws, the skegs provide an increased drag that is effective on the side toward which stern has swung. Under the influence of such off-center drag, the barge swings back into alignment with the course of travel. Such is the manner in which the skegs operate to correct yawing.

More particularly, the invention consists in a skeg which, by virtue of particular refinements in form and construction, operates with increased ciiiciency in the prevention of yawing, while offering small resistance to the travel of the barge in the line of tow.

An embodiment of the invention is illustrated in the accompanying drawing, in which Fig. I is a fragmentary View, showing in side elevation the stern of a barge equipped with skegs of this invention; Fig. II is a view in end elevation of the stern of the barge; Fig. III is a fragmentary view, showing the stern of the barge in plan from above, and illustrating the skegs in dotted lines.

The reference numeral I designates the stern of a boat, in this case a barge having raked ends, upon which a pair of the skegs 2, 2 of my invention is mounted. The skegs project downward from the raked stern of the barge, and are arranged symmetrically on opposite sides of the longitudinal center-line of the hull. Each skeg is constructed of plate steel, reinforced as need be, and integrated with the hull. The skegs extend in general fore-and-aft direction, and the outboard wall of each skeg flares outward in its extent towards its after edge 3. In accordance with the aims of the invention, the flare of the edge to edge.

wall of the skeg is continuous, and the degree of the flare is so determined that, when the barge travels at normal speed, the water will not break away from the outboard surfaces of the skeg and cause eddying.

In general, the outboard wall of the skeg includes a plurality of vertical wall portions, arranged in fore-and-aft succession and integrated Specifically, such Wall includes two vertical portions 4 and 5, formed of two plates of steel cut to pattern and welded in place. The two plates project vertically downward from the hull, as shown, and the planes of the two plates intersect on a vertical line 6 intermediate the longitudinal extent of the skeg. As viewed in plan, the wall portion 5, extending downward and aft from the hull to the line 6 of intersection, is inclined to the longitudinal center-line of the barge, while the wall portion 4, extending aft from such line of intersection, is inclined at greater angle to such center-line. I have discovered that, to the ends in view, the angle of fiarethe angle a between wall portions 4 and 5should have a value of between and 178, and that in no case should such angle be substantially less than 170. The forward outboard wall portion 5 may extend parallel to the centerline of the boat, although it is preferably inclined, as shown. Ordinarily the angle 1) between such wall portion (5) and the center-line will not exceed 10, and this means, as will be perceived from what has already been said, that the angle 0 between the wall portion 4 and the center-line will be of a value of 20 or less.

The edges of the skeg, fore and aft and below, are of uniform and minimum thickness: they are as sharp as is consistent with ruggedness of structure.

The inboard wall of each of the companion skegs is so particularly shaped as to afford maximum effect to the flare of the outboard surfaces. To such end, the inboard surface, throughout the forward portion of the skeg, extends in parallelism to the center-line of the boat-throughout this portion the skeg surface exerts no disturbing influence upon the free flow of water between the skegs; and throughout the rearward portion the inboard surface flares to meet the after edge of the outboard surface. In embodiment of such characteristics, the inboard wall of each skeg' is formed of two plates 49 and 58 of half-diamond shape, that meet and are integrated on an inclined line 60. The forward inboard plate 50 extends parallel to the centerline of the boat, and, meeting the hull in a line 51, such plate extends downward to the lower edge of the skeg in a plane that is inclined to the vertical. The after inboard wall portion or plate unites the plate with the after edge '3 of the skeg, and it will be perceived that the plate 4!! meets the hull in a line 4| that extends, as viewed in plan (Fig. III), at an angle of approximately 45" to the center-line of the barge.

The plate 40 in this case is not p1aneit is flexed it operates with exceedingly high efliciency in inhibiting and correcting yawing.

I claim as my invention: 7

1. A boat with twin skegs mounted on and projecting downward from its stern, the outboard walls of said skegs extending with outward flare from fore to aft, and the inboard walls of the skegs including each a forward portion extending substantially in parallelism with the centerline of the boat and a rearward portion flaring to the after edge of the skeg.

2. A boat with twin skegs mounted on and projecting downward from its stem, the outboard wall of each skeg including forward and after outwardly and rearwardly flaring vertical wall portions that extend at an angle to one another, the value of such angle lying between and 3. A boat with twin skegs mounted on and projecting downward from its stern, the outboard wall of each skeg including a forward vertical wall portion that extends at an outwardly diverging angle to the center-line of the boat, and an after vertical wall portion that extends angularly outward from such forward wall portion, the inboard wall of the skeg including a forward wall portion that extends in parallelism with said center-line of the boat, and an after wall portion that extends angularly outward from said last-mentioned wall portion to the after edge of the skeg.

4. In a boat having twin skegs mounted on and projecting downward from its stern, with the outer surfaces of the skegs being substantially free from eddy-forming irregularities; the refinement herein described in which the outboard surface of each skeg flares outward in its extent from its forward to its after edge, with the degree of flare increased in the extent of the skeg between such edges.

ALBERT J. DAWSON.

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