US2213611A - Boat propelling and stabilizing apparatus - Google Patents

Description

2 Sheets-Sheet l A. RONNING BOAT PRQPELLING AND STABILIZING APPARATUS Filed May 9, 1958 Sept. 3, 1940.

l .41 ATTORNEY /5 INVENTOR Apu PH /eo/wv//v 115. MARNE PROPULSiON. Search Rmom Sept 3 1940- A. RoNNlNG 2,213,611

BOAT PROPELLING AND STABILIZING APPARATUS vman may 9. 195s 2 sheets-snm 2 llvl Patented Sept. 3, 1940 UNITED STATES Search 2,213,611

PATENT OFFICE BOAT PROPELLING AND STABILIZING APPARATUS Adolph Ronning, Minneapolis, Minn.

Application May 9, 1938, Serial No. 206,817

8 Claims.

My invention relates to apparatus for the propulsion and stabilization of boats and water craft of various kinds.

The primary object of my invention is to provide a boat or ship propulsion apparatus or assembly wherein a plurality of separate propeller units are arranged in fore and aft and laterally spaced positions beneath the hull of the ship, and wherein each propeller unit is separately and independently driven to facilitate control of the movements of the ship.

Another object is to provide a propulsion apparatus of this character wherein fore and aft propeller units are arranged for oscillation about vertical axes to thereby vary the angles at which. the thrust of the propellers is directed and enable the ship to be propelled forwardly, rearwardly, laterally or in any intermediate direction, to thus facilitate control of the ship and permit its being docked without the use of tugs, as required at present.

Another object is to provide a propulsion apparatus as described wherein a propeller unit is mounted at each side of the ship, substantially amidships, and spaced outwardly from the keel line. The propeller units are then arranged to be oscillated in vertical and fore and aft planes to thus tilt the propeller axes upwardly on one side of the ship and downwardly on the other side, or vice Versa, whereby an upward thrust will be given to one side of the boat While a downward motion will be applied tothe other side. As a result, the boat may be stabilized against the usual rolling motion encountered in heavy seas, and the normal downward roll of either side of the ship may be counteracted by an upward thrust on that side by proper positioning of the propeller units. The propeller units meanwhile add their bit to the forward driving motion of the ship to keep it on its course.

Another object is to provide control means for actuating and manipulating the propellers in the manner described for stabilizing the ship, and which control means accomplishes this operation entirely automatically under influence of the normal rolling movements of the ship, in order thus to compensate properly for these movements and prevent undue rolling of the ship in even the heaviest seas.

Another object is to provide means for adjusting the axis of rotation of the fore and aft propeller units, not only about a vertical axis as described, but also in a vertical plane whereby they may be tipped upwardly or downwardly to exert their thrust angularly and so to stabilize the ship in a fore and aft direction and prevent the so called pitching of the ship. Thus the aft propeller may be adjusted to bring about a downward, as well as forward, thrust when the ships stern has a tendency to rise, and Vice versa. The forward or fore propeller unit effects a similar but opposite result in order to hold the bow of the ship in proper line.

A further object is to provide an effective means for rotating the fore and aft propellers about their vertical axes to thus provide for steering the boat, and which steering means may be remotely controlled from the bridge or other steering station in the ship.

A further object is to provide a novel and advantageous form of propeller mounting in which each propeller is mounted in and depended from its individual caisson or bell which is in turn mounted in a well or housing formed in the bottom of the ship so that said propeller depends below the ship bottom to enter the water. These caissons are then arranged to be oscillated or tipped in Vertical planes to bring about the aforesaid angle control of the thrust direction, and the caissons are furthermore so arranged as to be readily removable from their wells for repairing any of the propellers without moving the ship into dry dock.

A further object is to provide a propulsion apparatus for ships and which employs a plurality of propellers as described, and in which each propeller may be conveniently powered or driven by its individual drive unit, engine, or motor so that any one or more of these propeller assemblies may be taken out of commission for repairs or other purposes without seriously disabling the ship.

Still another object is to provide automatically operating means for indicating, at a remote point such as the bridge, the angular position in which the steering or fore and aft propellers are operating, to thus facilitate the steering and control of the ship.

Stii'a further object of the invention is to provide a ship propulsion apparatus of the foregoing characteristics in which certain of the propellers may be mounted in recesses or openings out in the keel of' the ship in such manner that the keel will serve as protection for the propellers against obstructions in the water.

