Abstract:
The invention features utilization of a duplicate form for creating a conformal cavity which equally mates with an original form having the same shape as the duplicate form. The duplicate form is situated in the wall from the inside of the wall, elastomer is cured onto the outside of wall and around the duplicate form, the duplicate form is removed, and the original form is situated in place of the duplicate form. The shape of the hole in the wall is not in strict conformity with the shape of the duplicate form and the original form, but rather is characterized by a small aberration which leaves a space when either the duplicate form or the original form is situated in the hole. This small aberration, together with the elastomeric quality of the cured material, permits ingressive venting during removal of the duplicate form and egressive venting during insertion of the original form. In typical inventive practice, the manipulative steps are performed from the inside of the wall. Facilely and expeditiously, the invention achieves tight installation of the original form.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to methods, systems and apparatuses for effecting installation of devices, more particularly for installing instruments such as sensors in elastomerically coated structures such as submarine hulls. 
     The U.S. Navy implements electronic sensors which are situated in elastomer-coated submarine hulls. 
     According to a method conventionally used by the U.S. Navy for installing an electronic sensor in an elastomer-coated submarine hull, the elastomer is cast around the sensor, which is situated at the outside of the hull. This old method proves successful, and provides minimal or no gap between the sensor and the surrounding elastomer. However, this method is time consuming. Moreover, removal of the sensor requires cutting and/or grinding of the elastomeric material around the sensor, while working from the exterior of the submarine. Furthermore, the process of cutting and/or grinding may damage the sensor. 
     Another technique commonly used by the U.S. Navy is to cast the elastomer on the outside of the hull, and to cut a hole in the elastomer, thereby permitting the sensor to be installed from the exterior of the submarine. This method allows for easy installation and removal of the sensor. However, this method as well is time consuming. In addition, this method does not necessarily provide minimal or no gap between the sensor and the elastomer. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an efficient and effective method for installing a sensor in an elastomer-coated submarine hull. 
     A notable realm of inventive application is that involving submarines. According to many such inventive embodiments, a device (e.g., an electronic sensor) is inventively rendered removably installed in a cured elastomer-coated submarine hull. Inventively utilized is a plug (preferably a structurally solid plug) having a three-dimensional geometrical shape which is identical to that of the device to be installed. 
     Typical embodiments of the inventive methodology generally include the following steps or stages: 
     I. An opening in a hull (or other wall-like structure) is (or has been) produced, such hull opening having a shape which comports with that of the plug, except for a relatively small peripheral hole which will permit insertion of a tube adjacent the plug once the plug is installed in the hull opening. 
     II. A solid plug is (or has been) produced, such solid plug having the same geometrical shape as that of the to-be-installed device. 
     III. The plug is coated with a mold release agent, for many inventive embodiments preferably a water soluble mold release agent such as polyvinyl alcohol (PVA). 
     IV. The practitioner working from the inside of the hull, the plug is installed in the hull opening prior to casting the elastomer to the hull. Such installation is accomplished whereby the plug is even or flush, or substantially so, with respect to the hull opening, except for the small peripheral hole. 
     V. The elastomer (e.g., viscoelastic material) is cast and cured with respect to the outside of the hull. What was previously a bare structural hull has now become an externally cured-elastomer-coated hull. 
     VI. After the elastomer has been cast and cured, a small diameter venting tube (e.g., a tube made of metal) is inserted by the practitioner(s) (who is/are working from the inside of the hull). It is preferable inventive practice for many inventive embodiments that the venting tube be lubricated (with a lubricating agent such as that used for lubricating the device as described in step VIII hereinbelow) prior to insertion. While inserted, the venting tube proceeds first through the peripheral hole, and then between the plug and the elastomer. 
     VII. Many inventive embodiments preferably use a mold release agent which is liquid (e.g., water) soluble. While the venting tube is in place, pressurized liquid (e.g., water) is fed through the venting tube so as to flow between the elastomer and the plug, thereby dissolving the liquid (e.g. water) soluble mold release agent. The plug is removed by the practitioner(s) (who is/are working from the inside of the hull) by being slidably withdrawn from the cured elastomer-coated hull. Such removal is facilitated by the mold release agent which coats the plug, and by the venting tube which allows air to vent into the resultant increasing void in the elastomer as the plug is being removed. Complete removal of the plug leaves a cavity which will conformally serve as a sort of chamber or compartment for snugly holding the device. The cavity comprises the hull opening and the maximally voluminous elastomer void (i.e., the entirely unoccupied space in the elastomer). 
