US3109185A - Apparatus and method for launching and recovering lifeboats in rough seas - Google Patents

Description

Nov. 5, 1963 M. o. MILLER 3,109,185

- APPARATUS AND METHOD FOR LAUNCHING AND RECOVERING LIFEBOATS IN ROUGH SEAS Filed April 18, 1962 2 Sheets-Sheet 1 INVENTOR. MARVIN 0. MILLER BY 62...) Mae ATTdRA/Eg 3 5 Nov. 5, 1963 M. o. MILLER 3,109,185

APPARATUS AND METHOD FOR LAUNCHING AND RECOVERING LIFEBOATS IN ROUGH SEAS Filed April 18, 1962 2 Sheets-Sheet 2 FIG. 6

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2/ MARI/IN OAMILLER 22 BY I 23 2 ATTOR/VZE United States Patent APPARATUS AND METHOD FOR LAUNCHING AND RECOVERING LH EBOATS 1N RQUGH SEAS Marvin 0. Miller, El Cerrito, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Apr. 18, 1962, Ser. No. 188,590 6 Claims. (Cl. 9-34) (Granted under Title 35, US. Code (1952), sec. 266) 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 apparatus and more particularly to techniques for launching and recovering life boats in rough seas.

The primary purpose of a boat handling "system is to safely launch and recover lifeboats at sea. When the sea is dead calm this can be accomplished with little difficulty. However, as the sea builds up, relative motion between the boat and ship makes handling dangerous. Wave action buffets the 'small boat. Lifting gear sweeps back and forth. Crew members are hard put to keep their equilibnum.

Dtuing launching, the period between the time the boat first touches the crest of a wave and moment the boat is released from the hoist is very hazardous. Likewise, the matching period of the reverse process during recovery, is even more critical since the hoisting operation requires a high positive power input as compared to a braking power release during launching.

Standard launching equipment includes a strongback mounted on davitheads which in turn roll on trackways supported by the ships deck. A pair of falls blocks are strung on the strongback and adapted to be hooked to the forward and aft lifting pads of a boat. The operating and braking power :are furnished by a boatwinch mounted on the ships deck. In operation, when the boat is lightly waterborne an attempt to release or fasten both hooks simultaneously frequently results in only one of the two hooks making connection whereby the boat pivots about that point multiplying the problems of making the second hook-up. During this procedure, the probability of being'hit by one of the heavy swinging blocks is dangerous. Even after both hookups are made, during slow lifting, under direct power from the boat-winch, wave action jars the boat causing alternate slack and strain in the hoisting gear and impact loads on the boat crew.

The general object of this invention is to overcome the aforesaid disadvantages and provide a fast safe method and apparatus for recovering a lifeboat in rough waters.

The proposed boat handling system fulfills the fol-lowing outstanding objectives: (a) Rapid positive means for hook ing and unhooking the lifting gear; (b) ability to free the boat as soon as it hits the water on launching; (0) means for rapidly hoisting the boat clear of sea action as soon as the lifting gear is attached on recovery; (d) means for avoiding impact loads; (e) capability for darkened ship night operations; (f) maximum safety and dependability throughout the entire operation. 7

An object of this invention is to provide a single point lift hoist employing a quick attachment and release hook in combination with a rigid boat sling adapted for said single point lift.

Another object is to provide a special hoist hook and boat sling capable of quick connection or release by one man.

Still another object is to provide a modified strongback assembly by converting a two-point lift to a singlepoint center lift and employing the original two-point blocks as counterweights, and a headache ball on the singlepoint center falls blocks to balance said counterweights.

Another object is to provide means for attachment between the headache ball and the quick release hook to facilitate one man handling of the hook.

A further object is to provide improvement to the conconventional double drum power boatwinch employed for raising and lowering the single falls block at normal operating speeds, by introducing means for greatly increasing said normal operating speeds upon demand by the operator.