The foregoing and other objects, together with means whereby the same may be carried into effect, will best be understood from the following description of my invention, reference being had Room therein to the accompanying drawings, where- Fig. l is a side elevation of a ship equipped with my propulsion and stabilization apparatus.

Fig. 2 is a fragmentary, longitudinal, enlarged and vertical section through either the fore or aft propeller assemblies shown in Fig. 1.

Fig.'3 is a vertical, transverse section along the line 3 3 in Fig. 2.

Fig. 4 is an enlarged, longitudinal, vertical section through one of the amidships propeller assemblies, shown in Fig. 1.

Fig. 5 is a transverse, vertical section along the line 5-5 in Fig. 4.

Fig. 6 is a view similar to Fig. l, showing a modified arrangement or mounting for the propeller assemblies.

Fig. 7 is an enlarged, fragmentary, transverse and vertical section along the line 'I--l in Fig. 6.

Fig. 8 is an enlarged, fragmentary, transverse and vertical section along the line 8-8 in Fig. 6.

Fig. 9 is a fragmentary, sectional view along the irregular line 9 9 in Fig. 8.

Fig. 10 is an enlarged, horizontal and diametrical section along the line Ill-I in Fig. 'l'.

Referring now more particularly to Figs. 1 through of the drawings, the reference character A designates a ship or boat which may be of any size, style, or type, and in connection with which I employ the propeller assemblies or units designated generally at B, C, D, and E, which are, of course, of a size commensurate with the size of the ship A. These propeller assemblies are arranged, in the particular construction shown, with one located near the rear of the boat, one near the bow, and two in transverse alignment substantially amidships, but it is to be understood that additional assemblies may be used if found desirable. The propeller assemblies are hereinafter referred to as the aft steering assembly B, the fore steering assembly C, and the midship balancing or stabilizing assemblies D and E.

The ship A has the usual hull F of suitable construction, the upper or deck structure G, and the longitudinally and centrally extended keel K along its bottom. The aft propeller assembly will be first described, and the same comprises the propeller head or blade unit I0 and the drive unit or motor II which is supported above the blade unit and above the tubular standard I2. It may here be noted that the blade unit or propeller head I0, together with its transmission housing I3 and guardwliimare of the type disclosed and claimed in my copending application for United States patent on boat propulsion apparatus Serial No. 204,061, filed April 25th, 1938, and to which reference is invited for details of this assembly. It is sufficient to set forth herein that the propeller unit comprises a frontal propeller I5 and rear propeller I6, eacl"'fvhih/"incdes a water conflningguard rim Il, and which are driven in eitri'ethe s'a.rneor"pposite directions by suitable transmission gears (not shown) in the housing I3, and by the drive shaft I8 which depends from the drive unit II downwardly through the standard I2. The advantages of this specific propeller arrangement set out in the application above identified make it Well suited for use in the present apparatus, but it will, of course, be understood that any other suitable propeller may be used as desired.

The ships hull F is provided with a well or housing I9 which extends some distance above the water line of the ship, and is located in the aft part of the hull at the center thereof. This well I9 has the upper portion or wall 20, and the curved lower end 2I which has the longitudinally elongated central opening 22. The keel K has a rectangular opening 23 cut below the Well I9, and these two openings 22 and 23 communicate as shown. The propeller unit is mounted in a caisson or bell housing 24 which is of smaller diameter than the well I9, and has a rounded lower end 25 which may rest against the rounded lower end 2I of the well. The standard I2 is mounted and journaled vertically through the rounded lower end 25 of the caisson 24, and is retained in place by a water tight gland assembly 26. The propeller unit I0 thus depends into the opening 23 in the keel K, which affords sufficient clearance for the unit, and the drive unit II is supported within the caisson so that it is protected from the water. It will be noted that the water may penetrate and enter the well I9 around the caisson 24 through the opening 22, but this is of no disadvantage since the water will not rise above the open upper end of the Well and cannot reach any working or driving parts within the caisson. The upper end of the caisson may be open, as shown, to facilitate repair or inspection of the drive unit II and other parts therein.

