US3027610A - Method of protecting timbers against marine borer attack - Google Patents

Description

METHOD OF PROTECTING TIMBERS AGAINST MARINE BORER ATTACK Filed June 4, 1958 O. E. LIDDELL April 3, 1962 3 Sheets-Sheet l -"1"" INVENTOR. 'v/ 520. 0/2/41. 5 4/005 BY f 7 fi :11; M

fltomee 6 April 3, 1962 Filed June 4, 1958 o. E. LIDDELL 3,027,610

METHOD OF PROTECTING TIMBERS AGAINST MARINE BORER ATTACK 3 Sheets-Sheet 2 INVENTOR. 0mm E. 000511.

vizier/23,5

o. E. LIDDELL 3,027,610

METHOD OF PROTECTING TIMBERS AGAINST MARINE BORER ATTACK April 3, 1962 5 Sheets-Sheet 3 Filed June 4, 1958 ufrl glill:52???" R. mM 5 m a a H T W I m r M a F? 1 T. i L E :E u w. T r a m; H WW 0 v T. \.i .1: Y E E E E B 3,627,619 h IEIHSI) PRGTEQTING TIMBERS AGAINST li IARINE IlGRER ATTAEK Grval E. Liddell, R0. Box 142, Avalon, Calif. Fiied June 4, 1953, Ser. No. 739,771 4 Eiairns. (til. Ell-1W) The present invention relates to a novel method for the protection of submerged wooden structures against marine borer attack.

It is a major object of my invention to provide an improved means and method of protecting a submerged wooden structure against marine borer attack.

Another object of my invention is to provide a method for contracting a loosely fitted tubular encasement into engagement with a pile throughout the length of the encasement from the surface of the body of water in which the pile is located without the aid of any underwater workers.

Yet another object of the invention is to provide a method of applying a protective encasement of this type within a limited working space, as between the deck of a pier and the water line, and by unskilled workers working on the surface of the water without the use or" specialized equipment whereby installation can be accomplished without removal of the decking.

A further object of the invention is to provide a method of this type capable of use on all lengths and diameters of piles and especially on older but still usable piles such as have had large surface areas eaten away by borers so that they no longer have a uniform taper or diameter.

It is also an object of the invention to provide an encasement for piles that can be fabricated from commercially available materials at a cost lower than that of prior devices and having a simplified method of installation whereby the expense of protecting new and old piles against marine borer attack is greatly reduced.

A more particular object of the present invention is to provide a method of protecting a submerged wooden pile against marine borer attack by wrapping a sheet of pliable substantially waterproof material about said pile until said sheet engages said pile throughout the pile section to be protected. Thereafter, the sheet is secured about said pile to define a generally circumferentially water-filled space between the pile and the sheet to thereby restrict circulation between said space and the water surrounding said sheet. In this manner the water in said space is maintained stagnant and marine borers are prevented from sustaining themselves within this space.

These and other objects and advantages of my invention will be apparent from the following description thereof when taken in conjunction with the annexed drawings in which:

FIGURE 1 is a plan view of a first form of encasement embodying my invention;

FIGURE 2 is a partial sectional view, on an enlarged scale, taken along the line 2-2 of FIGURE 1 and showing a first form of pole piece construction;

FIGURE 2a is a view similar to FIGURE 2 showing another type of pole piece construction;

FIGURE 3 is a perspective view showing a method of installation of the encasement illustrated in FIGURE 1;

FIGURE 4 is a horizontal sectional view showing an encasement loosely arranged in tubular configuration around a pile and indicating the method of contracting the encasement into snug engagement with the pile;

FIGURE 5 is a View similar to FIGURE 4 but showing the encasement in fully contracted condition;

FIGURE 6 is a partial sectional View of the area 6 of FIGURE 5, on an enlarged scale, particularly showing 3,027,619 Patented Apr. 3, 1962.

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the method of maintaining the encasement in snugly fitting engagement with the pile;

FIGURE 7 is a partial sectional view, on an enlarged scale, taken along the line 77 of FIGURE 1 and showing a first form of socket means for holding a pair of pole pieces together;

FIGURE 7a is a view similar to FIGURE 7 showing another form of socket construction;

FIGURE 8 is an elevational view of an encasement in place on a pile with a skirt portion at the lower end thereof held closed against the pile by a novel form of skirt closing means;

FIGURE 9 is a perspective view showing the form of skirt closing means utilized in FIGURE 8;;

FIGURE 9a is a partial perspective view, on an enlarged scale, showing certain details of construction of a skirt closing means;

FIGURE 10 is a view similar to FIGURE 8 showing a form of protective boot applied over the lower end of the encasement and showing another form of band for closing the upper end of an encasement, another boot being illustrated in position for lowering into place above the upper end of the encasement;