Still another object is to incorporate into the hoisting system a hydraulic transmission comprising an accumu later and ram with separating multiple sheaves for rapid independent takeup of the hoisting :cable and quickly raising the boat above the water during recovery.

Another object is to provide a novel boat sling and a quick connect-disconnect hook adapted to be attached to the sling at any point along its entire length and be free to slide along and center itself longitudinally on the sling regardless of the point of first attachment so that the boat will automatically trim as soon as the hoisting cable is taut.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by referernce to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view illustrating an apparatus for quickrecovery of lifeboats in rough seas;

FIG. 2 illustrates an overhead View of a lifeboat equipped with a novel rigid lifting sling designed for quick connect-disconnect hoisting operation;

FIG. 3 is a schematic drawing of the quick connectdisconnect hook employed on the hoist;

FIG. 4 illustrates the quick connect-disconnect hook attached to the boat sling;

FIG. 5 is a schematic illustration of the hydraulic transmission employed in the invention; and

FIG. 6 is a schematic drawing showing a standard strongback and rigging as modified for the proposed hoist.

In detail, the complete invention is shown in FIG. 1 wherein a boat hoist comprising a modified strongb-ack 10 mounted on davit heads 11 are carried by ship 12. The rigging is powered by a double drum boatwinch 13 to which a cable 14- is attached and is guided through the various sheaves to the center fall block 21 attached to the quick connect-disconnect hook 24. Cable 14 runs from the boatwinch 13 over the multiple sheaves 16 and 17 on opposite ends of the hydraulic ram 15 and through the original falls blocks 19 and 2t} serving in the modified form of rigging (FIG. 6) as counterweights, and terminating in the center block 21. The quick connect-disconnect hook 24 is attached to the block 21 by means of the pendant 23 and headache ball 22.

flhe hook 24- (FIG. 3) is of a special design for rapid coupling to or uncoupling from the special lifeboat sling 28-. As illustrated in FIG. 2, arigid pipe sling 28 in the shape of an inverted V is fastened to fore and aft pads in the lifeboat 27 in line with the keel or center line of the boat. The sling 28 is supported in an upright position along the boat center line by stays 29 attached to the boat gunnels. The original model sling 28 was constructed .any point along its entire length; As tension is exerted by the hoisting cable the hook will slide up the sling 28 to the vertex at which point the hoisting tension is exerted. Spring latches 36 at the top of the sling 28 are provided to restrain the book 24 after it slides up the sling to the highest point. This structure is shown in detail in FIG. 4.

The hook '24 is preferably connected to cable 14 through pendant 23, headache ball 22 and center falls block 21, FIG. 6-. In operation the hook 24 is manually held by handle 31 with its open jaw directed toward the sling 28. By pulling lanyard 26, plunger 34 is released and latch '33 is opened. When in a suitable position, the hook is forced over the sling 28 which will automatically close the jaws when the lip 35 is pressed by the sling 2S and thereafter will be secured by locking plunger 34. When this operation is completed someone on deck will operate the hoist for cable take-up thus further assuring closure of the jaws as the hook 24 rides up the sling sides to the vertex of the V where the spring keeper 35, FIG. 4, prevents the hook from sliding back in case of slack in the cable resulting from wave action.

To prevent slack in the cable, the general purpose of the apparatus is to provide means for rapid recovery of the boat the instant the hook 24 is attached to the sling 28. An operator on deck would normally after signal or on sight, open quick acting large opening throttle valve 38, FIG. 5, thus, discharging the hydraulic accumulator 18 into the ram 15 which in turn causes the multiple sheaves l6 and 17 on opposite ends of the expanding ram 15 to separate at high speed, thus, taking-up considerable cable 14 resulting in raising the hook 24 and boat 27 clear of the ocean surface and providing a rapid recovery.

