GB2578492A

GB2578492A - A device for attaching to a target

Info

Publication number: GB2578492A
Application number: GB1904390.0A
Authority: GB
Inventors: Jones Roy
Original assignee: ECS Special Projects Ltd
Current assignee: ECS Special Projects Ltd
Priority date: 2019-03-29
Filing date: 2019-03-29
Publication date: 2020-05-13
Anticipated expiration: 2039-03-29
Also published as: GB201904390D0; GB2578492B

Abstract

A device 100 for attaching to a target, such as an item of underwater item of unexploded ordnance (745, figure 6), comprising an attachment means 400, such as a nail gun, for attaching to the target and a releasable connection means 130 for connecting to a carrier 110, such as a UUV (760),where the connection means automatically releases after the attachment means attaches to the target. In some embodiments there is an exhaust vent 580 through the side wall of a barrel 510 of the attachment means. In some embodiments there are a plurality of such devices mounted to a single carrier

Description

A Device for Attaching to a Target

Field of the Invention

The present invention relates to a device for attaching to a target. More specifically the present invention relates to a device for attaching to an underwater object, such as an item of unexploded underwater ordnance.

Background to the Invention

Underwater historic unexploded ordnance (Ux0) is a major nuisance in offshore construction operations, such as the construction of offshore wind farms or the laying of sea floor cables or pipelines. The possibility of Ux0 in a construction area 113 necessitates taking a detailed survey of the seabed before construction can begin.

Often Ux0 can be discovered at or near to the sight of a planned offshore construction operation or can be discovered near existing offshore assets such as underwater communication cables or oil pipelines.

The usual process is to survey the seabed in the area using sophisticated side-scan 15 sonar and magnetometer equipment from a dedicated underwater vehicle. When a positive indication of an item of Ux0 occurs, its coordinates are logged for future identification, analysis and disarmament or disposal.

The logged Ux0 must subsequently be relocated before it can be disarmed and removed or disposed of by an underwater ordnance disposal system. However, the relocation of Ux0 which has been located and logged in an initial survey is time consuming and imprecise as items of Ux0 may have been moved from their logged locations by ocean currents and/or may have been partially or completely covered resettled silt since the initial survey.

Subsea communication acoustic pingers' or beacons, sometimes referred to as tags, may be attached to identified items of Ux0 when they are initially located in order to facilitate their subsequent relocation.

Known methods of disposing of unexploded underwater ordnance include traditional mine sweeping vessels which drag either lines for mechanically triggering the ordnance or a decoy to remotely trigger the ordnance (such as by simulating the magnetic or acoustic signature of a vessel being targeted by the ordnance).

This type of minesweeping is dangerous, as it requires the vessel to enter the area containing the ordnance. Additionally, some ordnance is 'unsweepable' and has been modified to prevent the use of such a system, and/or ordnance may be adjacent to structures such as oil or gas pipelines which would be damaged by detonating the ordnance.

Other known systems enable disposal of unexploded underwater ordnance remotely from a vessel (such as a mine countermeasures vessel (MCMV)). These include diver placed charges, remotely operated single charge systems, or multiple charge deployment systems.

Divers may attach charges to items of unexploded ordnance by rope, mechanical fixings, or other means, and may be triggered by timers, flash exploders, or other means. Clearing an area with driver placed charges is time consuming and inherently dangerous to the divers.

Remotely operated single charge systems are typically sacrificial single charge 'one-shot' remotely operated vehicles (ROVs) which are detonated to reliable detonate items of unexploded ordnance. Using these systems is safer than a driver placing charges, as no diver is required to enter the area containing the unexploded ordnance.

Remotely operated multiple charge deployment systems enable multiple charges to be placed separately onto different items of unexploded ordnance in a single mission. Known systems ROVs with multiple shaped charge disruptors and attachment means on a series of extending arms, these systems have a limited ability to accurately place the disruptors due to the bending forces on the arms supporting the attachment devices and disruptors when extended.

Another known system is an ROV carrying a single charge to be deployed, the system simultaneously releases the charge from the ROV and activates an attachment means for attaching the charge to an item of unexploded ordnance. However, the attachment means may fail to securely attach the charge to the item of ordnance, resulting in the charge becoming lost and difficult, if not impossible, to recover.

European Patent Application EP3179202 (Al) (SAAB DYNAMICS AB) discloses a system for attaching a device to an item of underwater ordnance, comprising a means for attaching the device to the item and a means for releasably coupling the device to a deployment system which is changeable between configurations in which the device is flexibly and rigidly coupled to the deployment system.

An aim of the present invention is to provide an improved means for attaching devices such as acoustic pingers or disposal charges to items of underwater unexploded ordnance.

Summary of the Invention

According to a first aspect of the present invention there is provided a device for attaching to a target, the device comprising: an attachment means for attaching to a target and a releasable connection means for connecting the device to a carrier, wherein the connection means is automatically released after the attachment means attaches to a target.

The device is preferably for attaching to underwater targets and more preferably is for attaching to underwater items of unexploded ordnance, such as a historic mines or bombs. Alternatively, or additionally, the device may be for attaching to marine vessels such as ships or submarines and/or to underwater structures or underwater portions of structures such as wrecks, rocks or bridges. The device and the attachment means thereof are preferably for attaching to any of a plurality of targets.

The device may advantageously be used to attach a payload, which may be comprised by, supported by, or connected to the device, to a target. For example, the device may be used to attach a beacon or an acoustic pinger to an underwater target item of unexploded ordnance in order to facilitate the subsequent relocation of that item.

The device may be elongate and/or may be generally or substantially cylindrical or may comprise an elongate and/or generally or substantially cylindrical portion. The attachment means and the connection means are preferably at opposite ends of the device and/or of an elongate and/or cylindrical portion thereof.

For example, the device may comprise an elongate cylindrical body with the attachment means at its first end and the releasable connection means at its distal second end; the device may optionally further comprise a payload which may be located within, or may be connected to, the cylindrical elongate body intermediate the first and second ends.

The attachment means is preferably for partially extending a nail from the device and/or for driving a nail partially into a target. The attachment means may partially extend a nail from the device and/or drive the nail partially into the target in use and may thereby nail the device to the target and attach it thereto. For example, the attachment means may be or may comprise a nail gun or other means for at least partially extending a nail out of the device.

The attachment means preferably retains the head of the nail within the device, this may ensure that the device remains connected to the nail and thereby to any target into which the nail is driven.

