US2891262A

US2891262A - Boat lowering device

Info

Publication number: US2891262A
Application number: US482910A
Authority: US
Inventors: Albert A Miller
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-06-27
Filing date: 1955-01-19
Publication date: 1959-06-23
Anticipated expiration: 1976-06-23

Description

June 23, 1959 A. A. MILLER 2,891,262

BOAT LOWERING DEVICE Original Filed June 27, 1951 3 Sheets-Sheet 1 INVENTOR. flif/P? A M41157? June 23, 1959 A. A. MILLER BOAT LOWERING DEVICE 3 Sheets-Sheet 2 Original Filed June 27, 1951 INVENTOR. 415M; A Mum? June 23, 1959 A. A. MILLER 2,891,262 BOAT LOWERING DEVICE Original Filed June 27, 1951 3 SheetsSheet 3 INVENTOR. 4455/??- 4 M1451? BOAT LOWERING DEVICE Albert A. Miller, Newton Highlands, Mass.

Original application June 27, 1951, Serial No. 233,926,

now Patent No. 2,698,949, dated January 11, 1955. Divided and this application January 19, 1955, Serial No. 482,910

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates in general to boat handling and more particularly to devices for lowering lifeboats, surfboats and similar craft. One difliculty encountered when a lifeboat or surfboat is lowered from the deck of a larger vessel or a pier arises at the time that the lifeboat reaches the surface of the water. If waves of a substantial size are present, the crest of a wave will momentarily support the lifeboat and cause the lowering cables to become slack. As the crest of the wave passes and the boat begins to fall into the following trough of the wave, the slack in the lowering cables is suddenly taken up due to the removal of the support of the water. The shock of the sudden tightening of the lowering cables is often sufficient to tear loose the pads to which the lowering cables are attached. In other instances other damage to the boat may result from the alternate rising and falling of the boat when attached to the lowering cables. It would be desirable in such instances to suddenly increase the speed of lowering of the boat at the instant that the boat is first supported by the crest of the wave so that when the following trough of the wave occurs the boat is still supported by the water and the lowering cables remain slack. However, it is impractical to design lowering Winches or braking devices capable of providing this rapid acceleration of the lowering speed. This application is a division of copending application Serial Number 233,926, filed June 27, 1951, now Patent No. 2,698,949, for Boat Lowering Device by Albert A. Miller.

The present invention comprises an auxiliary arm secured to the lowering davit and extending into engagement with the lowering cables so as to form a bight therein, a latch, preferably under the control of the lowering operator, permits the arm to move into a position which effectively removes the bight thus increasing the effective length of the lowering cable.

From the above description it can be seen that it is an. object of the present invention to provide an improved device for lowering small boats from the deck of a larger vessel'or from a pier.

Another object of the present invention is to provide means for rapidly increasing the lowering speed of a small boat.

Still another object of the present invention is to provide novel means for introducing slack into a lower ing cable.

.Other objects, features and advantages of this invention will become apparent from the following description of the invention which should be read in conjunction with the accompanying drawings in which:

. Fig. 1 is a pictorial drawing of aboat lowering device embodying the present invention;

United States Patent O Fig. 2 is a detailed view of a portion of the lowering device of Fig. 1; r

Fig. 2A is an enlarged view, partially broken away, of the latch mechanism of Fig. 2;

Fig. 2B is a cross section of the structure of Fig. 2 taken along the line B--B;

Fig. 3 is a detailed view of a second embodiment of the present invention which may be employed with the lowering device of Fig. 1;

Fig. 4 is a frontal view of still another embodiment of the present invention; and

Fig. 5 is a plan view of the embodiment of the invention illustrated in Fig. 4. 6

Referring now to Fig. 1, 10 represents the supporting vessel on which the smaller boats 12 are normally transported. Only a fragmentary view of vessel 10 is included since the operation of the present invention is .not materially affected by the design of vessel 10. The lowering device illustrated in Fig. 1 is generally similar to the Welin Triple Bank Gravity Davit manufactured by the Welin Davit and Boat Corporation, Perth Amboy, New Jersey. While this boat lowering device has been selected for the purpose of illustrating the present invention, it should be understood that the present invention is not limited in its application to such davits but may be equally applied to crescent type gravity davits and other well-known types of controlled lowering davits.