In practice, the ram 15 was provided with four part sheaves having a maximum travel of eighty inches. Therefore, the total cable take-up was 26 feet and 8 inches. The ram cylinder bore used on test was 6 inches in diameter and the piston rod diameter 4 inches. The acoumulator had a capacity of 324 cubic inches and a nominal Working pressure of 3000 psi. By applying the hoist to a 26 foot mot-or whale boat, a state of equilibrium between load and ram thrust occurred at a point when the internal pressure dropped to about 1700' p.s.i. At this point the boat had been lifted 25 feet in a period of seven seconds. Increased loads would reduce the total lift but the recovery period would still be less than normal thereby providing a rapid recovery from the ocean surface up to the point of equilibrium between the diminishing ram power and the boat load. In any case, this would be an improvement in recovery time over the ordinary boatwinch lift.

Upon completion of the ram stroke, the boat may be clear of the water but not hoisted to its complete recovery position. In the structure illustrated, any stop of the block 21 against strongback 10* would dead end or limit the recovery. When this point in the operation is reached, the operator must continue to operate the boatwinch 13 which will compress the ram 15 and discharge the hydraulic fluid therefrom through the check valve 37 into the accumulator 18, thus, charging the accumulator and cocking the ram ready for the next rapid recovery.

The main advantage of the apparatus described is gained in recovery of boats from rough seas. However, the combination provides an advantage for 'launehings also. When a boat is lowered into the water by paying line ed the double drum winch through the closed lifting ram, as soon as the boat is afloat, one man could trip the single point quick connect-disconnect hook from the rigid boat sling, thus, freeing the boat from the hoist and avoid the many disadvantages of a two point lift. Immediately thereafter the falls blocks 19 and 20, acting as countenweights, would operate to take up the slack and raise the hook clear of the boat and its personnel.

Although the proposed system may employ a single davit structure, it is also adapted to the standardstrongback structure now used on ships, with some modification. In FIG. 6 the'strongback lilis rigged with a single cable supporting the main lifting lock 21 provided with a headache ball 22, pendant 23 and quick connect-disconect book 24. The original double falls blocks 19 and 20 are sheaved by the cable 14 but employed as counterweights in the modified rigging.

Various components may be substituted for those shown as preferred but the general principle and the system for accomplishing the purpose will be within the improved method for launching or recovering of lifeboats from rough seas. i

What is claimed is:

l. A hoisting apparatus for rapid recovery of lifeboats in rough seas comprising a davit structure mounted on a ship, cable actuated lifting gear supported by said davit structure and powered by a boatwinch on said ship, said boatwinch being adapted to hoist said lifeboat by said cable gear at a normally slow rate of speed, and. an accumulator actuated hydraulic transmission adapted to hoist said lifeboat independently of said boatwinch by said cable gear at a rapid rate of speed, said hydraulic transmission being powered by said boatwinch cable gear tension after full recovery of the lifeboat by said boat- I winch.

2. A hoisting apparatus for rapid recovery of lifeboats in rough seas comprising a power boatwinch in combination with an independently controlled hydraulic power transmission coupled to a single hoisting cable, said boatwinch acting through said hoisting cable providing the sole power source for said hoisting apparatus, a davit structure mounted on a ship, a running rigging supported by said davit structure and including said single hoisting cable extending from an attaching hook for hoisting boats to said boatwinch power source on said ship, and said hydraulic power transmission being independently controlled and accumulator operated and being connected to said cable in a manner to complement the power boatwinch and provide faster take up of the cable so that normal and rapid recovery of the attaching hook for hoisting boats is provided independently, said accumulator being charged by the boatwinch take-up cable tension after the hook has reached its stop.

3. A device as described in claim 2 whereinsaid hydraulic power transmission comprises an accumulator connected through a quick acting large opening'throttle .valve to a hydraulic ram, multiple sheaves mounted on opposite ends of the ram and having said hoisting cable reeved through said sheaves, the power discharge rate of said transmission accumulator driving the ram greatly exceeding the hoisting power rate of said boatwinch so that the ram expansion will multiply the hoisting cable take-up speed and provide rapid boat recovery.

