US3448712A

US3448712A - Buoyant floats for docking and towing seacraft

Info

Publication number: US3448712A
Application number: US701586A
Authority: US
Inventors: Guenther W Lehmann; Alden W Adams Jr
Original assignee: General Dynamics Corp
Current assignee: General Dynamics Corp
Priority date: 1968-01-30
Filing date: 1968-01-30
Publication date: 1969-06-10
Anticipated expiration: 1986-06-10

Description

June 10, 1969 w, LEHMANN ET AL 3,448,712

BUOYANT FLQATS FOR DOCKING AND TOWING SEACRAFI.

' Filed Jan. 30, 1968 FIGQI.

FIGZ.

BUOYANT FLOATS FOR DOCKING AND TOWING SEACRAFT Filed Jan. 30, 1968 June 10, 1969 3, w H N ETAL Z of 5 Sheet June 10, 1969 r e. w. LEHMVANN: ET 3,443,712

BUOYANT FLoA'I's FOR DOCKING AND TOWING SEACRAFT I Filed Jan. 30, 1968 Sheet 3 of 5 June 10, 1969 w, LEHMANN ET AL 3,448,712

BUOYANT FLOATS FOR DOCKING AND TOWING SEACRAFT Sheet 4 ors Filed Jan. 30, 1968 June 10, 1969 G. w. LEHMANN ET AL 3,448,712

BUOYANT FLOATS FOR DOCKING AND TOWING SEACRAFT Filed Jan. 30, 1968 Sheet of 5 United States Patent 3,448,712 BUOYANT FLOATS FOR DOCKING AND TOWING SEACRAFT Guenther W. Lehmann, San Diego, and Alden W. Adams, Jr., Coronado, Calif., assignors to General Dynamics Corporation, New York, N.Y., a corporation of Delaware Filed Jan. 30, 1968, Ser. No. 701,586

Int. Cl. B63b 35/44, 35/00 US. Cl. 114-435 15 Claims ABSTRACT OF THE DISCLOSURE A float for docking and towing seacraft comprising a pair of elongated hollow bodies maintained in spaced relation by a fore strong cross beam and an aft strong cross beam, each secured at its outer ends to said hollow bodies in catamaran fashion to form a rigid unit; the unit being flipped to vertical position by introducing ballast water into the hollow bodies in which position the seacraft may engage the fore strong cross beam, after which the unit is swung upwardly about the fore strong beam as a fulcrum to horizontal floating position by removing ballast water with the underside of the seacraft resting on supporting members secured to the hollow bodies.

This invention relates to buoyant floats for docking and towing buoyant seacraft or like things in deep or shallow water and is especially adapted for docking and towing a seacraft in an area which may be subjected to high winds and heavy seas. The float may also be used for salvage operations.

Background of the invention and the prior art When seacraft such as a submarine is to be towed, particularly a research submarine, it has been the practice to tow it behind a small tender, or to transport such a submarine on the deck of a larger tender and then, by means of a shipboard crane, to lift the submarine from the deck and set it over the side of the tender into the sea at the site of operation. If small tenders are used, it is necessary to tow the submarine to the site of operation. Because of instable properties of small reesarch submarines, towing by small tender could proceed only at slow speed, perhaps not faster than four knots per hour. Hence, high speed transfer cannot be attained by towing the submarine with a small tender. When a large tender is used, and the submarine is set out from the deck by crane equipment, it has been the practice to transfer the craft from the deck of the tender to the sea with the crew on board. If a small tender is used, the crew has to board the research submarine while it is floating in the sea and since the submarine may be floating in an agitated sea, the crew may have to board her under most adverse conditions.