The caisson 24 is retained in place in the well I9 by trunnion pins 2l which are located in transverse alignment, and on the center from which the radii of the rounded ends 2I and 25 are determined. It will be noted that these ends are rounded only in a fore and aft direction, and transversely they are only slightly curved to blend nicely into the contour of the hull F. The trunnion pins 2'I are screwed inwardly through tubular members 28 secured to the side walls of the well I9, and their inner ends enter sockets 29 on the sides of the caisson so that the pins will serve as bearings on which the caissons may oscillate or rock, but in such manner that water cannot enter around the plns.

Normally these pins 2l will retain the caisson in the well, but by unscrewing them until they clear the sockets 29, the caisson is freed and may be lifted out of the well I9 by the ship-s boom or other lifting device. It is thus possible to entirely remove the drive and propeller assembly for repair or replacement without dry docking the ship.

The clearance 3D afforded between the upper wall portions of the well I9 and caisson permits the caisson to be oscillated or rocked in a vertical plane and in a fore and aft direction about an axis defined by the trunnion pins 2l, and this action may be carried out automatically and mechanically by a means now to be described. It will be evident that no lateral movement of the caisson is desired or possible, and for this reason the side walls of the caisson and well I9 has a relatively tight but slidable t, as clearly shown in Fig. 3.

Hydraulic cylinders 3I and 32 are secured to both front and rear walls of the well I 9, and have plungers or rams 33 and 34 which extend slidably into the interior of the Well through openings in the walls in line with the bores of the said cylinders. These plungers 33 and 34 carry rollers 35 at their inner ends which bear against the adjacent front and rear walls of the caisson 24 in such manner as to exert a pressure on the caisson in horizontal planes, and near its upper end,

1|I/5/MARINE PROPIS'OI.

when hydraulic pressure is applied to the plungers. For this purpose a pump or pressure unit 36 is provided, and is connected by pipes or lines 31 and 38 to the cylinders 3| and 32 in such manner that, as the pump operates in one direction, pressure will be applied to one cylinder while, as the pump direction is reversed, pressure will be applied to the opposite cylinder. A reversible electric motor 39 is employed for operating the pump 36, and this motor is controlled by a mercury switch unit 4U connected between the motor and its energizing source 4I so that in one position of the switch the motor will rotate in one direction, while in another position the motor will be reversed.

The drive unit II may be an electric motor, as shown, or may be a combustion engine of any kind, as may be desired. In the latter case the exhaust gases, cooling water, and other waste products' may beyeryefncientiydischarged'or exhaustedhrou'gh or nearv th'axis of rotation of thidpellers I5 and- IS, by any of the structures sit-Iimylerebfre identified copending application, as well as another of my applications, Serial No. 202,258, which was led April 15th, 1938. Reference is invited to these two applications for details as to the exhaust means. The drive unit I I is rigidly supported in the caisson 24 by brackets 42 secured to its side walls, and is connected by a coupling 43 to the aforesaid drive shaft I8. However, the standard I2, and of course the shaft I8 and connected propeller head I0, are all journaled for rotation about a vertical axis through the lower end of the caisson, as clearly shown. A large worm gear 44 is secured to the upper portion of the standard I2, and is engaged by a worm pinion 45 which is journaled in a bracket 46 secured to the caisson wall and is driven by a reversible electric steering motor 41. A transversely extended bracket 48 secured within the caisson 24 serves as a bearing support for the gear 44 and standard I2 to prevent axial displacement of the latter, and also has an extended arm 49 which rigidly supports the steering motor 41. This motor may be controlled by a reversing switch (not shown), from any remote point such as the bridge or control room of the ship.

In operation, and with the ship riding at an even keel and moving forwardly, the propeller assembly B stands in the position shown in the drawings and, as the propellers I5 and I6 rotate, they drive the ship forwardly as will be understood. Now, should it be desired to drive the ship laterally, rearwardly, or to any intermediate angle, the steering motor 41 is operated from the bridge or other remote control point, to rotate the standard I2 about its vertical axis and turn the propeller unit III to the desired direction upon which the thrust of the propellers I5 and I 6 is exerted in the selected direction. It is thus possible to steer the ship without the usual rudder, or in connection therewith, and also to navigate the ship in any direction for docking or other purposes.