     VIII. The device is coated with a lubricating agent. 
     IX. A venting tube (such as that used for plug removal) is inserted through the peripheral hole by the practitioner (who is working from the inside of the hull). 
     X. The cavity (which comprises the hull opening and the maximally voluminous elastomer void) has a shape which comports with that of the device. While the venting tube is in place, the lubricant-coated device is installed by the practitioner(s) (who is/are working from the inside of the hull) by being slidably advanced into the aperture. Such installation is facilitated by the lubricating agent which coats the device, and by the venting tube which allows air to vent from the resultant decreasing void in the elastomer as the device is being installed. 
     Once inventively installed, there is little or no gap between the device and the surrounding elastomer. 
     Moreover, the device can be easily removed from the interior of the submarine or other edifice. A venting tube (such as that used for plug removal or device installation) is inserted by the practitioner(s) (who is/are working from the inside of the hull) first through the peripheral hole, and then between the device and the elastomer. Again, it is preferable inventive practice for many inventive embodiments that the venting tube be lubricated (with a lubricating agent such as that used for lubricating the device as described in step VIII hereinabove) prior to insertion. Removal of the device is facilitated by the remaining lubricating agent which coats the device, and by the venting tube which allows air to vent into the resultant increasing void in the elastomer as the device is being removed. 
     The present invention features implementation of a plug which is constructed to be geometrically identical to a device intended to be installed. The present invention also features the provision of a cavity or chamber which defines a shape identical to that of the device as well as that of the plug. 
     The hull opening having been formed in conformity with the plug or the device, and the elastomeric material having been molded and cured in conformity with the plug, the device will fit inside the chamber-like cavity as well (i.e., as flushly or evenly) as does the plug when the plug is removed and the device is installed in place of the plug. Therefore, an important inventive advantage is that when the device is completely installed, little or no gap exists between the device and the surrounding elastomer. 
     The plug serves as a sort of temporary, precursive geometric form which is used to establish the shape of the cavity which will enclose the enduring, permanent geometric form, viz., the device. The plug is made to be an exact geometric duplicate of the device. The ordinarily skilled artisan is familiar with the various methodologies, such as involving molding techniques, for fabricating a plug which is an identical geometric copy of an original device or other object. 
     The plug and the device both fit the same conformal cavity, but are not necessarily identical in all geometric respects. The geometric sameness/congruency of the plug and device is inventively crucial at least with respect to the respective portions of the plug and device which are inside the chamber-like cavity when the plug or the device is in the completely installed position. 
     Another inventive feature is the elastomeric nature of the material layer which covers the hull or other structural wall. Since the hull coating is elastomeric, this beneficially allows for the insertion of the venting tube without removal of any elastomeric material. 
     It is customary for the United States Navy to cast and cure elastomer onto submarine hulls. The ordinarily skilled artisan is familiar with the conventional methodologies and techniques pertaining to such practices. 
     A type of substance known as a “mold release agent” is inventively used to prevent bonding of the elastomer to the plug. Thus facilitated is movement of the plug relative to the elastomer&#39;s cavity, within which the plug is retracted subsequent to cure of the elastomer. For instance, some inventive embodiments may preferably utilize, on the exterior surface of the plug, a polymer or polymer-containing material having elastomeric mold release properties; such mold release agents may be particularly well suited for effecting “mold release” of the plug from the surrounding elastomer. 
     There are two general categories of mold release agents, viz., “external” mold release agents and “internal” mold release agents. External mold release agents are directly applied to the mold, whereas internal mold release agents are directly added into the molding composition. In conventional practice using an external mold release agent, the release agent is typically used to coat a mold cavity in order to prevent sticking of the molded piece to the mold cavity when the molded piece is removed from the mold cavity. 
     Typical embodiments of the present invention will preferably implement “external” mold release agency. Before the plug is inserted in the hull opening, the plug is coated with an external mold release agent; preferably, the externally applied mold release agent has mold release properties vis-a-vis&#39; the elastomer anticipated to surround the plug. 
     However, some inventive embodiments can implement “internal” mold release agency, whereby the plug is fabricated so as to include a substance or substances having mold release properties, preferably vis-a-vis&#39; the elastomer anticipated to surround the plug. 