In some embodiments the attachment means drives or extends the nail through a wall or other portion of the device in use. The attachment means may be for driving and/or extending the nail through a wall or other portion of the device and partially out of the device and/or partially into the target. In use, the nail may be extended from within the device and may pierce the wall or other portion, before extending outward from the device and/or into the target. The wall or other pierced portion may thereby be trapped between the target and the head of the nail, thereby nailing the device to the target.

The wall or other portion of the device which is pierced by the nail may be formed from a softer material than the remainder of the device, such as from rubber or another elastomer.

In some embodiments, in use the attachment means drives and/or extends the nail away from the connection means and/or outward from and end of the device or a portion thereof. The attachment means may be for extending and/or driving the nail away from the connection means and/or outward from and end of the device or a portion thereof For example, in embodiments wherein the attachment means and the connection means are at opposite first and second ends of the device respectively, the attachment means may be for extending the nail lengthways outwards from the first end in a direction away from the second end.

In preferred embodiments the nail is extended from the device and/or driven into the target in use by the detonation of an explosive charge, such as a chemical propellant charge. For example, the attachment means may be or may comprise a power-actuated nail gun (a nail gun actuated by a controlled explosion).

The explosive charge may be a cartridge which may be comprised or received by the device and/or attachment means thereof. The cartridge may comprise a primer which may be detonated in use by the attachment means; for example, by a firing pin comprised by the attachment means. Alternatively, the explosive charge may be a gas explosive charge.

The detonation of the explosive charge may release the connection means. Detonation of the explosive charge may therefore cause the nail to be driven into the target and the connection means to be released. For example, in use, expanding gasses from the detonation of the explosive charge may displace a component of the connection means in order to actuate it to release (in addition to driving the nail into the target).

The detonation of the explosive charge preferably only releases the connection means after the nail has been extended from the device and/or driven into the target. Expanding gasses from the detonation of the explosive charge may be blocked from reaching and actuating the connection means until after the nail has been extended from the device and/or driven into the target in use. For example, the expanding gasses may only be able to reach and actuate the connection means via an exhaust vent near the far end of the barrel from the explosive charge, the exhaust vent being blocked by a piston attached to the head of the nail until the piston is driven to the far end of the barrel by the expanding gasses (at which point the nail attached to the piston will have been driven outwards from the device).

In alternative embodiments, the nail may be extended from the device and/or driven into the target in use by compressed gas (for example, wherein the attachment means is or comprises a pneumatic nail gun), by one or more electromagnets (for example, wherein the attachment means is or comprises solenoid-powered nail gun). In embodiments where the nail is driven or extended by compressed gas, the compressed gas may be provided from a reservoir or pre-compressed air such as a replaceable capsule of compressed gas; alternatively, the compressed gas may be provided form an external source such as from the carrier.

In preferred embodiments, the attachment means comprises a barrel, within which the nail may be held before being extended from the device and/or driven into the target and along which the nail may be driven in use.

The attachment means may further comprise a piston which is preferably located within and slideable along the barrel, and which is preferably arranged to drive the nail as it is slid along the barrel. The piston is preferably connected to, and more preferably contains or defines the head of the nail, the nail will therefore be driven with the piston but will not be entirely displaced out of the device. The piston defines a barrier across substantially the entire cross section of the barrel, such that expanding gasses (for example from detonation of the explosive charge or from a compressed gas source) are unable to pass the piston. The piston may comprise an indent, such as a generally hem i-spherical indent, facing towards the source of the expanding gasses.

The attachment means may further comprise a nail guide, such as a washer, which may fit around the shaft of the nail and preferably aligns the shaft with the central axis of the barrel. The nail guide is preferably slideable along the barrel and/or along the shaft of the nail, such that when the nail is driven along the barrel, it does not prevent the nail from sliding along the barrel or out of the device.

The attachment means preferably comprises one or more exhaust vents which are preferably formed through side walls of the barrel and the expanding gases are preferably only able to exit the barrel through them after the piston has been slid past them. The exhaust vents are preferably arranged towards the end of the barrel distal from the source of the expanding gasses (such as an explosive charge) such that the expanding gasses are only able to exit the barrel through them after the piston has been slid the majority of the way along the barrel.

In particularly preferred embodiments the exhaust vents are arranged such that the expanding gasses are only able to exit through them after the piston has been slid substantially to the furthest point from the source of the expanding gasses along its path of travel (for example, when the piston is against the end of the barrel or is pressing the head of the nail and/or the nail guide against the end of the barrel).

The exhaust vents may be between the barrel and an expansion chamber (which may be a cavity in the shape of an annular cylinder surrounding the barrel) and may be between the barrel and a pathway to the releasable connection means (which may comprise the expansion chamber).

In preferred embodiments the attachment means is displaceable with respect to the connection means and the attachment means is actuated to attach to the target by displacing the attachment weans with respect to the connection means. For example, the attachment means may be actuated to drive a nail into the target and/or to extend a nail from the device by displacing the attachment means with respect to the connection means.

Preferably the attachment means is actuated to attach to the target by displacing the attachment means towards the connection means. In such embodiments the attachment means may be actuated by pressing it against the target.

The attachment means may be actuated when it has been displaced past a threshold 15 with respect to or towards the connection means.

In preferred embodiments the attachment means is displaceable along a single axis, the axis preferably being parallel to the length of the device, or a portion thereof. For example, in embodiments where the attachment means and connection means are at opposite ends of an elongate device, the attachment means may be displaceable along a lengthways axis towards and away from the connection means.

The device preferably comprises a means biasing the attachment means away from the connection means, such as a spring or other resiliently deformable means. In use such a biasing means may be overcome by pressing the attachment means against the target. The attachment means may be actuated when it displaced a threshold distance from its resting position in the direction against the biasing means.

Displacing the attachment means with respect to or towards the connection means may actuate the attachment means by detonating an explosive charge as described above.

In preferred embodiments the device comprises a hammer and a firing pin, the 30 hammer being arranged to be driven to impact the firing pin when the attachment means is displaced with respect to or towards the connection means or is displaced to a threshold with respect to or towards the connection means. The firing pin preferably being arranged to detonate the explosive charge when the hammer impacts it.

The firing pin is preferably held against the explosive charge of the attachment means and may be comprised by or displaced with the attachment means. In some embodiments the hammer is displaced with the attachment means until the displacement means is displaced past a threshold at which the hammer is driven to impact the firing pin. For example, the hammer may be biased towards the firing pin by a spring but separated from the firing pin by a separation means (such as a rod) which maintains a minimum separation between the firing pin and the hammer until the attachment means is displaced past a threshold. After the attachment means is displaced past the threshold the separation means is preferably displaced (for example, out of the path of the hammer or into a hole within the hammer) such that the hammer is free to be driven towards or into the hammer by the means biasing it.