The mercury switch 40 is so located and arranged that, as the ship tilts or pitches forwardly, tending to raise its stern from the water, the motor'39 will be automatically energized, causing it to rotate the pump 36 and se't up a hydraulic pressure in the rear cylinder 32. This action urges the rear plunger 34 forwardly, causing it to push the caisson 24 and rock or tilt the same forwardly at its upper end. As a result, the propeller unit I0 is tipped or rocked to a forwardly and downwardly inclined position so that it will Search exert a downward pull upon the stern of the ship and overcome this tendency of the stern to rise. Should the stern have a tendency to settle in the water the mercury switch 40 automatically reverses the motor 39, causing a pressure to be set up in the frontal or forward cylinder 3| and urging the plunger 33 rearwardly to so rock the caisson 24 that the axis of rotation of the propellers I5 and I6 will be tipped upwardly in a forward direction. An upward motion is thus imparted to the ships stern, overcoming its tendency to settle. 'I'he aforesaid upward and downward thrusts of the propellers, when thus rocked on their axes in a vertical plane is, of course, in addition to their normal straightaway driving thrust so that the ship is maintained on its course. The mercury switch 40 is thus seen to be responsive to rocking or pitching motion of the ship about its longitudinal axes, and serves to so control the motor and pump assembly that this pitching motion will be, in great part at least, eliminated, and the ship will be much more stable in even the heaviest seas.

The frontal or fore steering propeller assembly C is identical in construction and operation to the aft assembly just described, with the single exception that the mercury switch controlling its pump and motor is oppositely set so that it rocks the frontal propeller unit upwardly at its forward end, while the rear propeller unit is being rocked downwardly at its forward end. As a result the normal depression or dipping motion of the bow of the ship, as its stern rises, will be compensated for by the frontal or fore propeller unit, and the propellers thus work in unison at all times to stabilize the ship against pitching action. This fore propeller assembly C also aids in the steering of the ship, and may be independently controlled for this purpose if so desired. In fact such independent control, either at all times or selectively. would be of advantage in maneuvering the ship since either end could be moved in any desired direction.

The keel K will act as guards for the fore and aft propeller units B and C, since they are located in openings formed in the keel, and the propellers will thus be protected from obstructions in the water. This arrangement has the further advantage of reducing the draft of the boat since no projections whatever are formed below the keel.

The midship balancing or stabilizing propeller assemblies D and E are each identical in construction, and are quite similar to the aft assembly B so that only the major parts need be described. These assemblies D and E are arranged mldships, or substantially so, in transverse alignment, and are spaced outwardly some distance from the keel K. These assemblies comprise the wells 50-5I which have their rounded lower ends 52-53 opening out beneath the ship through the fore and aft elongated openings 5f 55. The caissons 56-51 are mounted by their rounded lower ends 58-59 in the wells, and carry the drive units Bil-5I which are supported within the caissons atop the standards 62-63. These standards are, in this case, rigidly secured to and through the bottoms of the caissons and carry the propeller units 64-65 without any provision for rotation about a vertical axis. The units 64--65 are thus so arranged that they drive the ship forwardly at all times but, if desired, they may be arranged for reversing when the ship is moving rearwardly and may be completely disabled or dis- Room connected when the ship is being moved to either side.

The caissons 56-51 are rockably mounted in the wells Sli-5| upon trunnion pins `66-6'l-E8, the outer two of which are extended inwardly through the outer walls of the wells, while the center one penetrates the single parting wall of the well, as here shown, and supports both caissons at that point. Otherwise the construction and arrangement of these pins is identical with the pins 27 hereinbefore described. However, the wells 50-5l might in actual practice be spaced substantially apart, in which case a pair of trunnion pins would be employed for each caisson.

The caissons 56-51 are thus so arranged that they may be rocked in a vertical and fore and aft extended plane on their trunnion pins, and each may move independently of the other. In actual use the caissons are always oppositely moved, and this action is automatically brought about by means now to be described.

Hydraulic cylinders (iS-1D are mounted in the front and rear walls of both wells Ell-5l, and plungers ll-'l2 are slidably mounted in the cylinders with their inner roller ends in contact with the front and rear walls of the caissons 56--51 near their upper ends. A pump or hydraulic pressure unit 13 is provided, and is connected by lines 'i4-l5 to the frontal cylinders 69, while the rear cylinders l are cross connected by a line 16. A reversible electric motor 'l1 is connected to the pump 13, and is controlled by a mercury switch unit 18 connected between the pump and its electrical source of supply 19.