Summary of the invention In accordance with this invention, a docking and towing float is provided which can be used to tow the submarine to the site of ope-ration by fast speed tender, large or small, and the crew or operating personnel may board or leave the submarine floats at the surface of the sea. In order to provide favorable tow conditions and easy boarding or leaving the submarine by the crew or operating personnel, there is provided a float comprising two elongated hollow buoyancy bodies maintained apart in spaced substantially parallel relation by two main strong cross beams fore and aft of the pair of buoyancy bodies. One of these main 3,448,712 Patented June 10, 1969 ICC! cross beams is connected at its outer ends to the hollow bodies at the fore ends of the bodies and another main c-ross beam is connected at its outer ends to the hollow bodies at their aft ends, thus the pair of oppositely disposed bodies are connected in the fashion of a catamaran. A plurality of spaced elastomeric cross members positioned between the main cross beams are secured to the two buoyant bodies. The submarine may rest on these elastomeric c-ross members when the two hollow bodies are in a floating position on the surface of the sea in a manner that part of the submarine weight is supported by the buoyancy of the float and the remainder of the Weight is balanced by the buoyancy of the submarine itself. Means are providcd for introducing ballast into the hollow elongated bodies and for removing the ballast, which may, if desired, be the ambient seawater. By controlling the amount of ballast in the hollow bodies, they may be caused, as a unit, to assume a vertical position, in which case they are substantially submerged to facilitate the docking operation. Or. they may be caused as a unit, to assume a horizontal position, in which case they are floating on the surface of the sea with their long axes substantially horizontal, and with the submarine resting on the elastomeric cross members. The float provided by the invention is so contrived that it can be caused to move to a submerged, vertical position in the sea prior to docking the submarine on the float by introducing ballast into the hollow bodies. The submarine may then approach and contact the forward main cross beam. The submarine may then be docked on the float and with the underbelly of the submarine resting on the grid provided by the elastic cross members, by removing ballast in such sequence as to rotate the float about the fore strong main cross beam as a fulcrum, or pivot, so that the hollow bodies ultimately assume a horizontal position on the sea surface. In docking the submarine to the float, the submarine is smoothly contacted and partially lifted by the elastic cross members. When sufficient ballast water is removed, the float is floating in substantially horizontal position on the sea surface with the submarine resting on the elastic members. In this position the system (float and submarine docked thereto) is ready for towing as a unit. Also, platform or deck means may be provided on the float from which operating personnel may board the submarine without danger of flooding the submarine through a topside open hatch, even under adverse weather conditions. And means are provided for lashing the submarine to the float, if desired.

Although the features which are believed to be characteristic of the invention are pointed out in the annexed claims, the invention itself as to its obj cts and advantages and the manner in which it may be carried out may be better understood by reference to the following more detailed description, considered in connection with th accompanying drawings forming a part hereof, in which:

FIG. 1 is a view in perspective and partly diagrammatic illustrating the support and towing float in submerged vertical position with a submarine to be secured thereto floating on the surface of the sea and approaching the float;

FIG. 2 is a view in perspective and partly diagrammatic illustrating the submarine secured to the float and resting on the float and at standstill for boarding the submarine;

FIG. 3 is a side view in elevation and partly diagrammatic to illustrate the docking operation.

FIG. 4 is a side view in elevation and partly diagrammatic to illustrate the submarine and float in horizontal position after docking and ready for towing;

FIG. 5 is a plan view of FIG. 4;

FIG. 6 is a side view in sectional elevation, of one of the elongate hollow bodies, illustrating the float submerged in vertical position and containing ballast;

FIG. 7 is a side view in elevation similar to FIG. 6, having some ballast removed and showing the float in inclined position;

FIG. 8 is a side view in elevation similar to FIGS. 6 and 7, having more ballast removed and showing the float in horizontal position floating on the surface of the sea;

FIGS. 9 and 10 are views on lines 99 and 1010, respectively, of FIG. 8;

FIG. 11 is a side view in section of a modified form of float and in submerged vertical position; and

FIG. 12 is a diagrammatic and schematic perspective view illustrating the piping and electrical system for operation of the float.

Referring now to the drawings, in which like reference characters designate like parts throughout the several views, FIG. 1 illustrates a submarine 10 floating on the surface 11 of the sea; the submarine approaching the float (indicated generally by reference character 12) to be docked and made fast thereto, the full lines representing the parts which are exposed above the surface of the water. FIG. 2 represents the submarine after it is docked and made fast to the float 12; the float now lying substantially horizontally and floating on the surface of the water and the unit 23 (submarine and float) ready to be towed by a suitable towing craft, such as a power driven sea-craft or tender (not shown) by means of the towline 14, secured to the power craft and to the float 12 by

bridle

15, 15a.