     The ordinarily skilled artisan is familiar with a variety of natural compounds, synthetic compounds and inorganic substances which are known to effectuate “mold release.” Known mold release agents (also known as “release agents” or “parting agents”) include waxes, soaps, silicones (e.g., silicone oil, silicone oxide powder, etc.), mineral oils, powders (e.g., talc, mica, etc.), aliphatic acid derivatives, glycols and other polymeric or polymer-containing compounds. Certain mold release agents, such as polyvinyl alcohol (PVA), are known to be especially effective in applications involving elastomers and elastomeric surfaces. 
     In the light of this disclosure, the ordinarily skilled artisan should be capable of practicing mold release of the plug in relation to the chamber-like cavity&#39;s hull opening and elastomer void. The following United States patents, hereby incorporated herein by reference, are merely exemplary among the plethora of United States patents pertaining to mold release agents: Jackson U.S. Pat. No. 3,935,291 issued Jan. 27, 1976; Castro et al. U.S. Pat. No. 4,101,976 issued Jul. 18, 1978; Boehmke et al. U.S. Pat. No. 4,110,119 issued Aug. 29, 1978; Horiuchi et al. U.S. Pat. No. 4,308,063 issued Dec. 29, 1981; Newkirk et al. U.S. Pat. No. 4,371,476 issued Feb. 1, 1983; Nakai U.S. Pat. No. 5,409,979 issued Apr. 25, 1995; Schur U.S. Pat. No. 4,740,324 issued Apr. 26, 1988; Franke et al. U.S. Pat. No. 4,889,908 issued Dec. 26, 1989; Piskoti U.S. Pat. No. 4,798,445 issued Jan. 10, 1989; Makus U.S. Pat. No. 4,925,882 issued May 15, 1990; Hanano U.S. Pat. No. 5,039,435 issued Aug. 13, 1991; Wagner U.S. Pat. No. 5,618,336 issued Apr. 8, 1997; Jennings et al. U.S. Pat. No. 5,883,166 issued Jun. 26, 1997; Yamana et al. U.S. Pat. No. 5,804,674 issued Sep. 8, 1998; Froeschmann U.S. Pat. No. 5,872,085 issued Feb. 16, 1999. 
     A further inventive feature is utilization of the venting tube, which allows the void in front of either the plug or the sensor to be ventilated or vented, thereby propitiously avoiding either a vacuum (upon withdrawal out of the void) or pressurized air (upon advancement into the void) to form in the void. 
     The inventive methodology allows the device to be both installed and removed in a quick, easy and inexpensive manner. In particular, the practitioner or practitioners can perform the inventive manipulative steps while being stationed on an interior deck or floor of the submarine or other edifice. 
     Moreover, this invention minimizes or eliminates risk of damage to the device during installation and removal. The harmoniousness which characterizes the inventive configuration promotes damage-free manipulation of the device. 
     The plug and the device each fit closely in the cavity. In this regard, some type of facilitative surface coating can be applied not only to the plug but also to the device. Utilization of a lubricating agent on the device, applied thereto prior to installation, is preferred for many inventive embodiments. The lubricating agent is used to promote movement of the device relative to the chamber-like cavity, within which the device is advanced during insertion and retracted during removal. 
     The ordinarily skilled artisan is familiar with a variety of lubricative substances (e.g., various lubricating oils) which are conventionally used to reduce friction between objects or parts in relative motion. In inventive practice, the lubricant eases installation of the device into the surrounding elastomer. The lubricant can also serve to ease deinstallation of the device from the surrounding elastomer. In the light of this disclosure, the ordinarily skilled artisan should be capable of practicing lubricatively facilitated movement of the device in relation to the cavity&#39;s hull opening and elastomer void. 
     Other objects, advantages and features of this invention will become apparent from the following detailed description of the invention when considered with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the present invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein like numbers indicate the same or similar components, and wherein: 
     FIG. 1 is a diagrammatic elevational view of a portion of a submarine hull wherein is inventively provided, in a submarine hull, a substantially round hole which includes a slot. 
     FIG. 2 is a diagrammatic elevational view of a portion of a submarine hull wherein is inventively provided, in a submarine hull, a substantially square hole which includes a slot. 