The davits illustrated in Fig. l comprise trackways l4 and 16 which are secured at their lower ends to the deck 18 of vessel 10 by brackets 20 and 22, respectively. The upper ends of trackways 14 and 16 are supported in an elevated position by brackets 24 and 26 also secured todeck 18. Two

davit heads

28 and 30 are movable from an inboard to an outboard position along trackways 14 and 16, respectively. A strongback 32 is provided between

davit heads

28 and 30 to support lowering cables which are attached to boat 12 by means of floating blocks 34 and 36. Floating blocks 34 and 36 may be secured to suitable pads on boat 12 through the use of quick-

release hooks

37 and 39, respectively. Hooks 37 and 39 may be of the type known to the marine art as the Raymond hook. The cabling for the particular davit illustrated is as follows. One end of the hoisting cable 38 is anchored to the deck 18 through shock absorber 40. Cable 38 then passes over a sheave 42 at the upper end of trackway 14 and enters strongback 32 over a second sheave (not shown). Cable 38 then passes over suitable sheaves in strongback 32 and thence to the floating block 34 asillustrated at 38a. Cable 38 then passes back to strongback 32 as shown at 3812. After passing over appropriate sheaves in strongback 32, cable 38 emerges therefrom as shown at 380. A suitable sheave 46 is provided to change the direction of cable 38 to a direction parallel to the arm of the davit head 28. In the conventional Welin davit of the type herein used for illustrative purposes, the cable 38 passes substantially in a straight line from sheave 46 to a second sheave 48 also located on the davit head 28. From sheave 48 cable 38 passes over a second sheave 52 located at the upper endof trackway 14, thence through a deck sheave 54 to a hoisting winch. Davit head 30 and floating block 36 are controlled by a second lowering cable 56 which passes over a series of sheaves substantially identical to the sheaves above described. The free end of cable 56 preferably passes to the same winch that controls cable 38. .[This winch is generally provided with a separate drum for winding each cable and suitable braking mech.-, anisms to allowgravity lowering of the boat 12.

- In the present invention, the lowering cableat38c1 passes over an auxiliary sheave 62 thence around sheave 64 and a second auxiliary sheave 66 to sheave 48. Sheave '64 is mounted on a support arm 68 which is slidably journalled in a guide bracket 70 secured to the side of the davit head 28. A latch member 72 and a lanyard 74 secured thereto is provided for controlling axial movement of arm 68.

Reference should'now be made to Figs. 2, 2A and 2B which show in greater detail the construction of support arm 68 and guide bracket 70. Parts in Figs. 2, 2A and 2B have been given reference numerals corresponding to like parts in Fig. 1. Referring particularly to Fig. 2B, it will be noted that guide bracket 70 is fastened to davit head 28 by suitable fastening means, for example, bolts 76. A rectangular opening 78 is formed in guide bracket 70 to slidably receive arm 68 and to permit a'xial'movement of arm 68. Support arm 68 is provided with stop member 82 at one end thereof and a stop "plate 84 at the other end thereof for limiting the amount of axial travel of arm 68. A tension spring 85 is connected between stop plate 84 and guide bracket '70 to urge arm 68 toward the left as shown in Fig. 2.

Guide bracket 70 is formedwith a second opening inthe side thereof to receive the latch bolt 86 of latch '72. Latch bolt 86 is secured to davit head 28 by bolts 88 which pass through elongated openings 90 formed in latch bolt 86, the elongated openings 90 permitting limited amount of movement of latch bolt 86 in 'a direction perpendicular to the direction of movement of arm 68. A compression spring 92 which is fastened at one end to a post 94 mounted on davit head 28 normally urges latch bolt 86 into a notch 96 in arm 68. This notch is most clearly shown in Fig. 2A. Lanyard 74 is provided for withdrawing latch bolt 86 from notch 96 against the action of spring 92.

Fig. 2 also illustrates lowering cable 38 passing over sheave 64. A guard 98 is provided to prevent cable 38 from accidentally becoming disengaged with sheave 64 when the present invention is in operation. It is to be understood that a second device identical to that shown in Fig. 2 is provided on davit head 30.