The float comprises a pair of elongate

hollow bodies

16, 16a which are maintained in spaced parallel relation by means of strong

main cross beams

17 and 18, in the fashion of a catamaran. For convenience of description, the

hollow bodies

16, 16a are herein sometimes referred to as enclosed hulls. The fore strong beam 17 is securely connected at one of its outer ends 19 to body 16, and at its other outer end 19a to body 16a, a short distance from the bases of the generally cone shaped portions 20, 20a which, together with hollow bodies 25, a form the

twin bows

21, 21a of the float. The aft strong beam 18 is likewise connected at one end 22 to body 16 and at its other end 22a to body 16a near the stern end of the float. The

hollow bodies

16, 16a, herein referred to as hulls, are preferably of general cylindrical shape and are constructed for and aft as described in further detail hereinafter. The hulls are referred to herein as starboard hull 16 and as port hull 16a.

It will be understood that the port hull 16a of the float is the same as the starboard hull 16; it being noted that similar parts are designated by the same reference numeral with a sub-a added to the numerals referring to the port hull 16a.

Inasmuch as the two enclosed

hulls

16, 16a are of like construction, it is deemed sufficient to describe in detail only the starboard hull 16 as typical; it being understood that hull 16a is similarly constructed. The bow end comprises a cone 24 (see FIG. 6) upon which is mounted a hollow buoyancy body 25, this being contoured to merge with the cone 24 so that the fore end of the hull 16 has a contoured ship-shaped-bow 26. The portion 25 provides a closed air chamber 27. The closed air chamber 27 provides reserve buoyancy in the event of towing the floating unit 23 against waves, thus avoiding undercutting of the unit which could produce undesirable dynamic trimming. The cone chamber 28, at its aft end, communicates with the hollow elongate cylinder portion 30. A bulkhead 31 is mounted in the fore end portion of the cylinder 30, thus sealing off the chamber space 28 from the main chamber space 29 of the enclosed hull.

Abaft the bulkhead 31 and toward the stern end 32 is mounted a partial bulk head or baflle 33. The partial bulkhead 33 is inclined rearwardly from the topside segment of the cylindrical hull portion 30 (see FIG. 6) and terminates in a horizontal edge 34 which lies short of the bottomside segment of the hull (see FIGS. 6 and 9). Thus the bulkhead 33 closes a large portion of the circle of the cylinder but leaving an open passageway 37 bounded by the bulkhead edge 34 and the bottomside segment 35 of the hull, and the bulkhead provides, as described later on, a pocket space 36 abaft the partial bulkhead. The aft end portion of the hull cylindrical portion 30 is provided with a trough-shaped wall portion 38 which is deeper at its stern end and the trough inclines upwardly in forward direction and merges into the cylindrical wall portion of the hull a little forward of the inclined partial bulkhead 33. This trough shaped wall 38 provides a drainage pocket 39 and also serves as a guidance fin.

An air pressure conduit 40 extends through the wall of body 25 through the wall of cone 24 and through the forward bulkhead 31 and thence through the partial bulk head 33 and communicates with the air pocket space 36. The outer end of the compressed air line at 42 is suitably but removably connected to a flexible air pressure line 43 which extends to the power driven tow craft or tender (not shown), it being secured to the cable tow line 14 at spaced intervals by the clamps 44, the other end of which extends to the tender (not shown).

A vent pipe 46 extends from outside and through the wall portion 25 and passes through bulkhead 31 to provide communication between the chamber 29 of the hull with the ambient atmosphere, it being noted that the vent pipe 46 has a rearwardly extending outer end 47. The vent pipe is provided with a solenoid controlled valve 48 operative to open and close the vent pipe 46. The vent pipe is also provided with a one-way or check valve 45 which permits fluid (air) to flow in a direction out of chamber 29 but prevents flow in the other direction into chamber 29. If desired, the valve 48 may be located within the buoyancy body 25, where it is protected from the sea or weather. The vent pipe 46 is cross connected to air pressure conduit 40 by conduit at a place intermediate the solenoid valve 48 and check valve '45. An electric conductor cable 41 connected to the solenoid valve 48 extends through the air pressure conduit 43 to the tender so that the opening and closing of valve 48 may be controlled from the tender.

One or more openable and closeable solenoid controlled valves or sea-cocks 50 are mounted at the bottom and in the aft portion near the stern end of the cylindrical hull 30 to provide communication between the chamber 29 and the ambient sea 51.