     FIG. 3 is a diagrammatic elevational view of a portion of a submarine hull wherein is inventively provided, in a submarine hull, a hole which includes a slot and is characterized by asymmetry, rectilinearity and curvilinearity. 
     FIG. 4 is the view of FIG. 1 illustrating accommodation by the substantially round hole of an agreeably shaped plug or device. 
     FIG. 5 the view of FIG. 2 illustrating accommodation by the substantially square hole of an agreeably shaped plug or device. 
     FIG. 6 the view of FIG. 3 illustrating accommodation by the irregularly shaped hole of an agreeably shaped plug or device. 
     FIG. 7 is a diagrammatic sectional plan view of an inventive embodiment wherein a section of the wall is shown to be provided with a hole which includes a slot. 
     FIG. 8 is view, similar to the view shown in FIG. 7, of an inventive embodiment wherein the plug is shown installed in place and encompassed by the cured elastomer. 
     FIG. 9 is a view, similar to the view shown in FIG.  7  and FIG. 8, of an inventive embodiment wherein the plug shown installed in FIG. 4 is shown being removed. 
     FIG. 10 is a view, similar to the views shown in FIG.  7  through FIG. 9, of an inventive embodiment wherein is shown (subsequent to removal of the plug as shown in FIG. 9) an empty chamber which was previously occupied by the plug. 
     FIG. 11 is a view, similar to the views shown in FIG.  7  through FIG. 10, of an inventive embodiment wherein the sensor is shown being installed in the chamber shown in FIG.  10 . 
     FIG. 12 is a view, similar to the views shown in FIG.  7  through FIG. 11, of an inventive embodiment wherein the sensor shown being installed in FIG. 11 is shown installed in place, encompassed by the cured elastomer. 
     FIG. 13 is a view, similar to the views shown in FIG.  7  through FIG. 12, of an inventive embodiment wherein the plug and its corresponding sensor are each identically characterized by a straight cylindrical shape, and are each identically provided with spiral threads for screw engagement with a hole in a submarine hull, the inside hole periphery having been complemetarily provided with spiral threads for such engagement. 
     FIG. 14 is a view, similar to the views shown in FIG.  7  through FIG. 13, of an inventive embodiment (similar to the inventive embodiment shown in FIG. 13) wherein the plug and its corresponding sensor are each identically characterized by a tapered cylindrical shape, and are each identically provided with spiral threads for screw engagement with a hole in a submarine hull, the inside hole periphery having been complemetarily provided with spiral threads for such engagement. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG.  1  through FIG. 3, hole  20  having slot  30  is produced in submarine hull  22 . With the notable exception of the deviation represented by slot  30 , hole  20  shown in FIG. 1 is cross-sectionally circular in shape, and hole  20  shown in FIG. 2 is cross-sectionally square in shape. Irregular, asymmetrical hole  20  shown in FIG. 3 cross-sectionally is partially curvilinear (e.g., elliptical) and partially rectilinear (e.g., polygonal) in shape. The two profiles shown in FIG.  1  and FIG. 2 are approximately regular, and in fact are approximately axially symmetrical. Hole  20  shown in FIG. 1 is substantially a circle, whereas hole  20  shown in FIG. 2 is substantially a type of regular polygon. 
     With reference to FIG.  4  through FIG. 6, the entity which occupies hole  20  can be conceived to be, in fully installed position, either plug  24  or sensor  48 . Since plug  24  and sensor  50  have the identical external geometric form, it is convenient to refer to the occupant of hole  20  as “plug/sensor  24 / 48 .” 
     Hole  20  and plug/sensor  24 / 48  shown in FIG.  1  and FIG. 4 each define the same circular outline or cylindrical figure. Hole  20  and plug/sensor  24 / 48  shown in FIG.  2  and FIG. 5 each define the same square outline or box figure. Hole  20  and plug/sensor  24 / 48  shown in FIG.  3  and FIG. 6 each define the same irregular figure or outline. 
     Hole  20  has a configuration which substantially agrees with the configuration of solid plug  24  as well as of sensor  48 . Major hole perimeter portion  26  comports with plug/sensor  24 / 48 . However, minor hole perimeter portion  28  provides slot  30  between plug/sensor  24 / 48  and hole  20 . The outside surface of plug/sensor  24 / 48  is even or flush with the inside surface of major hole perimeter portion  26 , but leaves a gap relative to the inside surface of minor hole perimeter portion  28 . 