The present invention operates as follows. Assuming that the winch is paying out cable 38 so that boat 12 is being lowered into the water, support arm 68 would normally be in the position shown in Fig. 2 with latch bolt 86 engaging notch 96 thus preventing axial movement of arm 68 within guide bracket 70. As will be seen from Fig. 1, the length of cable from sheave 62 around sheave 64 and back to sheave 66 is greater than the length of cable required to pass directly from sheave '62 to sheave 66. At the instant that boat 12 is first supported by the water or even when it is slightly above the water, lanyard 74 may be pulled disengaging latch bolt 86 from notch 96 and member 68. The tension in lowering cable 38 will then cause arm 68 to slide within guide bracket 70 until stops 82 engage guide bracket 70. This movement of arm 68 will introduce a considerable amount of slack in the lowering cable 38 which will be taken up by a rapid descent of floating block 34 under the weight of boat 12. The length of travel of arm 68 may be made great enough to introduce enough slack to compensate for the difference between the height of the wave from the crest to the trough. Thus, boat 12 may be dropped into the trough of a wave without danger of the lowering cables becoming taut and thus damaging boat 12 or the pads which engage hooks 37 and 39. With the boat 12 safely in the water, hooks 37 and 39 may then be released and the winch operated to raise floating blocks 34 and 36 into the position to lower another boat which may be located on deck 18. At any time before the next boat is lowered sufficient slack may be introduced in lowering cable 38 to allow arm 68 to return to its normal position with latch bolt 86 in engagement with notch 96. With arm 68 disposed in aposition illustrated'inFig. 1 the weight of arm 68 is usually sufficient to cause it to slide into its normal position as soon as tension in the bight *of cable 38 passing 'over sheave 64 is removed. However, spring is provided to positively urge arm 68 toward its normal position. It will be understood that in order to drop the boat into the water in a level position, the lanyard associated with the device mounted on davit head 30 should be pulled simultaneously 'with the pulling of the lanyard 74 thus introducing slack into lowering

cables

38 and 56 at the same instant. Alternatively, electrical, mechanical or hydraulic release mechanisms may beprovided for simultaneously tripping the two devices at the same instant.

Fig. 3 illustrates a second embodiment of the present invention in which an arm 102 is pivotally secured to davit head 28 by a bolt 104 passing through these two members. Bolt 104 maybe located on davit head 28 at a position between sheaves 62 and 66 and somewhat closer to sheave 66 than to sheave 62. Thus arm 102 will have a normal position very similar to that of arm 68 of Fig. 1. Arm 102 is provided with a sheave 106 and a cable guard 108 which serve the same functions as sheave 64 and cable guard 98 of Fig. '2. A latch bolt 118 secured to davit head 28 by fastening means 112 passing through elongated openings in latch bolt engages the notch 114 near the pivoted end of arm 102. A spring 116 corresponding to spring 92 of Fig. 2 is provided for normally forcing bolt 110 into engagement with notch 1.14. A lanyard 118 is provided for With drawing bolt 110 from notch 114. The embodiment of Fig. 3 operates in a manner quite similar to the embodiment illustrated in Figs. 1 and 2. 'When boat '12 has reached a position where it is supported or about to be supported by the crest of a wave lanyard 118 is pulled withdrawing bolt 110 from notch 114. The tension in lowering cable 38 will then cause arm 102 to rotate in a clockwise direction as shown in Fig. 3 until it lies in a position nearly parallel to a line drawn between sheave 62 and sheave 66. This movement of arm 102 will eliminate the bight in cable 38 and thus introduce sufiicient slack to allow boat 12 to drop into the trough of the wave. Arm 102 is prevented from rotating more than about a quarter turn by cable guard 108 which passes around lowering cable 38. Alternatively, a stop (not shown) may be added to davit head 28 to restrict the movement of arm 102. When the'boat 12 has been released and it is desired to restore arm .102 .to its normal position, this may be accomplished by introducing slack into lowering cable 38 and arm 102 will be returned to its normal position by gravity. A stop 122 is provided on arm 102 which will engage latch bolt 110 even though it is fully withdrawn from notch 114. Stop '122 will thus prevent arm 102 from rotating in a counter clockwise direction beyond its normal position. 'Again, mechanical or electrical devices may be provided for withdrawing bolt 11%) from notch 114, and means other than bolt 110 and notch 114 may be employed to control the rotation of arm 182 without departing from the present invention.

Figs. 4 and 5 illustrate still another embodiment of the present invention. As shown in these figures, an arm 132 is rigidly secured to davit head 28 at a point substantially midway between sheaves 62 and 66 of Fig. 1. Arm 132 extends generally in the plane defined by davit head 28 and trackway 14 and may be substantially perpendicular to the line between sheaves 46 and 48. A roller bracket 134 is pivotedat the outer end of arm 132 by means of a suitable pivot pin 136. Bracket 134 carries 'a roller 138 which in its normal position is substantially perpendicular to the plane of the bight in lowering cable 38. A latch bolt 142 engages a notch 144 on bracket 134 under the force of compression spring 146. Bolt 142 is mounted to arm 132 in a'manner'similar to that described above in connection with bolt 110. A lanyard 148 is attached to bolt 142 for withdrawing bolt 142 from notch 144. A cable guard 152 is secured 'to one side of 'arm 132by suitable brackets 154. To operate the device shown in Figs. 4 and 5, lanyard 148 is pulled which allows bracket 134 to rotate in a counter clockwise direction as shown in Fig. 5 due to the tension in lowering cable 38. As bracket 134 rotates in this counter clockwise direction, lowering cable 38 slips oft roller 138 and falls into cable guard 152 to the position illustrated in Figs. 4 and 5 by the dotted lines. Again this will introduce sufiicient slack into lowering cable 38 to allow boat 12 to rest in the trough of the wave without taking up all of the slack in the lowering cables. To aid in restoring bracket 134 to its normal position a tension spring 156 may be secured at one end to bracket 134 and at the other to arm 132 as at 158. Lowering cable 38 may be repositioned on roller 138 by introducing sufficient slack in this cable. Cable guard 152 will assist in the positioning of cable 38 on roller 138. As a further aid to positioning cable 38 on roller 138 a block 164 carrying a hook 166 may be slidably mounted on guard 152. Block 164 may be positioned by means of