The hammer preferably thereby impacts the firing pin or a component of the device (such as the separation means) which is in contact with the firing pin.

In a particularly preferred such embodiment, the hammer comprises an indent or hole in an end facing towards the firing pin and the separation means is a rod extending between the firing pin and the end of hammer and in use displaces the hammer with the firing pin (and by extension the attachment means) until the attachment means is displaced to a threshold. When the attachment means is displaced to the threshold, an end of the separation rod is preferably displaced form the end of the hammer into the indent or hole therein, allowing the hammer to be driven towards the firing pin by its biasing means (such as a spring) until the base of the indent or hole impacts the end of the separation rod (or alternatively, the hammer impacts the firing pin), the hammer thereby impacting the firing pin. The end of the separation rod may be displaced into the hole or indent by an at least partially tapered aperture through which it extends contacting a tapered portion of the separation rod.

The firing pin, hammer, and/or the separation means are preferably arranged or biased to return to resting positions when the attachment means is returned to a resting position (for example, by displacing it away from the connection means).

The device may comprise means for locking the attachment means against displacement with respect to or towards the connection means. For example, the device may comprise a gap, indent or groove between the attachment means and the connection means (or another portion of the device fixed with respect to the connection means), the width of the gap preferably being variable in size as the attachment means is displaceable with respect to the connection means. A clip or other object may be inserted into the gap so as to prevent displacement of attachment means and unintentional actuation of the attachment means.

The device comprises a releasable connection means which is automatically released after the attachment means attaches to a target. Preferably the connection means is automatically released after the attachment means is operated in such a manner that it would attach to a target if the target is adjacent the attachment means. For example, in embodiments wherein the attachment means attaches to a target by extending nail into the target, the connection means is preferably automatically released when a nail is extended (regardless of whether the nail is extended into a target or not).

Preferably the releasable connection means is not automatically released unless the attachment means has been operated as described above. The releasable connection means is preferably also manually releasable.

The releasable connection means for connecting the device to the carrier is preferably for retaining at least part of the device within a socket. The socket preferably being comprised by or supported on the carrier.

The carrier may be or may be comprised by a remotely operated vehicle (ROV), preferably a remotely operated underwater vehicle. For example, the carrier may be a frame comprised or held by the skid of an ROV.

The releasable connection means preferably comprises one or more retractable projections for engaging with one or more indents or recesses comprised by the carrier, or preferably with one or more indents or recesses on the interior of the socket. The connection means preferably releases by retracting the one or more retractable projections partially or entirely into the device and/or into itself.

The connection means is automatically released after the attachment means attaches to a target. For example, the connection means may be automatically released after a nail has been extended from the device by the attachment means.

Additionally, the connection means may be manually actuatable to release (for example, by retracting the one or more retractable projections partially or entirely into the device and/or into itself) or to engage or connect (for example, by extending the one or more retractable projections out of, or outwards from, the device and/or from itself). For example, the connection means may comprise a knob, lever, switch or other means for manually actuating the connection means.

The connection means is preferably arrangeable in a releasing configuration (for example, in which the one or more retractable projections are retracted) and in a connecting configuration (for example, in which the one or more retractable projections are extended). When the connection means is released (for example, automatically after the attachment means attaches to a target) the connection means preferably switches from the connecting configuration to the releasing configuration and when the connection means connects or engages, preferably switches from the releasing configuration to the connecting configuration.

In preferred embodiments the connection means is actuated to release after the attachment means attaches to the target by expanding gasses from the attachment means. The expanding gasses preferably being expanding gasses from the source of expanding gasses that drive and/or extend the nail (such as an explosive charge as described above) and more preferably are expanding gasses from the source that are able to reach the connection means after the nail has be driven or extended (such as expanding gasses exiting the barrel of the attachment means via exhaust vents after the piston of the attachment means has been slid past the vents by the expanding gasses).

In some embodiments the connection means comprises a chamber to which the expanding gasses from the attachment means pass and within which a piston is arranged to actuate the connection means to release when displaced by an increase in pressure within the chamber.

For example, an increase in pressure displacing the piston may displace a locking component (such as a locking means or shaft), or a wider portion thereof, out of a cavity into which open one or apertures within which the one or more retractable projections are located. The locking component, or wider portion of thereof being arranged to contact the bases of the one or more retractable projections and press them outwards when it is within the cavity. The device preferably comprises a manual means, such as a knob which may be depressed to displace the locking component back into the cavity. The device may comprise one or more spring loaded pins arranged to engage with one or more grooves or indents on the locking component and prevent it or its wider portion being displaced into and/or out of the cavity unless sufficient force is applied to it.

In preferred embodiments the device comprises, contains and/or is connectable to a payload. For example, the device may comprise a chamber for receipt of a payload or a payload connector for connection to a payload.

In some embodiments the payload is contained within a substantially cylindrical housing arranged substantially parallel to a main elongate substantially cylindrical body of the device comprising the attachment means and the connection means (preferably at opposite end of the body). The payload housing may be connected to the main body by a payload connector comprising two substantially parallel cylindrical apertures through which the main body and the payload connector may extend. The substantially cylindrical main body and the substantially cylindrical payload housing preferably having substantially equal radii.

The payload may be or may comprise, an acoustic pinger, a beacon, an explosive charge, a deployable radio frequency buoy, a spoofing device, and/or any other device 25 for attaching to an underwater item, such as an item of unexploded ordnance or a marine vessel.

According to a second aspect of the invention there is provided a system comprising: a carrier, and one or more devices according to the first aspect of the invention as described above; the one or more devices being releasably connectable to the carrier with their releasable connection means.

The carrier may be, and/or may be comprised by a frame, a skid, or a remotely operated vehicle (ROV), such as a remotely operated underwater vehicle. The carrier preferably comprises one or more sockets, each for retaining at least part of one of the one or more devices.

In preferred embodiments the one or more devices are a plurality of devices. One, some, or all of the one or more devices may have any of the optional features described above with reference to the first aspect of the invention.

The plurality of devices are preferably connectable (and more preferably only connectable) such that they are offset with respect to each other and extend different distances in a direction parallel to their lengths. For example, when multiple devices are connected to the carrier, the devices are preferably arranged parallel to and are offset lengthwise with respect to each other. This may allow the furthest extending device to be pressed against a target and connected thereto without the other devices contacting the device. For example, the carrier may comprise a plurality of parallel sockets which are offset from each other in the direction parallel to their lengths Preferred embodiments of the invention will now be described, by way of example, with reference to the Figures.