An electric conductor cable 49 extends from the tender (not shown) through the flexible air pressure conduit 43, and conduit 40 to the solenoid valve 50 so that the opening and closing of the valve to open the chamber 29 to the ambient sea, or to close it, may be carried out and controlled from the tender.

A hollow tube 52 having a bent shape is mounted in the stem end of cylinder 30. One leg 53 of the tube extends through the bottom wall 38 of the trough and communicates with the ambient sea. The other leg 54 of the U-shaped tube extends into the trough 39 and terminates short of the bottom of the trough. The U-portion 55 of the tube terminates short of the topside wall of the cylindrical hull (see FIGS. 6, 7, 9, 10). A check valve 56 is provided in one leg of the U-tube 52. This permits passage of fluid (air or water) in only one direction through the tube 52, namely, from trough 39 to the ambient sea through leg 53.

A cross connection air pressure conduit 57, which may pass through the fore strong beam, is connected at one end 58 to conduit 40 in starboard hull 16 and at its other end 58a in port hull 16a to conduit 40a. This cross connection, while not necessary in all instances, is desirable in view of the fact that there are two flexible air pressure lines; one connected to the starboard hull and one to the port hull. It could happen that one flexible air pressure line could become clogged, for instance, when one flexible hose is bent or twisted. In such case, the ballast water in one of the hulls might not be properly drained, resulting in overturning the float, or result in not keeping the float on an even keel. By providing cross connection conduit 57, air pressure is evently distributed to both hulls and both hulls are symmetrically drained of ballast water during a docking operation A plurality of elastomer cross members 64 are secured at their outer ends to the

hulls

16 and 16a and spaced apart to form an elastomeric grid (designated generally by reference numeral 64x) upon which the submarine rests when in docked position on the float (see FIG And a resilient cushion pad 60 is mounted on strong beam 17 to minimize damaging impact when the submarine engages the strong arm during a docking operation.

Platforms or decks 61, 61a are mounted on the top sides of the

hulls

16, 16a intermediate the bow and stern (see FIGS. 2-5). These may be used by personnel boarding or leaving the submarine through the hatch 71.

Lights

62, 62a may be mounted on the hull for providing light when operations are carried out in the dark. Also, devices for ejecting acoustic or electronic beams from the two bows may be used for blind directional guidance during foggy weather.

Means are provided for lashing the submarine to the float, if that becomes necessary, or desirable. The submarine may be lashed to the float by suitable lines such as, for example,

hawser ropes

63, 63a, which may be secured to the submarine; the ends of the ropes being made fast at their outer ends to suitable tying means 65, 65a fixed to the

hulls

16, 16a. Visible float gauge marks 66, 66a are provided on the surface of the

bow portions

21, 21a to serve as index or reference marks which facilitate the determination of how much ballast is required in the flipping operation to move the float to vertical position and to a depth to .provide proper or desirable freeboard, and so that the strong beam 17 is submerged at proper depth.

In the following description, reference should also be made to FIG. 12, this figure being a schematic view illustrating the piping and electrical hook-up It will be understood that there is provided on the tender (not shown) a source of compressed air in tank 82 connected by conduit 83 to compressed air valve 84. This is a solenoid valve connected by electrical cable to a switch panel 85, also on the tender. It may be noted here that electric cables 41, 41a connected to solenoid

valve

48, 48a (see also FIG. 8), extend through flexible air pressure conduits 43, 43a to the switch panel 85 and electric cables 49, 49a, connected to

solenoid seacock valves

50, 50a, extend through air pressure conduits 43, 43a to the switch panel. All of the solenoid valves are preferably of the type which are closed as by .a spring actuator and are opened by actuation of their respective solenoids. It will be further noted that in FIG. 12 the electrical wires are shown diagrammatically for clarity in showing the elec trical hook-up.

As stated hereinbefore, the tow cable 14 (see FIGS. 6 and 12) extends to the tender (not shown) and the flexible air pressure conduits 43, 43a, also extending to the tender, are secured at intervals to the tow cable. Electrical cable connector means and fittings, known in the art, are provided on the tender at the ends of the

cables

41 and 49, these cables being connected to their

respective solenoid valves

48 and 50 as mentioned. The conductor cables extending through the flexible conduits 43, 43a are thus protected. Switch means located on the tender are provided for connection to the electric cables.

