US2363488A - Means for raising or lifting sunken or partially sunken vessels - Google Patents

Description

Nov. 28, 1944. R. F, BARTLETT 2,363,488

MEANS FOR RAISING OR LIFTING SUNKEN OR PARTIALLY SUNKEN VESSELS Filed March '26, 1942 s sheets-sheet 1 NOV 28, 1944- R. F.' BARTLETT 2,363,488

MEANS. FOR RAISING nOR LIFTING SNKEN OR PARTIALLY SUNKEN VESSELS Filed March 26, 1942 3 Sheets-Sheet 2 Nov. 28, 1944. R. F. BARTLETT 2,353,483

MEANS FR RAISING OR LIFTING SUNKEN 0R PARTIALLY SUNKEN VESSELS Filed March 2e, 1942 s sheets-sheet s Patented Nov. 28, 1944 MEANS FOR RAISING OR LIFTING SUNKEN OR, PARTIALLY SUNKEN VESSELS Reginald Frank Bartlett, Weybridge, England f Application March 2.6, 1942, 'serial No. 436,372 In Great Britain January 1, 1940 'ZClaims (Cl. 114-50) y This invention relates "to an improved method of and means for lifting submerged or partially submerged Vessels by means of compressed air or gases in such manner that the maximum use is made of the flotation power of the vessel itself without damage thereto. By such use of the .fiotationvpower a great simplification in the work and equipmentis effected together with a saving in the under-water labour required-and lifting operations hitherto considered impracticable are rendered possible.

It has previo-usly been proposed'to employ compressed air for this purpose in the case of capsized sunken vessels and compressed air has been applied to war vessels and the like that normally :1 15

assume this position when unstable. n

The object `of the invention is' to provide a method of and means for lifting by compressed air for use in the case of more lightly built craft which may sink in the normal or nearly normalfao position. Hitherto this has been vimpracticable owing to the deckv structure being too weak structurally to withstand the unbalancedpressure arising during the lifting operationunless very heavy stiiening is resorted to. *25

According to the present invention the method comprises forming a 'substantially air and water tight compartment or compartments in they submerged or partially submerged vessel which when empty or partially empty is of suicient size to '30 *provide the necessary flotation powerto raise the vessel, removing the water contained'in'such compartment or compartments by a pump or other mechanical means and at the same time admitting compressed air or gas to the spacevr ,a5

voided bythe water through one or more valves each of which is arranged to supply the air-'or gas automatically in such a mannerth'at throughoutv the operation the internal pressure balances theexternal hydrostatic 'pressure'on the weak- 40 est part of the compartment or balances it to suchan extent that the vresultant external or internal pressure is always maintained below the limit at which said weakest part of the com-y partment might be damaged bythe pressure, the compartment also being tted with a twoway safety valve or two separate valves arranged to maintain a balance of pressure betweenthe admitted air or gas and the water by releasing Aexcess of air pressure arising from any cause or likewise to enable flooding to take place rin the event of the internal pressure falling out of balance.

In carrying out the invention it is necessary suflicient proportion thereof, to provide sufficient voids in order that when the water is displaced by air, enough flotation power may bevebtained. When this is done a submersible pump, which may be electrically'driven, air motor driven, of the air displacement type, of the air lift,, or any convenientV type, is preferably, vbut not necessarily, placed in the hold or holds -with'its suction inlet located at the lowest point. The outlet therefrom-is taken` to the deck or hatch level or point at' which'itis determined 'that the structure will lbe weakest, and fixed there, itrbe'ing unnecessary and undesirable to carry the outlet to the surface. At this point, namely, where it passes through the hull or hatch or deck, a nonreturn valve' is fitted.`

It is desirable, but not necessary, to fix in the hold during the operations an indicator whereby the actual water level existing in the hold at any stage of ythe operations maybe recorded at they surface.

Next Aall openings lin the hold or holds are cov ered with a wooden or steel hatch cover or patch or mattress of well-'known form, and secured in the usual manner. It is unnecessary for this to be` of heavy construction, and the customary wooden hatchcoversl are quite suitable for the purpose provided that whatever method is used itl should be as watertight and? airtight as possible under the circumstances, and provided always that it is fixed in such manner that itwill withstand either upward or downward pressure. y At no time is itnecessary for this hatch cover to sustain aload in either direction of any magnitude and by experiment it has been found that a load of plus or minusv up to ,4 lbs. per square inch is desirable but this may be controlled within nner or coarser limits as may loer deemed advisable. It is' not necessary in every case to repair a damaged yhull below the surface before lifting, as suicient lifting power may be ob tained from adjacent holds.