lines

168 and 170 passing through guide openings formed in guard 152. Hook 166 has sulficient curvature to lift cable 38 onto roller 138 but is short enough to allow cable 38 to drop onto roller 138 as block 164 moves along the curved section of guard 152. In certain applications of the present invention block 164 may be dispensed with since cable 38 may be positioned on roller 138 by hand or by the use of other types of positioning devices adapted for this purposes. As in the previous embodiment of the invention a stop 162 has been provided to prevent bracket 134 from rotating in a clockwise direction past its normal position.

In general it will be preferable to employ the same embodiment of the present invention on each lowering cable of a pair but where other design factors conflict with such practice any combination of two of the three embodiments illustrated may be employed. It should be understood that the exact position of the present invention along the lowering cable is not critical and will depend to some extent on the design of davit with which it is employed. However, it is usually undesirable to introduce the slack at a position adjacent the winch for the reason that the winding drums of the winch are usually provided with spiral grooves for receiving the cable and the sudden introduction of a slack condition in the cable might interfere with the spooling of the cable in the proper groove.

While I have described What are presently believed to be the preferred embodiments of the present invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein Without departing from the spirit of the invention as defined by the hereinafter appended claims.

I claim:

1. In a boat lowering device, a davit head, a lowering cable passing adjacent said davit head, first and second sheaves mounted on said davit head in spaced relationship and in engagement with said cable, an arm means for rotatably securing said arm at one end to said davit head at a position between said first and second sheaves, said arm being movable from a first position substantially perpendicular to a line connecting said first and second sheaves to a second position substantially parallel to said line, a third sheave mounted on a second end of said arm and in engagement with said cable, said third sheave forming a bight in said cable when said arm is in said first position, a latch for releasably retaining said arm in said first position and means for actuating said latch.

2. In a boat lowering device including a davit head and a lowering cable passing adjacent said davit head, first and second sheaves mounted on said davit head and in engagement with said cable, an arm rigidly secured at one end to said davit head between first and second sheaves, a roller bracket rotatably secured to a second end of said arm, a roller carried by said roller bracket, and means for releasably securing said roller bracket against rotation, said cable when in contact with said first and second sheaves and said roller having a bight formed therein.

3. In a boat lowering device including a davit head and a lowering cable passing adjacent said davit head, first and second sheaves mounted on said davit head, an arm rigidly secured at one end to said davit head between said first and second sheaves, a roller bracket rotatably secured to a second end of said arm, a roller carried by said roller bracket, latch means for releasably securing said roller bracket in a first position, said cable normally passing around said first and second sheaves and said roller when said roller bracket is in said first position, said roller bracket upon actuation of said latch being rotatable to a second position at which the release of said cable from said roller is efiected, and a cable guard secured to said arm, said cable guard serving as a guide to reposition said cable on said roller upon the return of said roller bracket to said first position.

4. In a boat lowering device, a davit. head, first and second sheaves mounted on said davit head in spaced relationship, a lowering cable engaging said first and second sheaves whereby said lowering cable is adapted to extend along said davit head between said first and second sheaves in a straight line, first means, second means pivotally supporting said first means relative to said davit head between said first and second sheaves, rotatable means on said first means and adapted for engaging said lowering cable, latch means for engaging and restraining said first means in a first position and when released permitting said first means to pivot, whereby when said first means is latched in the first position and said rotatable means engages said lowering cable there is a bight in said cable between said first and second sheaves, and when said first means is subsequently unlatched said first means is pivoted by said cable to a position such that it permits said cable to extend in a shorter path between said first and second sheaves.

References Cited in the file of this patent UNITED STATES PATENTS 1,292,255 Cherry Jan. 21, 1919 2,073,566 Scheubner Mar. 9, 1937 2,698,949 Miller Jan. 11, 1955 FOREIGN PATENTS 27,718 Great Britain of 1913 501,324 Great Britain Feb. 24, 1939