Brief Description of the Figures

Figure 1 is a sectional view of a device according to the first aspect of the invention received by a socket; Figure 2A is a sectional view of the device of Figure 1 being prepared for loading into a socket; Figure 2B is a sectional view of the device of Figure 1 after being received by the socket; Figure 3A is a sectional view of the device of Figure 1 being pressed against a target; Figure 3B is a sectional view of the device of Figure 1 after attaching to the target and disengaging from the socket; Figure 4A is an overall view of the device of Figure 1 with a payload; Figure 4B is an overall view of a carrier frame supporting a plurality of the devices of Figure 1 with payloads; Figure 5A a plan view of the carrier and devices of Figure 4B; Figure 5B is a partially exploded overall view of an underwater remotely operated vehicle comprising the carrier of Figure 4B; and Figure 6 is a diagram of an operation being performed using the remotely operated vehicle of Figure 5B.

Detailed Description of the Figures

Referring to the Figures generally there is shown a device 100 for attaching to a target item of underwater unexploded ordnance 700 according to the first aspect of the invention, as well as a system comprising a plurality of such devices 100.

The device 100, which is shown in detail and in various configurations in Figures 1 to 3B, is elongate and substantially cylindrical and comprises an attachment housing 400 at a first front end, a release housing 130 at a second rear end, and a hammer housing 300 intermediate the attachment housing 400 and the release housing 300.

The attachment housing 400 comprises a removable barrel housing 500 and an exhaust sleeve 600 and comprises means for attaching to a target 700 such as an item of unexploded underwater ordnance 745. The release housing 130 comprises means for engaging with a socket 110 such that the rear end of the device 100 is retained within the socket 110. The socket 110 being comprised by the frame 170 of the skid of a Remotely Operated Vehicle (ROV) 760. The attachment housing 400 is displaceable with respect the remainder of the device 100 and the hammer housing 300 comprises means for actuating the attachment means when the attachment housing 400 is depressed rearwards.

The release housing 130 comprises a first cylindrical body section at its front end (the end closest to the attachment housing 400) and a shorter narrower cylindrical tail section 135 at its rear end (at the rear end of the device 100). The tail section 135 being for fitting into the socket 110 and comprising a slightly tapered rear end for facilitating its insertion into the socket 110. A shoulder is defined between the tail section 135 and the body section which in use contacts the side of a socket 110 receiving the tail section 135.

An elongate cylindrical bore 220 is formed through the entire length of the release housing. The elongate bore 220 comprises a wider portion, which extends from the front end of the release housing 130 to a face 230 within and proximate to the rear end of the body section, and a narrow portion, extending from the face 230 through the tail section 135 to the rear end of the release housing 130. The bore 220 contains a locking knob 115, a release shaft 140, a release spring 200 and a portion of the hammer housing 300.

A plurality of holes 150 are formed through the wall of the tail section 135, between the bore 220 and the exterior of the device 100. The holes 150 each contain a spherical locking ball 120 with a greater diameter than the thickness of the wall of the tail section 135 through which the holes 150 are formed.

The balls 120 are displaceable between an arrangement where they protrude from the holes 150 outwards from the tail section 135 of the release housing 130 (wherein the release housing 130 is in a locking configuration, as shown in Figures 1, 2B and 3A) and an arrangement where they protrude inwards from the holes 150 into the bore 220 and do not protrude outwards from the tail section 135 (wherein the release housing 130 is in an unlocking configuration, as shown in Figures 2A and 3B).

The socket 110 is cylindrical and has a radius substantially equal to the radius of the tail section 135 of the release housing 135, such that the tail section fits into the socket 110. An annular groove 160 is formed in the interior cylindrical wall of the socket 110; the width of the groove being substantially equal to the diameter of the holes 150 in the tail section 135 of the release housing, and the distance between the groove 160 and an open end of the socket 110 being substantially equal to the distance between the holes 150 and the shoulder between the tail section 135 and the body section of the release housing 130.

The balls 110 are arranged to protrude into and engage with the groove 160 when the tail section 135 is inserted into the socket 110 and they are arranged and locked within the locking configuration. The balls 120 thereby prevent the tail section 135, and by extension, the release housing 130 and the device 100 in its entirety, from being displaced out of the socket 110.

The balls 110 are displaced between the locking configuration (shown in Figures 1, 2B and 3A) and the unlocking configuration (shown in Figures 2A and 3B) and are at times locked within the locking configuration by the movement and arrangement of the release shaft 140 and the locking knob 115 within the bore 220 of the release housing 130.

The locking knob 115 fits into and protrudes from the rear end of the bore 220 and has a diameter substantially equal to the narrower portion of the bore 220 through the tail section of the release housing 130. The locking knob 115 is displaceable lengthways within the narrower portion of the bore 220 between a first forward arrangement which it is located within in the locking configuration and a second rearward arrangement which it is located within in the unlocking configuration.

In the first forward (locking) arrangement, the locking knob 115 is held forwards and extends from outside the rear end of the bore 220, into the bore and past the holes 150. In this forward arrangement, the locking knob 115 covers the inside openings of the holes 150, such that the balls 120 are forced into their locking configuration. In the second rearward (unlocking) arrangement, the locking knob 115 is held rearwards and the locking knob extends from outside the rear end of the bore 220 to a point between the rear end of the bore and the holes 150.

An indent in the first end of the locking knob 115 (the end within the bore 220 closest to the first end of the device 100) receives the end of the release shaft 140, which extends from the locking knob 115 into the wider portion of the bore 220. The rear end of the locking knob 115 comprises a groove defined by a flange to facilitate its gripping by a user.

The release shaft 140 is generally cylindrical and comprises a flange 210, a wider length with a first greater radius and three narrower lengths with equal second smaller radii. The three narrower lengths extending from the rear end of the shaft 140 (the end received by the indent in the locking knob 115 and closest to the rear end of the device 100) to the wider length, from the wider length to the flange 210, and from the flange to the front end of the shaft (the end closest to the front end of the device 100 and distal from the locking knob 115).

The narrower length at the rear end of the shaft 140 is held entirely within the indent in the locking knob 115 and the wider length extends from the front end of the locking knob part way towards the front end of the shaft. The radius of the wider length of the shaft 140 is less than that of the narrower portion of the bore 220, such that when the locking knob 115 does not cover the holes 150, the balls 120 are able to be displaced partially into bore 220 such that the device 100 and the release housing 130 can adopt the unlocking configuration (shown in Figures 2A and 3B).

The flange 210 is circular and has a radius substantially equal to the wider portion of the bore 220, within which the flange is located. A helical spring 200 is arranged around the shaft 140 between the flange 210 and the face 230 at the rear end of the wider portion of the bore 220. The spring 200 biases the shaft 140 (and by extension the locking knob 115 attached to the rear end thereof) towards the front end of the device 100 and towards the locking configuration (shown in Figures 1, 2B and 3A).