At a suitable point in the deck or wherever may be determined as the structurally weakest point, oneA or more valves constructed according to the invention are fitted. vThe function of ythese valves is to admit compressedl air or rgas at a pressure corresponding to the hydrostatic pressure existing at the predetermined point referred to above. vIn addition a two-way safety valve, or two separate valves are provided and arranged to maintain a balance of pressure in the hold between the admitted air or gas and as a preliminary step to remove the cargo, or a the water by releasing excess of air pressure or number of automatically operating balance valvesv fitted must be suitably increased to permit of the release, in the allowable interval of time, of the expanding air as the vessel rises to the surface and under a gradually decreasing external v pressure.

Where vessels are designed to sustain pressure in all directions such as a submarine, the method may be used with advantage. In this case the various valves may be tted by the use of trepanning tools without loss of contained air or admission of further water. I'he valves would be adjusted to an out of balance pressure sufficient to eject all water and internal water ejected through the non-return valve by air pressure only. The automatic valves will preserve vthe structure of the vessel at all and any trim that the vessel may assume in the course of the operations.

For a like reason with the normal type of vessel, this method eliminates the danger of loose internal water uncontrolled by bafes, swashplates or other means for controlling surging when lifting as no matter what trim the vessel may assume the operation of lifting is not interfered with and trim can be adjusted at the surface.

The invention can conveniently use compressed air, compressed air and steam mixture, or Very advantageously a mixture of steam and combustion gases as produced under pressure in theinternal combustion boiler, or any other gas or mixture of gases under pressure.

To enable the invention to be fully understood it will now be described by reference to the accompanying drawings, in which:

Figs. -1-4 inclusive are sectional elevations showing diagrammatically sunken vessels having various forms of the invention applied thereto, the section in each case representing a selected hold or compartment in the vessel,

Fig. 5 shows the application to a sunken vessel of a modied form of the invention,

Fig. 6 is a sectional elevation of one of the automatic valves constructed according to the invention, and

Fig. 7 is a similar view of another type of valve used.

Referring/to Fig. 1. A salvage vessel I isshown on the surface of the water above the submerged hull 2. The hatch opening of the selected hold or compartment of the hull is patched and made water and air tight by a suitable cover 8 so that the compartment is sealed and a sub mersible electric motor 3 is suitably suspended therefrom by a sling 5 and is in driving connection with a pump 4 having a flexible discharge pipe 6 connected to a non-return valve 1 in the hatch cover 8. The motor is supplied with power through the cable 9 from the salvage vessel, the cable passing through a Igland in the hatch cover as shown. A compressed air high pressure main I0 is laid along the deck of the hull 2 and is connected by a slip coupling II to the main compressed air supply pipe I3 carried by the salvage vessel and which is supplied with air from the Vessels compressors in the usual manner. A branch pipe Illa from the main IU opens into the hold and an automatic high pressure air inlet and reducing valve I2 is fitted thereto as shown. This valve is shown in section in Fig. 6 and is automatically controlled by the hydrostatic pressure. A two-way balance valve I4 is also fitted to the hatch cover 8 and connected to a flexible dip pipe I5 the lower end of which is below the surface of the Water in the hold. This Valve is shown in Fig. 7 and operates to release excess of air pressure or to enable flooding to take place through the pipe I5 in the event of the internal pressure falling out of balance. .This valve is also automatically controlled by the hydrostatic pressure at its point of iixture similarly to the valve I2.

'I'he lvalve I2 is set at the weakest point of the deck structure of the vessel and, inV conjunction with valve I4, automatically maintains the internal pressure at the equivalent external hydrostatic pressure at the point of fixture and thus balances the pressure taking the strain off lthe structure. Thus if the receiver pressure is P3 and the hydrostatic pressure at the valve I2 is P1 then the pressure on both sides of the deck and within the hold will be P1. It will also be seen that if thepressure at the bottom of the vessel externally is P2 and if the internal water is pumped out the stress on the hull at that point will be PZ-Pl, but this resultant pressure will not exceed that for which this part of the structure was normally designed.

