US968927A

US968927A - Means for preventing the rolling of ships.

Info

Publication number: US968927A
Application number: US44359708A
Authority: US
Inventors: Hermann Frahm
Original assignee: Individual
Current assignee: Individual
Priority date: 1908-07-15
Filing date: 1908-07-15
Publication date: 1910-08-30
Anticipated expiration: 1927-08-30

Description

H. FRAHM.

MEANS FOR PREVENTING THE ROLLING 0F SHIPS.

APPLICATION FILED JULY 15, 1908.

968,927. Patented Aug. 30,1910.

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UNITED STATES PATENT omuon.

HERMANN FRAHM, 0F HAMBURG, GERMANY.

MEANS FOR PREVENTING THE ROLLING OF SHIPS.

T 0 all whom it may concern:

Be it known that I, ll ERMANN FRAi-IM, a citizen of the free town of Hamburg, and resident of 1S Kloster Allee, of the free town of Hamburg, in the German Empire, engineer, have invented certain new and useful Improvements in Means for Preventing the Rolling of Ships,.of which the following is a specification:

This invention relates to means used for damping the rolling motion of ships by employing water tanks therein in which the periodic motion of the water when the ship rolls is utilized to counteract the rolling of the ship.

It has already been proposed to counteract the rolling of ships by providing a double hull arranged so that the two walls of the hull were at a greater distance apartat the bottom of the ship than at the sides. The outer hull was at the bottom provided with holes so as to place the space between thehulls in communication with the outer water. ith this construction the bulk of the water is arranged at the bottom of the ship and its action as regards damping the rolling motion is more in the nature of a heavy keel. I The result of this is that the rolling motion is not very efiiciently damped but merely the period of oscillation of the ship lengthened.

According to the present invention I propose to employ tanks arranged at the sides of-the ship and connected to the outer water by pipes of smaller cross section than the tanks themselves. The cross section of the connection pipes is so dimensioned as to cause the periodic motion of the water in and out of the said tanks during rolling of the ship to correspond as nearly as possible with the calculated periodic motion of the ship during rolling, assuming that the pressures above the water in the tanks on both sides of the vessel are maintained equal,-

for instance by constantly exposing the water in the tanks on both. sides to atmospheric pressure or in the case" of closed tanks by providing for instance a cross connection between the top of the tanks. The

construction which I preferably employ conable means being provided for maintaining.

Specification of Letters Patent.

Application filed July 15, 1908.

Patented Aug. 30, 1910. Serial No. 443,597.

equal pressure above the water in opposite chambers for instance by a pipe connecting the upper ends of the chamber. In practice however owing to the well known fact that each vessel develops an unforeseen rolling motion peculiar to itself and owing to the constantly varying conditions under which a vessel travels, it is found desirable to provide means for Varying the lag in the flow of water in the tanks or chambers. This variation may be obtained either by throttling more or less the flow of water through the connection to the sea or by varying the flow of air between the spaces above the water levels in the opposite tanks or chambers For special purposes it is sometimes necessary to get the water levels in both tanks into a different height in relation to the outer sea. A suitable device for this is to control the degree of pressure or vacuum above the Water levels in the chambers and a simple method is to connect the cross air pipe with a pressure or vacuum pipe.

The invention will be more readily understood from the following description of the apparatus illustrated in the accompanying drawing which is a diagrammatic cross section through a ship provided with antirolling chambers according to the present invention.

In the drawing the chambers m and n on each side of the ship are connected by pipes at and r respectively with the water in which the vessel is floating. The chambers are shown as provided with tapering sides which has the effect of enabling the period of the oscillations to be regulated in a manner de scribed in a co-pending patent application, filed by me. The opemng to the sea Water is also tapered at s to prevent shocksor undue friction. The upper ends of the vessels m and n are connected by means of a pipe 0 in which a valve 0 is arranged to effect throttling to control to some extent the pe-' riod of oscillation of the water in and out of the chambers m and n. As can be seen from the figure the outer water is higher than the water in the vessels during the nor- 4 mal position of the ship and in consequence the air in the vessels m and n is in thls-case subjected to an initial pressure equal to the head of water 72. It will also be seen that in this case the quantities of water are alternately greater on each side during-rolling of the boat. During rolling the transference of the bulk of the weight from one side of the boat to the other takes place periodically out of phase with the rolling of the boat.

There are thus two periodic motions seta ainst one another and thereby a balancinge ect is obtained.

I claim 1: Apparatus for damping the rolling motion of ships having withln the ship, a

vertical chamber at each side of the ship, said chambers being widened upwardly and connections from the bottom end of each of said chambers to the sea Water, said chambers and connections being so dimensioned that the periodic oscillations of Water in and bers to the sea water, said connections and chambers being so pro ortioned that the period of oscillation of t e water in and out of the chambers is substantially equal to the.

natural period of oscillation of the ship, and means for regulating the degree of vacuum or pressure in the upper ends of said vertical chambers.

3. Apparatus for damping the rolling motion of ships having within the ship, a

vertical chamber at each side of the ship, said chambers being closed at their upper ends, connections from each of said chambers to the sea water, said connections and the chambers being so proportioned that the period ofoscillation of the water in and out of the chambers is substantially equal to the natural period of oscillation of the ship, a pipe joining the upper ends of the vertical chambers on each side'of the ship and a valve in said pipe.

4. Apparatus for damping the rolling motion of ships having within the ship a vertical chamber at each side of the ship, said chambers being widened upwardly and closed at their upper ends, connections from the bottom end of each of said chambers to the sea water, said chambers and connections being so dimensioned that the period of oscillation of water in and out of said vertical chambers is substantially equal to the natural period of oscillation of the ship, a pipe joining the upper ends of the vertical chambers at each side of the ship and a valve in said pipe.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

HERMANN FRAHM.

Witnesses ERNEST H. L. MUMMENHOFF, O'r'ro W. HELLMRICH.