FIGURE 11 is a partial elevational view, on an enlarged scale, showing the upper end boot of the encasement in place;

FIGURE 11a is a view similar to FIGURE 11 showing an alternate form of upper end boot;

FIGURE 12 is a horizontal sectional view, on an enlarged scale, taken along the line 12-12 of FIGURE 10;

FIGURE 13 is a perspective view of an alternate form of closing band particularly adapted for use at the upper end of an encasement;

FIGURE 14 is a plan view of a part of another species of encasement of my invention;

FIGURE 15 is a partial sectional view, on an enlarged scale, taken along the line 15-15 of FIGURE 14;

FIGURES 16 through 20 are elevational views illustrating successive steps in applying the encasement sheet of FIGURE 14 to a pile;

FIGURE 21 is a horizontal sectional view, on an enlarged scale, taken along the line 21-21 of FIGURE 18 illustrating the manner of contracting the encasement into intimate engagement with the pile; and V FIGURE 22 is a detail sectional view, on a further 'enlarged scale, of the area 22 of FIGURE 21.

In the drawings, I have illustrated my improved encasement as being particularly adapted for application to piles. that the principles of construction herein disclosed are not necessarily so limited and can be utilized with certain other types of submerged structures.

In general the encasement comprises a substantially rectangular sheet of a pliable material preferably tailored to conform to the dimensions of the pile to which it is to be applied, including any taper that may be present on, the pile. This sheet is rigidly reinforced against bending along at least a portion of the opposite vertical edges of the sheet. The rigidity of the reinforced edges enables the entire unit to be manipulated from the surface of the water, as from a small skiff, to arrange the encasement in tubular configuration around the pile. Thereafter, the pair of reinforced edges are brought together and rotated in unison to contract the encasement into engagement with the pile. A fastening means on the pair of reinforced edges is then connected to the pile to hold the reinforced edges against counter rotation whereby the engagement of the encasement around the pile is maintained.

The encasement sheet is preferably made of a waterproof material which is also preferably elastic, but it is believed that neither of these qualities is essential. I

However, it will appear to those skilled in the art prefer to use rubber or neoprene which have these qualities but may also use polyvinyl chloride which has these qualities to a lesser degree, or may use a woven fabric which is practically inelastic and still less waterproof. The sheet should be substantially waterproof, however, in the sense that while it may be porous the ratio of the volume of pores or interstices to the volume of mass restricts the circulation of sea water around the encased timber to such an extent that the rate of circulation is less than that required to sustain marine borer life. When the salt, oxygen and organic matter which the borers extract from the sea to sustain themselves are not supplied at a sufficiently high rate the borers die as a consequence. the extent to which the rate of circulation must be restricted will vary according to the type of borer, the salt, oxygen and organic matter content of the sea and other local conditions and is therefore subject to many variables.

In any event, the total rate of circulation into the encasement, through the material of the sheet or into the ends of the encasement, must be low enough to arrest or prevent marine borer activity, i.e. create a toxic condition of stagnation inside the encasement wherein the wa ter lacks supplies of salt, oxygen and organic matter in amounts sufiicient to sustain life.

In the drawings I have shown two specific species of encasement with two different modes of application to piles. In each case, the encasement is shown with certain details of construction. However it is to be understood that such details of construction are not necessarily confined to the species of encasement with which they are shown and in many instances can be applied to either of the illustrated species of encasement.

Referring now to FIGURE 1, a first species of encasementisillustrated therein and identified generally by the numeral 30. This encasement includes a substantially rectangular thin sheet 32 of a pliable substantially waterproof material, preferably elastic in nature, cut to a length at least as great as the area of the pile to be protected against marine borer attack. The sheet 32 throughout its length is of a width preferably greater than the corresponding circumference of the pile and the opposite vertical edges 34 of the sheet are preferably cut with a taper conforming to the taper of the pile. Where the area of the pile which is to be protected is relatively short, the taper of the pile can be ignored. However in order to achieve aneat construction it is ordinarily preferable to tailor the sheet with tapered opposite vertical edges.

Each of the edges 34 is rigidly reinforced against bending by a pole piece 36 whose detail construction is illustrated in FIGURE 2. Each of the pole pieces 36 includes a semi-cylindrical filler member 38 of wood, metal, plastic or the like over whose arcuate face one edge portion of the sheet 32 is placed. A semi-cylindrical member 40, preferably of metal and having a cavity adapted to receive both the edge portions of the sheet 32 and the filler member 38, is then placed around these elements and the Whole held in assembled relationship by a plurality of rivets 42 or other suitable fastening means. The metal parts can be made of ordinary steel, galvanized metal, copper alloy or hearing metals such as brass or Monel metal, and like materials such as are adapted to resist the corrosive effects of sea water.