The switch unit 18 is so arranged that Should the ship roll or tilt downwardly on the left hand, or port, side, the motor 11 will be operated to rotate the pump 13 and cause pressure to be exerted against the plunger 'H on the frontal left side. The left hand or port caisson 56 will thus be rocked rearwardly, causing the propeller unit 64 to tilt upwardly and forwardly, as shown in Fig. 4. The pressure in the rear port cylinder 'IFJ caused by rearward motion of the plunger l2, will cause a forward pressure to be exerted (through the line 16) on the right hand or starboard rear plunger so that the starboard caisson 51 will be rocked forwardly, and the forward end of its propeller unit 65 will be moved downwardly, also as shown in Fig. 4. The result of this action is to cause an upward motion or force to be applied on the port side, while a downward motion is applied to the starboard side to thus compensate for, and prevent, this roll to port which would otherwise occur. Then should the ship start to roll to the starboard side, the caissons will be rocked in the opposite direction by reversal of the motor TI by the switch 18, and an upward force will be applied in a starboard side while a downward force is applied to the port side to prevent this roll. The mercury switch is thus responsive to rolling or transverse tipping motion of the ship, and the ship is now stabilized against both fore and aft and transverse motions in the sea.

The propeller assemblies D and E are preferably spaced outwardly from the keel K some distance, as shown, in order that they may exert a maximum leverage on the ship to prevent said rolling motion.

Referring now to Figs. 6 through 10 of the drawings, it will be seen that I have provided a modied construction in which all of the propeller assemblies B', C', D', and E are rigidly mounted in the ship A insofar as any tilting or rocking motion is concerned. In other particulars the construction and arrangement is quite similar to that hereinbefore described, and the aft steering assemblies B will be first described in detail.

This assembly B comprises the `propeller or blade unit lila, drive unit Ha, and standard |22' arranged exactly as hereinbefore described. The hull F has a well I9d formed in its after, central portion, and this well has the open lower end 22a communicating with an opening 23a cut in the keel K. A caisson 24la is mounted in the well 19"1 and is retained therein by an outwardly turned flange 80 on its upper end which overhangs the upper edge of the well. The standard I 2a is journaled vertically through the bottom 25a of the caisson 2lia through the watertight gland 26e so that the propeller unit l0a depends into the opening 23a in the keel while the drive unit Ila is protected within the caisson.

A worm gear 44a is affixed to the standard l2a within the caisson and bears against a transverse bearing bracket I8a while a worm pinion ial meshes with the gear and is driven in either direction by a reversible steering motor 41a so that the propeller unit Ilia may be rotated about a vertical axis for steering the ship, as aforesaid.

In order to indicate to the operator of the steering controls the exact angular position of the propeller unit I0, Igprovide -theindcator mechanism SLL* This may be of a well known type in which a metal member is moved through a magnetic field to thereby cause a variation in a current flowing in al circuit including a meter which is calibrated to indicate the position of the metal member. Therefore, a cam 82 is mounted on the standard l2a to turn therewith and engages the metal field member 83 to move the same toward or away from the standard as the same rotates. The meter 84 is located in any desired remote point in the battery or energizing circuit 85, and, as the standard rotates and moves the member 83, the meter reading will be correspondingly varied. The meter may then be calibrated to read in angular directions between forwardly and rearwardly positions of the propeller unit lila, and so indicate exactly and at all times the position thereof. This indicating means may also be used in all of the propeller assemblies B, C, and C as well, and adds considerably to the flexibility of operation and makes it possible for the pilot or operator to so set the propellers at a slight angle to compensate for drift in currents running transversely to the direction of travel of the ship.

The forward propeller assembly C is identical with that just described, and needs no further description herein.

The midships propeller assemblies D and E are identical in construction and arrangement, and include the caissons SGL-57a mounted in the transversely aligned wells 50e-Sla and carrying the drive units 60e-Sla, the propeller or blade units lilla-65a and connecting standards S23-63a, which in this case are rigidly mounted through the bottoms 5821--59a of the caissons. The caissons 5ba- 51a are removable from the wells, being in this case provided with hooks 86 for this purpose, and the bottoms 581--59ab are shaped to iit nicely into the contour of the bottom of the hull F. The keel K carries stop plates 81 which engage the inner and lower edges 88 of the caissie iw. wmnINt FHUPU RNW.

son bottoms, and so retain the caissons in place in the wells 50a-Sla. The caissons are further retained in. place and prevented from vibrating by set screws 89 which are threaded through the Walls, and may be adjusted to bear outwardly against the walls of the wells, as shown.