The float may be flipped from horizontal floating position, as illustrated in FIG. 8, to vertical submerged position, as illustrated in FIG. 6 in the following manner. Assuming the flipping operation is started when the float is floating in horizontal position when the water ballast 69 has been removed (see FIG. '8). By opening sea-

cock valves

50, 50a and

opening vent valves

48, 48a, water passes through the sea-cocks from the sea into chambers 29, 29a in the pair of

hulls

16, 16a. Air then in chambers 29, 29a may escape to the atmosphere through

vent pipes

46, 46a. The float then sinks to vertical position at a freeboard 70 (see FIG. 6). Ballast water is introduced until

marks

66, 66a, serving as an index, are at sea surface level (see also FIG. 3). This operation is brought about by rotating switch contact handle 86 clockwise (see FIG. 12) from normal position I to flooding position 11. When the contactor switch handle 86 is at station II, this closes circuit 87 to

solenoid valves

50, 50a and circuit 88 to solenoid vent

valves

48, 48a, which opens the sea-cocks and vent valves; air pressure valve 84 remaining closed. After the float receives suflicient ballast water from the sea, it is now in position to receive a submarine 10 for docking (see FIG. 1 and FIG. 6). The strong beam 17 (see FIGS. 3 and 6) is submerged below the surface a suitable distance with a freeboard 70, the

air chambers

27, 28 and 27a, 28a providing buoyancy to maintain the float submerged in vertical position but not further sinking. The submarine 10 approaches the float and the bottom portion 72 of the submarine contacts the strong beam 17; the resilient pad 60 serving to minimize any undue impact. When the submarine makes contact with strong beam 17, the system is ready to carry out the docking operation. Air under pressure is introduced from compressed air tank 82 on the tender, through the air pressure lines 43, 43a and 40, 40a, expelling water from the

hulls

16, 16a. This operation is brought about by rotating switch handle 86 clockwise to station IH on switch panel '85. This interrupts circuit 88 and solenoid vent valves are closed.

Valves

50, 50a, and air pressure valve 84 are opened, because circuits 87 and 88 are closed when the switch contactor 86 is at station III. Air first enters the

air pocket spaces

36, 36a (see FIGS. 6 and 12) and expels water from them. By virtue of the inclined partial bulkheads 33, 33a, a buoyancy wedge is produced causing a buoyancy force acting in the direction indicated by arrow 74 (see FIG. 7), with an effective lever arm length 75 relative to the point or pivot where the bottom 72 of the submarine is in contact with strong beam 17. This causes the system (the

hulls

16, 16a as a unit) to begin rotation about the strong beam as a fulcrum or pivot in a direction indicated by arrow 76 (see FIG. 3). The propulsion of ballast water causes the ballast to pass through open sea-

cocks

50, 50a and also causes water to pass from the open end of leg 54 of

bent tubes

52, 52a, and this passes into the sea through legs 53, 53a, producing jet forces, the resultant of which causes the

hulls

16, 16a to continue their swinging movement about the strong beam 17 as a fulcrum in direction of arrow 76, the fixedly connected hulls acting as a lever with an effective lever arm length indicated by arrow 77 (see FIG. 7).

After a certain rotation or inclination of the

hulls

16, 16a has been reached, as indicated in FIG. 7, the pocket buoyancy 36 produces a buoyancy force in the direction indicated by arrow 78, and the interface 79 between the water and air reaches the lower edge 34 of partial bulkhead 33. Now air enters the upper ballast space 29 as indicated by-arrow 80, while water from the upper ballast space flows toward the stern through the open passageway under the edge 34 of the bulkhead 33, it being understood that the

valves

50, 50a are in open position and vent

valves

48, 48a are in closed position at this time, and the Water is being ejected through legs 53, 53a of the

bent tubes

52, 52a and

valves

50, 50a to cause a. resultant jet force driving the stern end of the float upwardly about the strong beam 17 as a fulcrum. Meantime the chambers 29, 29a are being filled with buoyancy air and this further assists in the rotation of the float upwardly about the strong beam pivot toward horizontal floating position on the surface of the sea. It will be noted that during the expulsion of ballast water from the hulls, the

vent tubes

46 and 46a are closed by means of

solenoid valve

48, 48a.