     Plug  24  has the same three-dimensional geometrical shape as that of the to-be-installed sensor  48 . That is, solid plug  24  shown in FIG.  8  and FIG. 9 is a geometric duplicate of sensor  40  shown in FIG.  11  and FIG.  12 . As similarly shown in FIG. 1, FIG.  2  and FIG. 3, hole  20  is suitably shaped for plug  24 , and hence is suitably shaped for sensor  48 . Major hole perimeter portion  26  comports with plug/sensor  24 / 48 , whereas minor hole perimeter portion  28  provides slot  30  between plug/sensor  24 / 48  and hole  20 . 
     Inventive practice admits of a variety of cross-sectional shapes and sizes of hole  20  and its corresponding plug/sensor  24 / 48 . There are many possible polygonal cross-sectional shapes, other than the square shape shown in FIG.  2  and FIG. 5, for hole  20  and plug/sensor  24 / 48 , e.g., triangular, (non-square) rectangular, pentagonal, hexagonal, septagonal, octagonal, nonagonal, decagonal, etc. There are also many possible elliptical shapes other than the circular shape shown in FIG.  1  and FIG.  4 . There is also a diversity of possible hybridized rectilinear/curvilinear shapes other than that which is shown in FIG.  3  and FIG.  6 . The contours of hole  20  and plug/sensor  24 / 48  are certainly not required by this invention to be either regular or axially symmetrical. 
     In accordance with the present invention, hole  20  and its corresponding plug  24  and sensor  48  can each have any cross-sectional shape, regular or irregular, which permits inventive practice. In fact, the cross-sectional shape of hole  20  and plug/sensor  24 / 48  can have any combination of indicia of curvilinearity and/or rectilinearity, so long as inventive practice is permitted thereby. 
     Generally, in inventive practice, slot  30  admits of a variety of two-dimensional and three-dimensional shapes and sizes, and a variety of locations with respect to hole  20 . Slot  30 , located at the perimeter of hole  20 , can be located at any perimetric location on hole  20  which is reasonable accessible to the inventive practitioner and which coheres with the overall configuration of the inventive plug assembly. A related consideration is that slot  30  should be cross-sectionally sized as small as possible while enabling the facile insertion therethrough of a tubular device for properly effectuating venting according to this invention. 
     FIG.  7  through FIG. 12 sequentially illustrate the inventive methodology. 
     Reference now being made to FIG. 7, hull  22  has front hull surface  32 , back hull surface  34 , and hole  20  which includes slot  30 . Hull surfaces  32  and  34  are approximately vertical and are designated “front” (anterior) and “back” (rear or posterior), respectively, based on the perspective of the inventive practitioner. 
     Referring to FIG. 8, for many inventive embodiments, coupled with plug  24  is a removable, collar-like retaining plate  35  which includes a stopper-like projection  37 . The conformance of projection  37  with respect to slot  30  is perhaps best illustrated in FIG. 9, wherein projection  37  is shown separated from slot  30 . Projection  37  has approximately the same three-dimensional geometric shape as has slot  30 . In this regard, projection  37  and slot  30  are characterized not only by approximately the same cross-sectional shape but also by approximately the same length. Projection  37  serves to prevent uncured elastomer from entering slot  30 . 
     The exterior surface of solid plug  24  is coated with mold release agent  33 . At front hull surface  32 , plug  24  is inserted in hole  20 . 
     In typical inventive embodiments wherein a retaining plate  35  is implemented, retaining plate  35  is applied to plug  24  (to help keep it set) prior to casting and curing elastomer  38  with respect to back hull surface  34 . Many such inventive embodiments provide for engagement of retaining plate  35  with plug  24  prior to insertion of plug  24  in hole  20 ; some such inventive embodiments, however, provide for engagement of retaining plate  35  with plug  24  subsequent to insertion of plug  24  in hole  20 . 
     When in the fully inserted position, as shown in FIG. 8, plug  24  has protrusive plug portion  36  which extends aft of back hull surface  34 . Removable retaining plate  35  affixes plug  24  to submarine hull  22  at front hull surface  32 . Slot  30  is available in hull  22  for receiving the venting tube  40 . 