4. A device as described in claim 3 wherein the ram is retracted to a cocked position and the accumulator pressure raised to a maximum through a check valve connection to the ram concurrently with and as a result of the full recovery of the cable by the boatwinch operation of taking up cable, and extension of said cocked ram for power operation is controlled by said quick acting large opening throttle valve to direct high pressure hydraulic fluid from the accumulator to the ram.

5. A hoisting apparatus for rapid recovery of lifeboats in rough seas comprising a davit structure mounted on a ship, a. running rigging supported by said davit structure, a boatwinch on said ship for powering said rigging, a single lifting falls block operably supported by said rigging, a quick connect hook attached to said block, a boat equipped with a sling in the shape of an inverted V and provided with a center lifting point at the vertex of the V, said sling being a rigid, one piece structure so that the said quick acting hook canbe attached at any point along the sling and freely slide to said vertex when the said rigging is placed under tension, and a high speed hydraulic transmission operably connected to said rigging between the boatwinch and hook, said hydraulic transmission including a hydraulic ram having multiple sheaves mounted on opposite ends of said ram and having said rigging reeved through said sheaves, an accumulator connected by a quick-acfing large-opening throttle valve to said ram, 21 power relationship between the transmission and boatwinch being provided so that the peak power output rate of said ram and accumulator during hoisting greatly exceeds the uniform rigging take-up rate of the boatwinch, said power relationship further being such that continued operation of said boatw-inch subsequent to accumulator discharge acts through said rigging to recharge said accumulator, whereby continued operation of the boatwinch continues the hoisting initiated by said ram accumulator and subsequently recharges the accumulater.

6. A hoisting apparatus for rapid recovery of lifeboats in rough seas comprising a lifeboat equipped with a sling comprising a single point lift, :a cable power hoist mounted on a ship and adapted to take-up and pay out hoisting cable, a quick connect-disconnect hook fastened to said cable and adapted to be readily attached to said sling at any point and hydraulic power means comprising an accumulator connected to a hydraulic ram having multiple sheaves mounted on opposite ends of said ram and said hoisting cable reeved through said sheaves, a passage containing a check valve connecting the ram to the accumulator so that the accumulator will be automatically charged as the ram is compressed, a second passage containing a quick acting large opening throttle valve connecting the accumulator to the nam for high speed expansion of the ram so that the hoisting cable will be taken up more rapidly by said hydraulic means than by the power hoist acting directly upon the hoisting cable, said sling being a rigid structure in the shape of an inverted V disposed longitudinally of the boat with one leg fastened in the bow and the other in the stern and the vertex placed at the highest point of the sling and forming the single point lift, and said hook being designed to snap onto said sling at any point of the slings length and said sling being a single piece, rigid structure so that said book will be automatically raised to said highest point when tension is exerted on said cable and a spring latch at the top of the sling for restraining the hook at its highest point if cable tension is released.

References Cited in the file of this patent UNITED STATES PATENTS Crenshaw Aug. 9, 1960

Claims (1)

1. A HOISTING APPARATUS FOR RAPID RECOVERY OF LIFEBOATS IN ROUGH SEAS COMPRISING A DAVIT STRUCTURE MOUNTED ON A SHIP, CABLE ACTUATED LIFTING GEAR SUPPORTED BY SAID DAVIT STRUCTURE AND POWERED BY A BOATWINCH ON SAID SHIP, SAID BOATWINCH BEING ADAPTED TO HOIST SAID LIFEBOAT BY SAID CABLE GEAR AT A NORMALLY SLOW RATE OF SPEED, AND AN ACCUMULATOR ACTUATED HYDRAULIC TRANSMISSION ADAPTED TO HOIST SAID LIFEBOAT INDEPENDENTLY OF SAID BOATWINCH BY SAID CABLE GEAR AT A RAPID RATE OF SPEED, SAID HYDRAULIC TRANSMISSION BEING POWERED BY SAID BOATWINCH CABLE GEAR TENSION AFTER FULL RECOVERY OF THE LIFEBOAT BY SAID BOATWINCH.

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