Fig. 2 shows a similar case but in this example the submersible electric motor is replaced by an air or gas motor I6 coupled to the high pressure supply by the pipe I8 through the hatch cover t and exhausting through I'I into the hold at a back pressure equal to P1 i. e. the external pressure on the hatch or deck.

Fig. 3 shows a further case wherein an air or gas displacement pump I9 is used in place of a mechanically driven pump. 2li indicates the inlet water valves and 29a the reservsing air pressure valve and I'I the exhaust pipe of the pump. In this case as in Fig. 2 the pump exhausts under a back pressure equal to P1: High pressure air or gas is supplied to the pump through the hatch cover 8 by means of pipe I8 in both cases but the back pressure of the pumps reduces the amount to be supplied from the salvage vessel direct.

Fig. 4 shows a further case wherein an air or gas lift pump is used. In this case the mechanical pump is replaced by a high pressure air or gas lift pipe IBa having a perforated end Ilia inserted concentrically within the discharge pipe 20h. This discharge pipe may preferably be continued by the iiexiblepipe 22 held at the surface by the float 23 and by which the submergence effect is enhanced. Instead of the pipe 22 a nonreturn valve may be iitted in the pipe 20h at the hatch cover as in the other examples illustrated.

Fig. 5 shows the application of a modied form of the invention in the case of a vessel with damaged compartments wherein the structure of the vessel permits of a plus internal pressure either for the purpose of holding back water from leakage holes low down in the structure or of ejecting internal water by raising the internal pressure to P2. In this case a mechanical pump is not used, the water being expelled by air pressure in the usual way. The chief function of the invention is to control the pressure by automatic means at all stages of the salvage work yisolating valves 24fand to these valves the air re`- 1 ducing valve I2 and the balance and non-return valves I4 and 1 respectively are fitted as hereinbefore referred to in the Aother examples. The

,fair reducing valveI2 is setwith an out of balance internal load of P2-Pl'lbs. per square inch. In the eventl of a damaged hull the valve 1 would not be fitted but the out of balance load would be set to correspond to the depth of the fracture. By these means and by theuse of valves I2 and I4 violent surges of excessair through thel frac- "f square inch over that pertaining without. In a like manner by changing spring 43 the reverse effect may be obtained, and similarly by adjusting the' relative strength of springs 40 and 43 and arranged for automatic control by the external hydrostatic pressure. The valve comprises a body 26 having a high pressure inlet at 26a and a reduced pressure outlet'26b. The valve 21 itself is of the balanced type and is mounted on a stem 28. The stem carries a diaphragm mounted in a chamber 30a a pressure plate 34 being attached to the upper end of the stem and adjustably held bythe nuts or the adjustable stud 35a as shown. The pressure plate serves asan abutment for a loading spring 33 mounted in a chamber 33a attached to the diaphragm chamber the other` end ofthe spring bearing against shoulders 31 as shown. The external water is admitted to the uppersurface of the diaphragm through the ports 3I-for automatic working.

As shown, the spring 33 is arranged to place an upward out of balance pressure on the diaphragm 3E to any desired limit and can readily be adjusted. The out of'balance load acts upwardly and since the underside of the diaphragm is in communication through the `ports 29 with the low pressure side which communicates with the vessels hold it follows that the resultant pressure in the hold equals the surrounding pressure P1 p-lus that given by the spring.

The spring is conical and by reversing it so that the narrow end of the frustum vbears on a second pressure plate 32 attached to the stem 28 adja-l cent to the diaphragm while the other end bears on the plate 34 together with removal of nuts 35 and adjustment of stud 35a the action is reversed and the resultant pressure within the hold will equal Pl minus the spring pressure.

Fig. 7 shows diagrammatically one form of two way balance or-"overpressure valve fitted into a hatch cover. rThis valve may be constructed in are light springs then the internal and externalpressures are maintained balanced within a few ounces. If on the other hand spring is replaced by one to give a load on the valve equivalent to X lbs. per square inch, then the internal pressure will be maintained at P1 plus X lbs. per

any desired degree of sensitiveness or out of balance load may be obtained.

`In the operation ofthe invention as water is pumped out of thehold 2 by any of the Various means hereinbefore described high pressure air or gas is'fed through valve I2 until the predetermined internal pressure is reached. It will be realis'ed that in the case'where the back pressure of air orgas drivenpumps is utilised very little air`0r gas will be supplied through valve I2 and any excess will be released by valve I4. Both valves I2 and .I 4 may be set to any desired out of balance load, plus or minus, by changing or adjusting the. appropriate springs, alternatively' they may be set to equalise the pressure within a few ounces of absolute balance.