Near to completion of de-ballasting, the last portion of ballast water is drained from the trough 39 and all may be removed, if desired, except that indicated by arrow 81. In some instances, it may be desirable to arrange the electrical hook-up in such manner that the

seacocks

50 and 50a be maintained in closed position during the entire upswinging operation of the float. When water is being expelled and the sea-cocks are closed, then the ballast water is expelled only through the

tubes

52, 52a.

While the float is being de-ballasted and is swinging upwardly about its strong beam pivot 17, to horizontal floating position on the surface of the sea, the elastomeric cross members 64 successively from fore to aft come into engagement with the bottom or belly 92 of the submarine in an orderly, smooth operating sequence, until the submarine is resting on the elastomeric grid 64x provided by the cross members 64 (see FIG. 4). Sufficient water is removed so that the weight of the submarine is carried partly by its own buoyancy and the balance by the buoyancy provided by the

de-ballasted hulls

16, 16a, with the bulls in trim condition.

The submarine now having been docked, the switch contact handle 86 (FIG. 12) is rotated clockwise to station I. This interrupts all electric circuits and all solenoid valves are closed. The float and submarine is now ready for towing as a unit. If it is necessary or desirable, it may be lashed to the float by

ropes

63, 63a. The float and docked submarine may now be towed by the tow cable 14 secured at the tender. When docked, the submarine may be boarded from the platforms 60, 60a or personnel may disembark therefrom.

T o disengage the docked submarine from the float, the flooding operation is then carried out by rotating the handle switch 86 clockwise to station II, on the switch panel 85, as described in the foregoing.

A modified form of enclosed hull 116 is illustrated in FIG. 11, which is simpler in construction. This form of hull connected as a pair in the fashion of a catamaran, as described in the foregoing, may be used in instances where the more sophisticated form is not required. A typical hull 116 of the pair of hulls is connected in the fashion of a catamaran as the more sophisticated form described in the foregoing and the float is provided with an elastorneric grid, such as grid 64x (see FIG. 4). The hull 116 comprises a cylindrical body portion connected to a cone portion 124 on which is mounted a buoyancy body portion 125. A bulkhead 131 is mounted intermediate the bow end 126 and the base end of the cone portion 124. This separates the enclosed hull into a sealed

air chamber space

127, 128 and a ballast chamber 129; the

air chamber

127, 128 will maintain a free board 170 when the float is in submerged vertical position. To flip this float to submerged vertical position from horizontal floating position, the sea-cock 150' is opened and water enters into ballast chamber 129 from the sea. The terminal end 136 of the compressed air conduit 140 is positioned a distance 137 from the closed stern end of the hull. When water enters through valve 150, the compressed air line 140 is kept closed, so the air in space 129 is compressed sufliciently to permit suflicient ballast water 180 to occupy the ballast chamber 129 to flip the bull to vertical submerged position as illustrated in FIG. 11. This leaves a buoyancy space containing compressed air from the interface 139 between the water and air, to the bulkead 131. To carry out a docking operation, that is, to de-ballast and rotate the hull 116 to horizontal position, solenoid sea-cock 150 is opened, this being connected by electric cable 149 to a suitable source of power and switch means on the tender. This introduces compressed air into ballast chamber 129 and expels ballast water 180 into the sea through valve 150. When suflicient ballast Water is expelled to swing the hull to horizontal, floating position on the sea during the docking operation, valve 150 is closed, the compressed air valve is then closed, and the hulls, as a unit, are ready for towing. It will be understood, of course, that two hulls similar to hull 116 are connected together by strong cross beams in catamaran fashion, as described in the foregoing, to provide a complete float to be towed by cable 114. Such a system requires less air for de-ballasting by virtue of the compressed air in chamber 129 and otherwise simplifies construction, although it will be manifest that the structure shown in detail in the other figures will be more desirable and preferred because of the additional advantageous features.

The float has been described in connection with its use as a docking and towing float for a submarine, but in the light of the foregoing description, it will be realized that the float is not limited to docking and towing of small submarines to open sea, but it may be designed as to size and contrived for salvage and rescue Work for larger or other surface and subsurface vehicles or craft. For example, it may be designed for rescue-towing of navalcraft up to the size of small destroyers, preferably in the event of damage stability cases.

The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention.