     Subsequent to complete insertion of plug  24  in hole  20 , castable elastomer hull coating  38  is cast onto back hull surface  34  so as to envelop protrusive plug portion  36 . The cast elastomer hull coating  38  is cured. Previously uncovered, structural hull  22  is now layered with elastomer  38 . 
     With reference to FIG. 9, after elastomer hull coating  38  is cured, retaining plate  35  is removed to permit installation of venting tube  40 . A small diameter metal venting tube  40  is lubricated (with a lubricating agent such as lubricant  50 ) to allow ease of insertion. Then, the venting tube  40  is inserted. Venting tube  40  is caused to enter slot  30  at front hull surface  32 . Venting tube  40  is advanced into and through slot  30 , and continued to be advanced by slipping between plug  24  and the deforming adjacent elastomer  38 . Venting tube  40  is moved in the backward or rearward direction (away from the practitioner), approximately in the direction indicated by arrow b in FIG. 11, as far back as necessary to effectuate venting during removal of plug  24 . 
     Protrusive venting tube portion  42  is the portion of venting tube  40  which extends behind back hull surface  34 . Generally, protrusive venting tube portion  42  will extend behind back hull surface  34  approximately as far as extends protrusive plug portion  36 . 
     Many inventive embodiments preferable utilize, for coating plug  24 , a mold release agent  33  which is soluble by a liquid such as water. A rinsing tube  59  (preferably flexible, e.g., made of plastic), such as shown in FIG.  8  and FIG. 9, is used for washing or flushing away the mold release agent  33 . In inventive practice generally, the rinsing via rinsing tube  59  should precede the venting via venting tube  40 . 
     Rinsing tube  59  is detachably attached to venting tube  40  (at the venting tube  40  end which is in front of front hull surface  32 ) by means of a retaining collar  60 . Depending on the inventive embodiment, this connection of venting tube  40  with rinsing tube  59  can be effected either prior to or subsequent to fully extended placement of venting tube  40  through slot  30 , in association with removal of plug  24 . 
     If mold release agent  33  is water soluble, pressurized water is caused to flow through rinsing tube  59  to back hull surface  34  so as to contact all or a substantial portion of the water soluble mold release agent  33  which coats plug  24 , thereby dissolving water soluble mold release agent  33 . Some inventive embodiments utilize, for coating plug  24 , a mold release agent  33  which is soluble by a liquid other than water; in accordance therewith, the appropriate liquid is utilized is a similar fashion for accomplishing dissolution of the liquid soluble mold release agent  33 . 
     Once mold release agent  33  has been dissolved, rinsing tube  59  and retaining collar  60  are preferably removed from venting tube  40  prior to venting by means of venting tube  40 , in order that venting tube  40  effectively conduct the flow of air during withdrawal of plug  24 . 
     Subsequent to disconnection of rinsing tube  59  from venting tube  40 , while venting tube  40  is appropriately situated the practitioner begins to slidably move plug  24  in a frontward or forward direction (toward the practitioner) as shown by arrow f. Properly inserted venting tube  40  allows air to vent into the resultant void  44  while plug  24  is being displaced from cured elastomer hull coating  38 . The volume of elastomeric void  44  increases in accordance with amount of retraction of plug  24 . Mold release agent  33 , which covers plug  24 , eases removability of plug  24  from the surrounding elastomer  38 . 
     Referring to FIG. 10, when plug  24  is completely removed, chamber-like cavity  46  remains, comprising empty hole  20  and empty elastomeric void  44 . 
     With reference to FIG. 11, sensor  48  is coated with lubricating agent  50 , thereby allowing for easy insertion into elastomer  38 . Small diameter metal venting tube  40  (the same as, or similar to, the venting tube  40  used for removal of plug  24  as shown in FIG. 8) is inserted through the peripheral slot  30 . Venting tube  40  is caused to enter slot  30  at front hull surface  32 . 
     Insertion of venting tube  40  can be accomplished prior to, and/or approximately contemporaneous with, insertion of sensor  48 . The practitioner will exercise ordinary skill in accomplishing, without difficulty, installation of sensor  48 ; that is, the practitioner will bring to bear the requisite degree of finesse for coordinating his/her efforts in association with venting tube  40  and sensor  48 . 