At the point of neutral and positive buoyancy Valve I2 ceases to function and valve I4 blows olf the excess air pressure and volume as the vessel rises. One or more of these valves are fitted depending upon the depth and the volume of air to be released in av given. time interval.

Should the salvage work be left in an uncompleted stage by stress of weather or other cause,

no harm can arise to the sunken vessel as valve I2 prevents loss of air by breakage of the pipe line I3 and should air leak from other points valve I4 adjusts the loss by flooding through the valve -and pipe I5.

-of the salvage equipment will be within the hold of the vessel and receive the maximum protection therefrom against sea action.

While itis preferable in mo'st cases to mount the pumping gear within the hold of the submerged vessel it is not essential as such gear may be carried on the deck of the sunken vessel if desired.

I claim:

1. A method of lifting a submerged vessel which comprises forming a substantially air and water-tight compartment therein, removing the water contained in such compartment by pumping, admitting compressed gas to the space voided by the water controlling the supply of gas automatically in such a manner that throughout the operation the internal pressure balances the eX- tially submerged vessel having at least one comternal hydrostatic pressure on the weakest part of the compartment, maintaining a balance of pressure between the admitted gas and the water by releasing excess of air pressure arising from any cause, and flooding in the event of the internal pressure falling out of balance.

2. The method of claim 1 characterized by the fact that the removal of the water is accomplished by suction.

3. Apparatus for lifting a submerged or parpartment adapted to be made Water and airtight, comprising in combination means for removing water from said compartment, means for admitting a gaseous medium under pressure to the space voided by the Water and means for automatically maintaining a balance between the internal pressure and external hydrostatic pressureon the weakest part of said compartment such that the resultant external or internal pressure is always maintained below the limit at which said weakest part of the compartment may be damaged by the pressure, said means comprising atleast one valve adapted automatically to control the admission of said gaseous medium and valve means fitted to said compartment adapted to release excess of internal pressure in said compartment arising from any cause or to enable flooding to take place in the event of the internal pressure falling out of balance.

4. Apparatus as defined in claim 3 in which said valve for controlling the admission of said gaseous medium to the space voided by the Water is a reduction valve automatically controlled by the external hydrostatic pressure, said valve adapted to be set to predetermined out of balance limits in relation to the external hydrostatic pressure.

5. Apparatus as defined in claim 3 in which said valve means tted to said compartment `comprises a two-Way balance valve fitted to the weakest part of the top of said compartment and connected to a dip pipe the lower end of which is below the surface of the Water in said compartment.

6. Apparatus for lifting a submerged or partially submerged Vessel having at least one compartment adapted to be madewater or airtight, comprising'in combination means for removing l water from said compartment and at the same and means for automatically maintaining a balance between the internal pressure and external hydrostatic pressure on the weakest part of said compartment such that the resultant external or internal pressure is always maintained below the limit at which said weakest part of the. compartment may be damaged by the pressure, said means comprising at least one valve adapted automatically to control the admission of said gaseous medium and valve means fitted to said compartment adapted to release excess of internal pressure in said compartment arising from any cause or to enable flooding to take place in the event of the internal pressure falling out of balance.

7. Apparatus for lifting a submerged or partially'submerged vessel having at least one compartment adapted to be made Water or airtight, comprising in combination means for removing Water `fromisaid compartment and at the same time admitting a gaseous medium under pressure to the space voided by the Water consisting .of a gas lift pipe fitted internally in the compartment to be evacuated and'adapted to discharge externally from said compartment and means for supplying a gaseous medium thereto under pressure, and means for automatically maintaining a balance between the internal pressure andexternal hydrostatic pressure on the weakest part of said compartment such that the resultant external or internal pressure is always time admitting a gaseous medium under pressure to the space voided by the water consisting of a submersible pump displacing a gaseous ;me dium fed thereto under pressure, the said pump operating under back pressure conditions and exhausting into the voids created by pumping,

maintained below the limit at which said weakest part of the compartment may be damaged by the pressure, said means comprising at least one valve adapted automatically to control the admission of said gaseous medium and valve means fitted to said compartment adapted to release excess of internal pressure in said compartment arising from any cause or to enable flooding to take place in the event of the internal pressure 4falling out of balance.

REGINALD FRANK BARTLETT.

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