What is claimed is:

1. A towable float for docking and towing seacraft comprising at least two elongated hollow bodies, each having a bow end and a stern end, a rigid, fore strong beam connected at its outer ends to said bodies near the bow ends of said bodies, a rigid, aft strong beam connected at its outer ends to said bodies near the stern ends of said bodies, said beams and bodies being connected in catamaran fashion and forming a rigid unit which floats when placed in a body of water, a bulkhead located in the forward end portion of each of said hollow bodies, providing a buoyancy chamber in the bow ends of each of said bodies and a ballast chamber abaft each of said bulkheads, sea-cock valves through which ballast water may be introduced into and expelled from said ballast chamber, said buoyancy chambers causing said unit to float with a freeboard observable above the level of the body of water when said ballast chambers contain suflicient water to sink the stern ends of said hollow bodies, said seacock valves being located in the stem end portions and in the bottom walls of said bodies, means for introducing compressed air into said ballast chambers for expelling ballast water from said ballast chambers including a conduit connectable to a source of compressed air, said conduit extending from outside said bodies to a location in the stern end portion of said ballast chambers, means connected to said sea-cock valves controllable from outside said hollow bodies for opening and closing said sea-cock valves, and means connected to said conduit controllable from outside said bodies for causing compressed air to pass through said compressed air conduits into said ballast chambers for expelling ballast water therefrom, a grid connected with said bodies and extending across the space between said bodies, said bodies sinking to upright position with said fore strong beam below the Water level and said bow ends extending above the water level of the body of water with sufficient free board to be observable, when ballast water is introduced into said ballast chambers, said fore strong beam serving as a pivot about which said unit may be swung when the seacraft is in contact therewith and floating on the body of water, said elongated hollow bodies swinging upwardly about the fore beam as a pivot to substantially horizontal position with the grid contacting the under side of the seacraft when ballast water is expelled from said ballast chambers.

2. A docking and towing float comprising a pair of elongated hollow buoyancy bodies referred to hereinafter as hulls, each having a bow end and stern end, a strong, rigid, fore main cross beam connected at its outer ends to said hulls near the bow ends of said hulls, a strong, rigid, aft main cross beam connected at its outer ends to said hulls near the stern ends of said hulls, said beams and hulls being connected in catamaran fashion and forming a rigid unit, the bow ends of said hulls being in the general shape of a cone, buoyancy bodies at the fore ends of said hulls contoured to form ship-shaped bows, a main bulkhead in each of said hulls aft of said ship-shaped bows and providing an enclosed buoyancy air chamber in each of said hulls at their bow ends and a ballast chamber in each of said hulls abaft said main bulkheads, cross members secured to each of said elongated hollow bodies and positioned between said fore and aft main beams, sea-cock valves located in the stern end portions of said ballast chambers through which ballast water may be introduced into and expelled from said ballast chambers, an inclined partial bulkhead baflle in each of said ballast chambers aft of said main bulkheads providing a pocket abaft each of said baffies and a passageway beneath each baflle for ballast water to pass therethrough in a direction toward said how ends and in a direction toward said stern ends, a compressed .air conduit in each of said ballast chambers terminating in said pockets and extending to outside of said ballast chambers and connectable to a source of compressed air, control means connected to said sea-cock valves controllable from outside said hulls for openings and closing said sea-cock valves, and control means connected to said compressed air conduits controllable from outside said hulls for causing compressed air to pass through said compressed air conduits into said pockets for expelling ballast water from said ballast chambers.

3. A float as defined in claim 2, in which said cross members between said fore and aft main beams are elas tomeric and form a grid upon which an object to be towed may be supported.

4. A float as defined in claim 3, including a vent pipe in each of said hulls terminating in said ballast chambers abaft said main bulkheads and extending to outside of said hulls.

5. A float as defined in claim 4, in which an openable and closeable vent Valve is connected in each of said vent pipes.

6. A float as defined in claim 5, which includes control means connected to said vent valves controllable from outside said hulls for opening and closing said vent valves.

7. A float as defined in claim 6, in which a check valve is provided in each of said vent pipes permitting flow through said vent pipes and valves in a direction away from said ballast chambers but not in a direction toward said ballast chambers.

-8. A float as defined in claim 7, in which each hull at their stern end portions has a guidance fin on its bottom wall providing a trough in the stem end of each ballast chamber.