The above structure operates exactly as does that described hereinbefore in some detail. and no further description should be required herein.

It is understood that I may make variations in the specific structures herein described, so long as such variations fall within the spirt and scope of the appended claims. Having now therefore fully disclosed my invention, what I claim as new and desire to secure by Letters Patent, is:

1. An apparatus for propelling and stabilizing a ship, comprising a well formed in the ship and opening downwardly therebeneath, a caisson member removably mounted in the well and supported for oscillation in a vertical and fore and aft plane therein, means operable against the sides of the caisson member for oscillating it within the wells, and a propeller unit mounted in the caisson member and having its blade device depended below the Well.

2. An apparatus for propelling and stabilizing a ship, comprising a well opening downwardly through the hull of the ship and over the keel thereof, the said keel having an opening, a caisson member mounted in the well and upwardly removable therefrom, means for retaining the caisson against downward displacement from the well, a propeller unit rotatably mounted vertically through the bottom of the caisson member and having its blade device extended into the opening in the keel, and means for rotating the propeller unit about its vertical axis whereby the horizontal angle of thrust may be varied 'for steering the ship.

3. An apparatus for propelling and stabilizing a ship, comprising a well opening downwardly through the hull of the ship and over the keel thereof, the said keel having an opening, a caisson member mounted in the well and upwardly removable therefrom, means for retaining the caisson against downward displacement from the well, a propeller unit rotatably mounted vertically through the bottom of the caisson member and having its blade device extended into the opening in the keel, means for rotating the propeller unit about its vertical axis whereby the horizontal angle of thrust may be varied fonA steering the ship, andnmeans for visually and re-` motely indicating the relative angular position oi,

the propeller unit about its vertical axis.-

4. An apparatus for propelling and stabilizing a ship, comprising a well formed in the ship and opening downwardly through the bottom thereoi', a caisson member oscillatably supported in the well with bearing engagement with the bottom thereof, the said well and caisson member having straight sides parallel with the plane in which said member oscillates, means operable on the other walls of the caisson member for os- Search Hoon.

cillating the member, and a propeller unit suspended in and through the caisson member.

5. In an apparatus for stabilizing a ship, the same including a housing opening downwardly through the hull, a caisson member mounted in the housing for rocking movement about a substantially horizontal axis, a propeller unit rotatably mounted on a substantially vertical axis through the bottom of the caisson member and having its blade device suspended beneath the downwardly opening end of the housing, means for rotating the propeller unit about its vertical axis for steering and propelling the ship, and means operable against opposite sides of the caisson member for rocking the same about said horizontal axis.

6. In an apparatus for stabilizing a ship, the same including a housing opening downwardly through the hull, a caisson member mounted in the housing for rocking movement about a substantially horizontal axis, a propeller unit rotatably mounted on a substantially vertical axis through .the bottom of the caisson member and having its blade device suspended beneath the downwardly opening end of the housing, means for rotating the propeller unit about its vertical axis for steering and propelling the ship, hydraulic means operable against opposite sides of the caisson member for rocking the same about a, horizontal axis, and said hydraulic means includ-f inga' automatic control for rocking the caisson member in accordance with the inclination of the ship.

7. Apparatus for propelling and stabilizing a ship of the type having a hull and longitudinal, centrally located and depended keel, comprising housings at front and rear portions of the ship opening downwardly therethrough immediately over the keel, the said keel having openings below said housings, caisson members mounted in the housings and supported for rocking movement therein about transverse axes, propeller units mounted in the caisson members and having their blade devices depended into the openings in the keel, and automatically controlled means for rocking said caisson members about transverse axes for Varying the angle of thrust of the blade devices.

8. Apparatus for propelling and stabilizing a ship of the type having a hull and longitudinal, centrally located and depended keel, comprising housings at front and rear portions of the ship opening downwardly therethrough immediately over the keel, the said keel having openings below said housings, caisson members mounted in the housings and supported for rocking movement therein about transverse axes, propeller units mounted in the caisson members and having their blade devices depended into the openings in the keel, means for adjusting the blade devices about upright axes for steering the ship, and automatically controlled means for rocking said caisson members about transverse axes for varying the angle of thrust of the blade devices.

ADOLPH RONNING.

Images