     Depending on the inventive embodiment, the ordinarily skilled artisan may adjudge that venting tube  40  should be covered with a lubricating agent (such as lubricant  50 ) to facilitate the procedure when used in association with installation of sensor  48 . In inventive practice generally, the practitioner should consider lubricating venting tube  40  on any occasion of its insertion, including when venting tube  40  is used in association with: removal of plug  40 ; installation of sensor  48 ; and, removal of sensor  48 . 
     Depending on the inventive embodiment, the practitioner will: (i) completely advance venting tube  40 , then proceed to advance sensor  48 ; or, (ii) advance venting tube  40  and sensor  48  approximately at the same time; or, (iii) at various times, advance venting tube  40  and sensor  48  together or separately. Regardless of the technique, the practitioner should be sure to position the onward end of protrusive venting tube portion  42  (the portion of venting tube  40  which extends behind back hull surface  34 ) so that it precedes the onward end of protrusive sensor portion  52  (the portion of sensor  48  which extends behind back hull surface  34 )—in particular, so that venting tube  40  appropriately interacts with void  44  in advance of advancing sensor  48 . 
     In general, venting tube  40  is advanced into and through slot  30  and continued to be advanced huggingly along the adjacent elastomer  38 . Venting tube  40  is moved by the practitioner in a backward direction (away from the practitioner), approximately as shown by arrow b, far back as necessary to continually effectuate venting during advancement of sensor  48 . The practitioner also moves sensor  48 , slidably in a backward direction (away from the practitioner), approximately as shown by arrow b. 
     Properly inserted venting tube  40  allows air to vent from void  44 , in front of the advancing sensor  48 , while sensor  48  advancing into cured elastomer hull coating  38 . The volume of elastomeric void  44  decreases in accordance with amount of advancement of sensor  48 . Lubricant  50 , which covers sensor  48 , eases insertability of sensor  48  within the surrounding elastomer  38 . 
     Still referring to FIG.  11  and also referring to FIG. 12, venting tube  40  is removed after sensor  48  is fully installed—i.e., after sensor  48  is completely flush with the surrounding elastomer  38 . Generally, when sensor  48  is completely inserted, protrusive venting tube portion  42  will extend behind back hull surface  34  approximately as far as will extend protrusive sensor portion  52 . Upon complete installation of sensor  48 , venting tube  40  is removed by being withdrawn approximately in the direction shown by arrow f in FIG.  9 . 
     When in the fully inserted position, as shown in FIG. 12, sensor  48  has protrusive sensor portion  52  which extends aft of back hull surface  34 . As shown in FIG. 12, the exterior surface of protrusive sensor portion  52  is flush on all sides with respect to the interior surface of elastomeric void  44 . For many inventive embodiments, a removable sensor mount  54  is installed on sensor  48  in order to permanently mount sensor  48  to submarine hull  22 . 
     The three-dimensional geometric shape of plug/sensor  24 / 48  can have attributes of curvilinearity and/or rectilinearity. In accordance with many embodiments of the present invention, plug/sensor  24 / 48  is approximately or substantially characterized by an axially symmetrical shape, such as parallelipiped (e.g., box-like), cylindrical or conical section. However, according to this invention, plug/sensor  24 / 48  need not be characterized by symmetry or regularity of any kind. There are two basic inventive requirements regarding the shape of plug/sensor  24 / 48 . 
     First, the shape of plug/sensor  24 / 48  must permit installation and removal of plug/sensor  24 / 48 . Plug/sensor  24 / 48  must be characterized by a shape which lends itself to such installation in a forward direction (generally in accordance with arrow f, either parallelly or coincidentally) and removal in a backward direction (generally in accordance with arrow b, either parallelly or coincidentally). Direction arrows f and be are opposite counterparts of the same bidirection, i.e., a forward direction and a backward direction which are coincidental or parallel. 
     During installation or removal according to many inventive embodiments, plug/sensor  24 / 48  traces a path which is approximately straight (linear). However, according to this invention, the path traced by the advancing or withdrawing plug/sensor  24 / 48  can be straight, curved and/or jagged—so long as the inventive bidirectional movement (in both opposite ways) of plug/sensor  24 / 48  is inventively practicable. Plug/sensor  24 / 48  must be sufficiently freely movable in both the forward and backward directions; that is, without undue difficulty, the plug/sensor  24 / 48  must be completely introducible into, and completely withdrawable out of, the conformal cavity. 