9. A float as defined in claim 8, which includes a curved drainage pipe in each of the stern end portions of said ballast chambers, each of said curved pipes having two legs and a check valve connected therein, one of said legs extending through the bottom wall of the trough and the other of said legs terminating within its ballast chamber near its bottom wall, said check valves in said drainage pipes permitting fluid flow through said pipes only in a direction from the ballast chambers.

10. A float as defined in claim 7, in which a cross over conduit is connected at one of its ends to the air pressure conduit in one of said hulls and at the other of its ends to the air pressure conduit in the other of said hulls, each end of said cross over conduit being connected to the vent pipe between the check valve and the openable and closeable vent valve.

11. A float according to claim 7, which includes a guidance fin at the stern end portions of each of said hulls on the bottom side providing a drainage trough in each of said ballast chambers, a curved drainage pipe in the stern portions of each of said ballast chambers, each of said curved pipes having two legs and a check valve connected therein, one of said legs extending through the bottom wall of the trough and the other of said legs terminating within its ballast chamber near the bottom wall of its trough, said valves in said drainage pipes permitting flow through said drainage pipes only in a direction from said ballast chambers.

12. A float for docking and towing a seacraft in the opentsea or other waters, which comprises two elongated hollow bodies, hereinafter referred to as hulls, each having a bow end and a stern end; a strong, rigid, fore cross beam connected at its outer ends to said hulls .near the bows of said hulls; a strong, rigid, aft cross beam connected at its outer ends to said hulls near the stern ends of said hulls; said hulls and strong cross beams being connected in catamaran fashion and forming a rigid unit; the bow ends of said hulls each comprising a cone shaped hollow body having a hollow buoyant body mounted atop the cone shaped body and contoured to form a shipshaped bow; a main bulkhead in each of said hulls near the base ends of said cones providing an enclosed buoyancy air chamber in each of said bows and a ballast chamber abaft each of said main bulkheads; a plurality of elastomeric cross members connected to said hulls between said fore and aft strong beams forming an elastic grid for supporting the seacraft, solenoid sea-cock valves located in the stern end portions of each of said ballast chambers through which ballast water may be introduced from the sea into said ballast chambers and through which ballast water may be expelled therefrom into the sea through the bottom walls of said chambers; an inclined partial bulkhead baflle in each of said ballast chambers aft of said main bulkheads and located in the stern end portions of said ballast chambers providing a pocket abaft each of said baflles and a passageway under each baffle through which ballast water may pass in a direction toward said bow ends and in a direction toward said stern ends of said ballast chambers; a compressed air conduit in each of said ballast chambers terminating in the pocket abaft the partial bulkhead and extending to outside of said hulls and connectable to a source of compressed air outside of said hulls; a solenoid compressed air valve connected in the compressed air conduits operative to open and close said compressed air conduits; electric cables connected to said solenoid compressed air valves extending to outside said hulls and connectable to switch means outside said hulls for operating said sea-cock valves; air vent conduits in each of said hulls extending from the fore end portions of said ballast chambers to outside said hulls, said air vent conduits having a check valve prohibiting flow in a direction toward the ballast chambers and permitting flow in the opposite direction; solenoid air vent valves in said vent conduits operative to open and close said vent conduits; electric cables connected to said air vent solenoid valves and extending to outside of said hulls and connectable to switch means outside of said hulls for operating said air vent solenoid valves; said hulls being sinkable to vertical position when suificient ballast water is introduced into said ballast chambers with said fore strong cross beam submerged to a predetermined depth below the sea surface; said fore strong beam, when the bottom portion of the seacraft being docked is in engagement therewith, serving as a fulcrum around Which said hulls may be swung upwardly from vertical position to horizontal floating position on the sea surface with said grid in engagement with the bottom of the seacraft, by introducing compressed air into said ballast chambers and expelling ballast Water from said ballast chambers.

13. A float according to claim 12, in which a boarding platform is mounted atop at least one of said hulls.

14. A float according to claim 12, including means secured to the float for lashing thereto a submarine resting on said grid.

15. A float according to claim 12, which includes lights References Cited UNITED STATES PATENTS 2,614,518 10/1952 Carter 114-53X 2,754,790 7/1956 Wiggins 114 s3 TRYGVE M. BLIX, Primary Examiner.

US. Cl. X.R.

for facilitating the docking of a submarine to said float 10 114-44 in obscure weather conditions.