A sealing ring 240 is provided on the face of the flange 210 facing towards the front end of the device 100. The sealing ring 240 being around the narrow length of the shaft 140 between the flange and the front end of the shaft 140. A head is provided at the front end of the shaft 140 to retain the sealing ring 240 against the flange 210.

The sealing ring provides a seal between the shaft 140 and the wall of the bore 220. Therefore, when exhaust from the attachment housing 400 causes the pressure inside the void 250 inside the bore 220 between the sealing ring 240 and the hammer housing 300 to increase, the shaft 140 will be forced towards the rear end of the device 100. This will force the release housing 130 from the locking configuration into the unlocking configuration.

An annular groove 180 is formed in the wider length of the shaft 140 with a depth substantially equal to the narrower lengths of the shaft. Radial spring-loaded pins 190 are displaceable into and out of the wall of the narrower section of the bore 220 between the face 230 and the shoulder defined between the tail section 135 and the main body section of the release housing 130.

The spring-loaded pins 190 are arranged to engage with the annular groove 180 in the wider length of the shaft 140 (when the shaft 140 and the locking knob 115 are displaced towards the rear end of the device 100 in the locking configuration), or to engage with the shoulder between the wider length of the shaft 140 and the narrower length of the shaft 140 between the wider length and the flange 210 (when the shaft and the locking knob 115 are displaced towards the front end of the device 100 in the unlocking configuration). The spring-loaded pins 190 thereby lock the device 100 and the release housing 130 in the locking or unlocking configuration.

The edges of the annular groove 180 and the shoulder between the wider length of in the shaft 140 and the narrower length of the shaft 140 are slanted such that when sufficient force is applied to the shaft 140 the locking pins 190 are displaced radially outwards and the shaft 140 is free to move.

The hammer housing 300, which interconnects the release housing 130 and the attachment housing 400 is arranged with its front end within the exhaust sleeve 600 of the attachment housing and its rear end within the bore 220 of the release housing.

The hammer housing 300 separates the front end of the release housing 130 and the rear end of the exhaust sleeve 600 such that a gap 620 is defined between the release housing 130 and the attachment housing 400. The width of the gap 620 varies in use as the hammer housing 300 slides lengthwise within the exhaust sleeve 600.

Hammer housing 300 is generally cylindrical and comprises three cylindrical sections of different radii: a narrowest rear section, a widest front section and an intermediate section.

The narrowest rear section is at the rear end of the hammer housing 300 and is located entirely within bore 220 of the release housing 130, between the front end of the bore 220 and the front end of the release shaft 140. This section has a radius smaller than that of the wider section of the bore 220 through the release housing 130 such that a void 250 for exhaust gasses is defined between the hammer housing 300 and the sealing ring 240 of the flange 210 of the release shaft 140.

The widest front section is at the front end of the hammer housing 300 and is located 30 within the forward wider portion of the bore of the exhaust sleeve 600. The exhaust sleeve 600 has a central bore with a wider front length of substantially equal radius to the widest section of the hammer housing 300 and a narrower rear length of substantially equal radius to the intermediate section of the hammer housing 300.

The widest front section of the hammer housing 300 is unable to slide past the shoulder defined between the wider front length and the narrower rear length of the bore of the exhaust sleeve 600, due to the shoulder 305 between the intermediate section and the widest front section of the hammer housing contacting the shoulder of the bore of the sleeve 600.

The intermediate section of the hammer housing 300, which is located intermediate the front widest section and the rear narrowest section is of equal radius to the narrower rear length of the bore of exhaust sleeve 600. The rear end of the intermediate section is located within the bore 220 of the release housing 130 and comprises a threaded portion which engages with a threaded portion on the interior of the front end of the bore 220. The intermediate section extends forwards from the front end of the release housing, across the variable width gap 620 between the release housing and the exhaust sleeve and through the narrower rear section of the bore of the exhaust sleeve 600 to the widest front section of the hammer housing 300.

A plurality of exhaust passages 325 extend through the hammer housing 300 from its front face to the shoulder between intermediate section and the narrowest rear section, thereby interconnecting the interior of the wider front section of the bore of the exhaust sleeve and the void 250 in the bore of the release housing 130.

The hammer housing comprises a front cylindrical bore extending lengthways from its front end, through its forward widest section and part way through its intermediate section. This front cylindrical bore contains a firing pin 390 and a push rod 380 and the firing pin spring 345. The forward end of this forward bore is sealed by a threaded seat 320 for the firing pin 390, through which the firing pin 390 extends and is able to slide. The threaded seat 320 being screwed into a threaded foremost portion of this front cylindrical bore.

The hammer housing 300 further comprises a rear cylindrical bore extending lengthways from its rear end, through its rear narrowest section and part way through its intermediate section. This rear bore contains the hammer 330 and the hammer spring 340. The rear end of this rear bore is sealed and separated from the void 250 inside the bore of the release housing 130 by a threaded bung 310 which is screwed into a threaded rearmost portion of this rear cylindrical bore.

The front and rear cylindrical bores of the hammer housing 300 are interconnected by an aperture 360 between the rear end of the front bore and the front end of the rear bore. The aperture 360 comprises a front frustoconical portion 370 and a rear cylindrical portion and is coaxial with the front and rear bores.

The front bore of the hammer housing 300 contains a firing pin 390 which is held by and is slideable through the seat 320 at the front end of the bore, a push rod 380 behind the firing pin 390 which extends into and is slideable partially through the aperture 360, and a firing pin spring 345 which is arranged around a portion of the push rod 380 between the rear end of the bore and a flange 395 at the front end of the push rod 380.

The push rod consists of a flange 395 at its front end an elongate rod portion extending rearwards therefrom. The rod portion comprising a rear cylindrical rod portion with a radius smaller than the radius of the cylindrical portion of the aperture 360 and an front cylindrical rod portion with a radius substantially qual to the radius of the cylindrical portion of the aperture 360. A tapered generally frustoconical portion is provided between the front and rear cylindrical rod portions.

The firing pin spring 345 biases the push rod 380 and the firing pin 390 forwards, towards a forwards-most arrangement wherein the firing pin 390 extends forwards out of the front end of the bore but is prevented from further forward displacement by the seat 320. In the forwards most arrangement, the push rod 380 is arranged with its front flanged end 395 pressed against the rear end of the firing pin 390 by the firing pin spring 345 and with its rear end within the aperture 360. This forwards-most arrangement is shown in Figures 1, 2A, and 2B.

