US2198295A - Antirolling device for ships - Google Patents

Description

Patented Apr. 23, 1940 UNITED STATES 2,198,295 ANTIROLLING DEVICE FOR. SHIPS Wilhelm H. C. E. Riisingh, Schiedam, Netherlands, assignor of one-half to N. V. Wiltons Machinefabriek en Scheepswerf, Maatschappij Voor Scheeps-en Werktuigbouw Fijenoord N. V., Schiedam, Netherlands, a Netherlands manufacturing company Application November 8, 1937, Serial No. 173,517 In the Netherlands November 11, 1936 1 Claim.

This invention relates to antirolling devices for ships. Its primary object is the provision of simple means approximating the effect of gyroscopes, antirolling tanks and other costly and cumbersome devices, that is to say, imposing a much greater resistance to rolling action than do ordinary bilge-keels,without,however, presenting the well-known disadvantages of said devices.

In accordance with the invention, the ship is fitted on each side and below the water line with a series of a large number (at least twenty) laterally projecting and suitably spaced vanes rigidly secured thereto and having stream-line formed cross-sections, the length of each vane,

5 measured athwart-ships, exceeding the width as measured longitudinally of the ship.

Conveniently,said vanes will be fitted to the bilge in the region where ordinary bilge-keels, which extend continuously over a substantial portion of the length of the vessel, are usually provided, but in some cases it may be advisable to place them elsewhere, for instance, in the case of a tug having exceptionally heavy wales.

The appended drawing illustrates preferred exemplary embodiments of the invention.

Fig. 1 is a side-elevational view of a ship provided with the novel antirolling-means, and

Fig. 2 is a cross-sectional view of said ship.

Fig. 3 is a plan view, on an enlarged scale, of part of a somewhat modified embodiment, the hull of the vessel being shown in section.

Fig. 4 is a cross sectional view taken along the line li of Fig. 3; and

Fig. 5 is a view corresponding to Fig. 1 but 35 showing a modified relationship of parts.

The ship I is provided on either side with a multiplicity of fixed antirolling vanes 2 structurally connected therewith and adapted to steady it, i. e., to reduce its rolling as it moves through 40 rough water. In addition, it is fitted on each side with fore and aft series of fixed vanes 4 and 3 for counteracting the tendency of the ship to pitch.

Said vanes are fitted in such a manner as to present least possible resistance to the flow of 45 the water along the ship, and are spaced apart at such intervals that the action of the one is no impaired by that of the other.

In accordance with Fig 2, the free ends of the vanes of each series are interconnected by a plate 5 substantially parallel with the hull surface, the

ends of said plate being secured to the ship hull.

When the ship is moving ahead and simultaneously rolling, pitching or heaving, the said vanes, the cross-section of which is shown in Fig. 3, will assume inclined positions relative to the direction of the water flow, thus inducing a high transverse force tending to steady the ship.

The favorable action of the novel means is due to the fact that the length-to-width-ratio of the vanes exceeds unity. Short vanes having a relatively great width have a very low efiiciency, since the eddy currents set up at the free ends thereof reduce to almost zero the effect of the inclination of the vanes relative to the direction of movement of the water flowing past.

It will thus be understood that with vanes in accordance with this invention flow caps are, to a certain extent, redundant. Therefore, Fig. 3 shows a construction wherein the free ends of the vanes 2 are simply braced by a relatively thin rod '1 of circular cross-section, the ends of said rod being secured to the hull.

Since the effect of the vanes is due to the rolling and to the speed of the forward (or backward) progress of the ship, it will be low when the amplitude of the oscillations is small. Oscillations of large amplitude, however, i. e., those oscillations, which are particularly unpleasant for passengers and other occupants of the vessel and which, in the case of warships, result in very unsteady gun platforms, will be damped effectively.

In practice it has been found that the novel anti-rolling means can increase the damping factor by 100 to 200%.

Stream-lined vanes to be used for the purposes of this invention are easy to make, for instance, by planing a steel plate and thereafter cutting the planed plate into sections of the required lengths. Preferably, they are secured to the ship hull (and the braces 5 or 1 aresecured both to the free ends of the vanes and to the ship hull) by welding operation.

It may sometimes be desirable to provide the ship with two vertically spaced rows of antirolling vanes, and in that case the vanes of the one row will preferably be placed in staggered relation to those of the other, as shown for example in Fig. 5.

What I claim is:

A ships hull provided at each bilge with at least twenty fixed antirolling vanes of streamline form and having a length, measured athwartships, considerably in excess of their width, measured longitudinally of the ship, the vanes having invariable cross sections in all planes perpendicular thereto.

H. c. E. nosmen.

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