     Second, the shape of the plug/sensor  24 / 48  must permit insertion and removal of venting tube  40 . It can be conceived that plug/sensor  24 / 48  is characterized as having a surface portion which lends itself therealong to such insertion and removal. A slot  30  must be providable at the perimeter of hole  20  in wall  22 . Venting tube  40  must fit through slot  30  and be completely insertible in, and removable from, conformal chamber-like cavity  46 , while venting tube  40  is moving (e.g., sliding) tangentially along an adjacent surface portion of plug/sensor  24 / 48  and/or an adjacent surface portion of elastomeric void  44 . 
     Inventive practice will generally demand a firm and rigid external construction of both plug  24  and sensor  48 . The composition of either plug  24  or sensor  24 / 48  can include any material having these properties, such as wood, metal, plastic, hard rubber or composite. According to frequently preferred inventive practice, plug  24  is a solid piece made of a strong material (e.g., plastic or rubber) which has been molded, in a conventional process, in geometric likeness to or identity with sensor  48 . Some inventive embodiments provide a solid hard rubber plug  24  which is analogous to an ice hockey puck. A typical sensor  48  or other device which is inventively installed will have a metallic or plastic casing. 
     Generally, in inventive practice venting tube  40  will have to be sufficiently rigid to permit insertion into the cavity. For most inventive embodiments venting tube  40  will be straight and rigid, although venting tube  40  could conceivably be slightly or moderately curved and/or slightly or moderately flexible for some inventive embodiments. 
     Described herein in relation to FIG.  7  through FIG. 12 are some inventive embodiments wherein submarine hull  22  is relatively thin, and a substantial portion of the installed device (protrusive sensor portion  52 ) extends beyond hull  22  and into elastomeric layer  38 . Frequently, such inventive embodiments require implementation of mechanical means such as a removable plug retaining plate  35  (for plug  24 ) and a removable sensor mount  54  (for sensor  48 ). 
     However, according to some inventive embodiments, the structural wall (e.g., submarine hull  22 ) is thick enough to enable threaded engagement of the device (e.g., sensor  48 ) with the structural wall, and/or threaded engagement of the plug (e.g., plug  24 ) with the structural wall. Referring to FIG.  13  and FIG. 14, the installed object (which appears in two dimensions to be rectangular and trapezoidal, respectively, in FIG.  13  and FIG. 14) can be conceived to be either sensor  48  or plug  24 . The cross-sectional shape of plug/sensor  24 / 48  is approximately circular such as shown in FIG.  4 . 
     As shown in FIG.  13  and FIG. 14, hull  22  is thick enough to permit threaded engagement  56  of the circumferential outside surface of device/plug  24 / 48  with the circumferential inside surface of the hole  20  in hull  22 . A portion of the outside circumferential surface of cylindrical plug/sensor  24 / 48  is threaded like a screw. The inside circumferential surface of hole  20  is threaded in complementary fashion. Plug/sensor  24 / 48  is shown in FIG. 13 to be approximately cylindrical. Plug/sensor  24 / 48  is shown in FIG. 14 to be cylindrically tapered—i.e., shaped like a section of a cone. 
     Still referring to FIG. 13 and 14, and again referring to FIG.  7  through FIG. 12, installed plug/sensor  24 / 48  is shown in FIG.  7  through FIG. 12 to approximately be flat and vertically even with front hull surface  32 . However, in inventive practice, neither sensor  48  nor plug  24  need be vertically even with front hull surface  32  when installed. 
     With reference to FIG.  13  and FIG. 14, threaded engagement  56  of plug/sensor  24 / 48  with hole  20  obviates the need for approximate vertical evenness of plug/sensor  24 / 48  with front hull surface  32  (although such disposition may nonetheless be desirable in particular applications). That is, frequently unnecessary in practicing such inventive embodiments is the utilization of either a removable retaining plate  35  to secure plug  24 , or a removable mount  54  to secure sensor  48 . Installed cylindrical plug/sensor  24 / 48  shown in FIG. 13, and installed conical plug/sensor  24 / 48  shown in FIG. 14, each have a frontally projective portion  58  (indicated by dashed line) which juts out forward of front hull surface  32 . 
     Other embodiments of this invention will be apparent to those skilled in the art from a consideration of this specification or practice of the invention disclosed herein. Various omissions, modifications and changes to the principles described may be made by one skilled in the art without departing from the true scope and spirit of the invention which is indicated by the following claims.