The rear bore of the hammer housing 300 contains a hammer 330 and a hammer spring 340 arranged between the hammer 330 and the bung 310 at the rear end of the rear bore. The hammer 330 is cylindrical and has a radius substantially equal to the radius of the rear bore, within which the hammer is slideable. The hammer spring 340 biases hammer forwards towards a forward-most arrangement wherein the front end of the hammer 330 is pressed against the front end of the rear bore. This forwards-most arrangement is shown in Figures 1, 2A, and 2B.

The hammer 330 comprises a cylindrical hole 350 in the centre of its front end. The cylindrical hole has a radius less than that of the cylindrical rear portion of the aperture 360 (such that a lip is defined around the edge of the hole 350 at the rear end of the aperture when the hammer 330 is pressed against it) and greater than that of the rear end of the push rod 380. The depth of the hole 350 being shallow enough for the rear end of the push rod 380 to be displaced into contact with the base at the rear of the hole 350 In use, the hammer spring 340 and the firing pin spring 345 bias the hammer 330, the push rod 380 and the firing pin 390 towards their forwards-most positions and these components will be held in these positions unless the front end of the firing pin 390 is depressed rearwards.

When the firing pin 390 is displaced rearwards, the firing pin spring 345 is compressed and the push rod 380 is depressed rearwards. As the firing pin 390 continues to be depressed rearwards, the rear end of the push rod 380 contacts the lip around the hole 350 in the hammer 330 (due to the rear end of the push rod 380 being narrower than the aperture 360 such that gravity causes the rear end of the push rod 380 to unaligned with the central axis of the hammer housing 300 and the bores thereof) and the hammer 330 is also pushed rearwards. This continues until the tapered portion of the push rod 380 contacts the frustoconical portion 370 of the aperture 360, which displaces the rod portion of the push rod 380 towards the central axis of the hammer housing 380. This causes the rear end of the push rod 380 to slip into the hole 350 in the front end of the hammer 330, which in turn causes the hammer 330 to displaced rapidly forwards by the hammer spring 340 until the base at the rear of the hole 350 hits the end of the push rod 380 thereby imparting a force to the push rod 380 and the firing pin 390 in contact therewith. The process of rearwards depression of the firing pin 390 is shown sequentially in Figures 2A, 3A and 3B.

The exhaust sleeve 600 comprises an annular seal 610 supported in an annular groove around the wall of its narrower bore portion. The annular seal 610 creates a seal between the exhaust sleeve 600 and the intermediate section of the hammer housing 300, thereby ensuring any exhaust from the detonation of a cartridge 590 in the attachment housing 350 by the firing pin 390 which enters the bore of the exhaust sleeve 600 between the back of the barrel housing 500 and the front of the hammer housing 350 is only able to escape through the exhaust passages 325 into the void 250 in the bore 220 of the release housing. Such exhaust will therefore press the sealing ring 240 and the release shaft 140 backwards and switch the release housing 300 from its locking configuration to its unlocking configuration.

The barrel housing 500 is a cylindrical housing of substantially equal thickness to the exhaust sleeve 600 and the main body portion of the release housing 130. The barrel housing 500 comprises a female threaded recess at its rear end for engaging with a male threaded portion at the front end of the exhaust sleeve 600 to define a watertight seal 410 between the exhaust sleeve 600 and the barrel housing 500. These threaded portions may be unscrewed so as to separate the exhaust sleeve 600 and the barrel housing 500, such as when loading a cartridge 590 as shown in Figure 2A.

The barrel housing 500 comprises a nail 520 for driving into a target 700 so as to attach the device 100 to the target. The barrel housing 500 further comprises a central barrel 510 from which the nail 520 is fired, a piston 540 for holding the head of the nail and for driving it out of the barrel 510 when fired and a nail guide 530 within the barrel 510 for guiding the nail 520 when it is fired. The barrel housing 500 receives a cartridge 590 which drives the piston 540 and the nail 520 down the barrel when it is detonated by the firing pin.

The barrel housing 500 further comprises an expansion chamber 570 surrounding the barrel and a blast plate 560 separating the expansion chamber 570 from the bore of the exhaust sleeve 600 in use.

The front face 630 of the barrel housing is a solid wall with a thin point at its centre through which the nail 520 is driven in use. The barrel 510 extends from the threaded recess at the rear of the barrel housing 500 to a point adjacent front face 630. The barrel 510 comprises an elongate bore coaxial with the cylindrical barrel housing 500 which extends along the full length of the barrel 510. The bore comprises a short narrow rear cylindrical portion which is open to the threaded recess and which receives a pyrotechnic cartridge 590 in use, and a longer wider cylindrical portion which extends from the location of the cartridge 590 to the front face 630 through which the nail 520 is punched in use.

A generally cylindrical piston 540 of the same radius as the wider cylindrical portion of the barrel bore is located within and slideable along the wider cylindrical portion of the barrel bore. The piston has a generally hemi-spherical indent in its rear face for capturing the blast from the detonation of a cartridge 590 in the narrow portion of the barrel bore.

The head of the nail 520 is held within the piston 540 such that when the piston 540 is slid along the barrel the nail 520 is as well. The piston 540 holds the head of the nail 520 such that is not displaceable out of the barrel 510 and that after it has been driven into a target 700, the device 100 will be nailed to the target 700.

A cylindrical disk-shaped nail guide 530 with a radius equal to the wider portion of the barrel bore and a central aperture through which the nail extends is also located within the bore of the barrel 510. The nail guide holds an intermediate portion of the nail 520 in the centre of the bore such that the nail 520 is held substantially centrally within and coaxially to the barrel 510 and the barrel housing 500. The nail guide 530 is arranged to slide along the wider portion of the barrel bore to the end face 630 of the barrel guide such that the nail 520 is maintained central within and coaxial to the barrel 510 as it is driven into the target.

An expansion chamber 570 in the shape of an annular cylinder is located around the barrel, the expansion chamber being separated from the threaded recess at the rear of the barrel housing 500 by a blast plate 550 through which a plurality of blast holes 550 are formed.

An exhaust vent 580 is formed through the barrel between the wider portion of the bore of the barrel 510 and the expansion chamber 570. The exhaust vent 580 being located towards the front of the barrel such that the exhaust vent is only partially behind the piston 540 when the piston 540 has been displaced to its most forward position (in which the nail 520 has penetrated the front face 630, and the disk guide is pressed against the front face of the barrel 510 by the piston 540, as shown in Figure 3B).

In use, when the cartridge 590 is detonated by an impact from the firing pin 390, the rapidly expanding gas it produces will drive the piston 540 forwards down the barrel 510 such that the nail 520 is driven through the centre of the front face 630 of the attachment housing. The piston 540 is driven until it presses the nail guide 530 against the front end of the barrel bore, at which point the exhaust vent 580 will be behind the piston, allowing the expanding gas to enter the expansion chamber 570. The gas passes from the expansion chamber 570, through the holes 560 in the blast plate 550, into the gap between the barrel housing 500 and the hammer housing 300, inside the wider front portion of the bore of the exhaust sleeve 600. The gas then passes through the exhaust passages 325 in the barrel housing 300 into the void 250 inside the bore 220 of the release housing, where the increase in pressure presses the seal 240 and the release shaft 140 rearwards, switching the release housing form its locking configuration to its unlocking configuration.

The device 100 is typically used in a generally or substantially horizontal orientation, as shown in Figures 2A to 3B.

Figure 2A shows a sectional view of the device 100 being prepared for loading into a socket 110 on a deployment system. The barrel housing 500 has been unscrewed from the exhaust sleeve 600 to allow a cartridge 590 to be inserted into the barrel 510 and the locking knob 115 has been pulled rearwards such that the release housing 130 is in its unlocking configuration with the locking balls 120 not protruding from the tail section 135 and with the release spring 200 compressed. The release housing 130 is held within the locking configuration by the spring-loaded pins 190 which contact the shoulder between the wider and intermediate narrower portions of the release shaft 140.

Figure 2B shows a sectional view of the device 100 when the barrel housing 500 is subsequently screwed onto the exhaust housing 600 creating a watertight seal 410.

The tail section 135 of the release housing 130 is inserted into a socket 110 on a carrier frame 170 and the locking knob 115 is pressed forwards, pushing the release shaft past the spring-loaded pins 190 such that the release housing enters its locking configuration. In the locking configuration, the spring-loaded pins engage with the groove 180 in the wider portion of the release shaft 140 and the balls 120 are forced outwards by the locking knob such that they engage with the groove 160 in the interior of the socket 110.

As no pressure is applied to the front end 630 of the device 100, the firing pin spring 345 biases the firing pin 390 forwards from the hammer housing 300, such that a gap is maintained between the hammer housing 300 and the rear of the barrel housing 500 within the bore of the exhaust housing 600. As such a gap 620 is maintained between the exhaust housing 600 and the release housing 130.

The attachment housing 400 (consisting of the barrel housing 500 and the exhaust sleeve 600) is able to slide lengthways backwards with respect to the release housing 130 and the hammer housing 300, but in doing so displaces the firing pin 390 backwards.

The device 100 is therefore ready to be fired. A clip or other safety device may be inserted into the gap 620 between the exhaust sleeve and the release housing 130 to prevent eh attachment housing 400 being slid backwards and thereby prevent the device from being accidentally fired.

Figure 3A shows a sectional view of the device 100 being pressed against a target 700 shortly before the pressure causes the device 100 to be fired. The front face of the barrel housing 500 is pressed against the target 700, thereby forcing the attachment housing 400 backwards. This backwards movement compresses the gap 620 and the space between the barrel housing 500 and the hammer housing 300, thereby pressing the firing pin 390 and the push rod 380 backwards and compressing the firing pin spring 345. The push rod 380 is not coaxial with the device 100 and the hammer housing and therefore its rear end is contacting the front face of the hammer 300 adjacent the central hole 350. However, the tapered portion of the push rod has contacted the frustoconical portion 370 of the aperture 360 and any further backwards movement of the attachment housing 400 will displace the push rod 380 towards the central axis of the device 100 such that its rear end enters the hole 350 in the hammer 330.

Figure 3B shows a sectional view of the device 100 after it has been fired by pressing it further against the target 700. The further backwards movement of the attachment housing 400 has displaced the push rod 380 towards the central axis of the device 100 such that its rear end has entered the hole 350 in the hammer 330. The hammer 330 has therefore been pushed forwards rapidly by the compressed hammer spring 340 until the base of the hole 350 impacted the end of the push rod 380. This in turn has caused the push rod 380 to impact the firing pin 390, which in turn has impacted the cartridge 590, causing it to detonate.

Detonation of the cartridge 590 has caused rapidly expanding gasses to force the piston 540 forwards down the barrel 510, thereby forcing the nail 520 down the barrel, through the front end face 630 of the device 100 and into the target 700. The head of the nail 520 has been retained within the piston in the barrel 510, thereby nailing the device 100 to the target 700.

The rapidly expanding gasses have passed through the exhaust vent 580, the expansion chamber 570, the holes 560 through the blast plate 550, the gap between the barrel housing 500 and the hammer housing 300, the exhaust passages 325 through the hammer housing 300, and into the void 250 inside the bore 220 of the release housing 130. Here the gasses have been prevented from further escape by the sealing ring 240 on the flange 210 of the release shaft 140.

The increased pressure in the void 250 as a consequence of these gasses has forced the release shaft 140 backwards past the spring-loaded pins 190, thereby forcing the locking knob 115 backwards and allowing the balls 120 to fit into the holes 150 and the bore 220 such that they do not protrude from the tail section 135 of the release housing 130. The release housing has therefore been actuated into its unlocking configuration, allowing the device 100 to exit the socket 110 which is securely fixed to the holding frame 170.

In the event that the cartridge 590 does not detonate, the device 100 may be moved backwards away from the target 700. The firing pin spring 345 will press the push rod 380 and the firing pin 390 forwards against the back of the barrel housing 500, thereby displacing the attachment housing 400 forwards and resetting the device 100 allowing for another attempt to initiate the cartridge 590.

Figure 4A shows an overall view of a device 100 as described above with a payload 720 attached thereto. The payload 720 is contained within a cylindrical housing of substantially equal radius to the device 100. The payload 720 is connected to the device 100 by a payload connector 730, which comprises two cylindrical slots for the insertion of the device 100 and the payload 720.

The payload connector 730 is of equal length to the main body section of the release housing 130 around which it fits, leaving the tail section 135 and the gap 620 unobstructed.

The payload connector may be constructed from any lightweight material, such as from aluminium, but is preferably constructed from a polymer material with a density similar to that of water; for example, high density polyethylene.

The illustrated payload 720 contains an acoustic pinger 740, a device which emits acoustic pulses for receipt by a receiving unit. Alternative payloads may contain a suitable releasable radio frequency (RF) buoy 770, a spoofing device 780 for mimicking or masking the parameters of a vessel, or a disarming or disabling charge.

Figure 4B shows an overall view of a pair of twin carrier frames 710, each supporting four sockets 110. Each socket 110 contains a device 100 with a payload 720 as described above with reference to Figure 4A, such that four devices 100 extend from each of two opposite sides of the frames 710.

The frames 710 are parallelogram shaped, such that each device 100 extends a different distance from the other devices 100 extending from the same side. This allows the devices to be attached to targets 700 one by one without risking accidental firing or attachment of the other devices.

The number of devices 100 which may be supported by a carrier fame is only limited by the size of the remotely operated vehicle (ROV) carrying the frame.

The holding frames may be constructed from virtually any lightweight material, for example, the frames may be constructed from an aluminium alloy. Preferably, the frames are constructed from a polymer material with a density similar to that of water, such as high-density polyethylene.

Figure 5A shows a plan view of the frames 710 shown in Figure 4B within a skid 750 of an ROV 760. One of the devices 100 is shown removed from its socket 110.

Figure 5B shows overall views of the skid 750 and the remainder of a cuboid ROV for carrying the skid 750 and the devices 100.

Most cuboid ROV's have the capability in their operating software to operate as if the rear of the ROV is the front of the ROV. Such a reversal may be performed after all the devices on one side of the ROV have been deployed.

Figure 6 shows an ROV 760 in use and a number of different example deployed devices 100. A device 100 with an acoustic pinger 740 as its payload 720 has been attached a sea mine 745 on the sea floor, a device with a spoofing device 780 as its payload 720 has been attached to a marine vessel 785, and a device with deployable RE buoy 770 as its payload 720 has been attached to an undersea object or structure.

The invention has been described by way of example only and it will be appreciated 10 that variation may be maid to the described embodiments without departing from the scope of the invention as defined by the claims.

Reference Numerals Device for attaching to a target Socket Locking knob s 120 Locking ball Release housing Tail section of release housing Release shaft Holes through tail section wall 160 Groove in socket Frame of ROV Groove on wider length of release shaft Spring-loaded pins Release spring 210 Flange of release shaft 220 Bore through release housing 230 Face between wider and narrower portions of release housing bore 240 Sealing ring of release shaft flange 250 Void within release housing bore 300 Hammer housing 305 Shoulder between front and intermediate sections of the hammer housing 310 Threaded bung sealing rear bore of hammer housing 320 Seat for the firing pin 325 Exhaust passages 330 Hammer 340 Hammer spring 345 Firing pin spring 350 Hole in centre of the front face of the hammer s 360 Aperture between front and rear bores of hammer housing 370 Frustoconical portion of the hammer housing aperture 380 Push rod 390 Firing pin 395 Flange of the push rod 400 Attachment housing 410 Watertight seal between the barrel housing and exhaust sleeve 500 Barrel housing 510 Barrel 520 Nail 530 Nail guide 540 Piston 550 Blast plate 560 Holes in blast plate 570 Expansion chamber 580 Exhaust vent hole 590 Pyrotechnic cartridge 600 Exhaust sleeve 610 Annular seal of exhaust sleeve 620 Variable gap between exhaust sleeve and release housing 630 Front face of attachment housing 700 Target 710 Frame 720 Payload 730 Payload connector 740 Acoustic pinger 745 Sea Mine 750 Skid of remotely operated vehicle 760 Remotely operated vehicle (ROV) 770 Deployable radio frequency buoy 780 Spoofing device 785 Marine vessel 790 Undersea structure or object

Claims

Claims 1 A device for attaching to a target, the device comprising: an attachment means for attaching to a target and a releasable connection means for connecting the device to a carrier, wherein the connection means is automatically released after the attachment means attaches to a target.
2 A device according to claim 1 wherein the target is an underwater item of unexploded ordnance or a marine vessel.
3 A device according to claim 1 or claim 2 wherein the attachment means is at a first end of the device and the releasable connection means is at a second end of the device opposite the first end.
4 A device according to any preceding claim wherein the attachment means is for driving a nail partially into the target.
A device according to claim 4 wherein the attachment means retains the head of the nail within the device.
6 A device according to claim 4 or claim 5 wherein the attachment means is for driving the nail through a wall of the device into the target in use.
7 A device according to any of claims 4 to 6 wherein the attachment means drives the nail away from the releasable connection means in use.
8 A device according to any of claims 4 to 7 wherein the nail is driven into the target in use by the detonation of an explosive charge.
9 A device according to claim 8 wherein the explosive charge is a cartridge received by the device.
10.A device according to claim 9 wherein the connection means is actuated to release by expanding gasses from the detonation of the explosive charge and the expanding gasses are blocked from reaching and actuating the connection means until after the device has been into the target in use.
11.A device according to any of claims 8 to 10 wherein the attachment means comprises a barrel and a piston located within and is slideable along the barrel.
12.A device according to claim 11 wherein the piston is connected to or defines the head of the nail.
13.A device according to claim 11 or claim 12 wherein the piston defines a barrier across substantially the entire cross section of the barrel past which expanding gasses are unable to pass.
14.A device according any of claims 11 to 13 wherein the attachment means further comprises a nail guide which fits around the shaft of the nail and aligns the shaft with a central axis of the barrel.
15.A device according to any of claims 11 to 14 wherein the attachment means comprises one or more exhaust vents through side walls of the barrel through which expanding gasses driving the piston along the barrel are able to exit after the piston has passed the exhaust vents.
16.A device according to any preceding claim wherein the attachment means is displaceable with respect to the connection means and the attachment means is actuated to attach to the target by displacing the attachment weans with respect to the connection means.
17.A device according to claim 16 wherein the attachment means is actuated by displacing it towards the connection means.
18.A device according to claim 16 or claim 17 comprising a means biasing the attachment means away from the connection means.
19.A device according to any of claims 16 to 18 comprising a hammer and a firing pin, the hammer being arranged to be driven to impact the firing pin when the attachment means is displaced to a threshold with respect to connection means.
20.A device according to claim 19 wherein firing pin is displaced with the attachment means, the hammer is biased towards the firing pin and a separation means maintains a minimum separation between the hammer and the firing pin until the attachment means is displaced to the threshold.
21.A device according to any preceding claim wherein the releasable connection means is for at least partially retaining the device within a socket.
22.A device according to claim 21 wherein the releasable connection means comprises one or more retractable projections for engaging with one or more indents or recess on the interior of the socket.
23.A system comprising: a carrier and one or more of devices according to any of claims 1 to 26; the one or more devices being releasably connectable to the carrier with their releasable connection means.
24.A system according to claim 23 wherein the one or more devices are a plurality of devices.
25.A system according to claim 23 or claim 24 wherein the carrier is or is comprised by a remotely operated underwater vehicle.