Instead of the pole piece construction just described, in some cases it is preferable to employ a pair of pole pieces 36a of the type shown in FIGURE 2a. This alternative comprises a semi-cylindrical wooden member, preferably creosoted to resist attack by marine borers. It is to be understood however that treatment with creosote or other artificial chemical agents is not essential since the wooden pole pieces 36a can be protected against borers in the same way as a pile; i.e. by wrapping them in portions of the sheet 32. I have also found that while many species of wood are satisfactory for use as pole l pieces, a close, straight grain wood such as clear white pine or apitong mahogany is preferred.

Referring now to FEGURE 1 it will be seen that both of the pole pieces 36 extend upwardly above the upper edge of the sheet 32 but at the lower ends terminate above the lower edge of the sheet 32. In order to expose the lower ends of the pole pieces 36 so that they can be coupled in a manner hereinafter set forth, the opposite vertical. edge as of the sheet 32 are cut out and relieved as indicated at 44. As is indicated in FlGURES 2 and 2a the pole pieces are preferably afiixed to the vertical edges of the sheet 34 with their flat sides on the same surface of the sheet. Thus, when the encasement 39 is placed in tubular configuration around a pile the flat sides of the pole pieces face one another and their lower ends are exposed to one another without any barrier of portions of the sheet 32.

Those portions of the pole pieces 36 which extend above the upper edge of the sheet 32 provide a pair of handles 48 by means of which the encasement 36 can be manipulated for placement around a pile St) in the manner shown in FIGURE 3. Thus, a man standing in a skiff or the like on the surface of the water can hold both pole pieces 36 in one hand by means of the hendles 48 while the other hand is passed around the pile. The other hand then takes one of the pole pieces 36 to draw the sheet 32 around the pile Sii. It will particularly be observed that the encasement 30 for the major portion of its length can be submerged in the body of water 52 during this operation and the encasement 30 will therefore assume a buoyancy which makes it relatively easy for a single man to manipulate even a very long encasement 3ft. It also frequently happens that a number of piles will be closely spaced together so that it would be quite diificult to apply a tubular casing thereto by first aligning it above the pile and then lowering it around the pile. With the method of installation just described, as long as there is sufiicient space between adjacent piles for a person to pass his hand therethrough, or to admit the thickness of one of the pole pieces 36 my improved encasement can quite easily be placed around the pile. This method of installation is also important in those instances where a deck (not shown) is supported on top of the piles in close proximity to the Surface of the body of water 52. Where the upper end of the piles are obstructed-whereby working space is limited in this fashion no difficulty has been encountered in making successful installations of encasements.

After the encasement 3% has been wrapped around the pile 50 in the manner shown in FIGURE 3 the lower ends of the two pole pieces 36 are releasably joined by means provided on the lower ends of the two pole pieces. The lower end of one of the pole pieces 36 is provided with a semi-cylindrical socket 525 having a cavity 54 adapted to loosely or slidably receive the exposed lower end of the wooden member 38 of the other pole piece 36, the socket 52 being held on its pole piece 36 by screws 56 or other suitable fastening means' As is indicated in FIGURE 3, by manipulation of the handles 48, the exposed lower end of the wooden member 38 of the one pole piece 36 can be inserted into the cavity 54 of the socket 52 on the other pole piece 36. Thereafter the two pole pieces 36 are brought together to define a substantially cylindrical unit or assembly.

FIGURE 7a illustrates another type of socket 52a on one of the wooden pole pieces 36a. In this case a semicylindrical cavity 5% is defined by a portion of the sheet 32 such as would otherwise be a part of one of the cutout portions 44. Alternatively the socket 52a can be made of a separate piece of elastic waterproof material vulcanized or otherwise afiixed in position on the sheet 32. The socket 52a is utilized in precisely the same manner as the socket 52.. To facilitate connection of the two pole pieces, the socket cavity can be enlarged and can also be tapered.

.AA A .11

After the two pole pieces 36 have been brought together to define a complete cylindrical enclosure around the pile 50, the encasement 30 is moved to the desired vertical position on the pile. Thereafter the pair of pole pieces 36 are rotated in unison, as is indicated in FIGURE 4, to contract the encasement 39 into engagement with the pile t} (FIGURE 5). The force of this engagement will be sufficient to hold the encasement 30 against slipping downwardly on the pile 50. However, in order to aid in holding the encasement 36 in place, but primarily to hold the pair of pole pieces 36 against counter-rotation in a direction such as would permit loosening of the sheet 32, a lag bolt 60 is inserted through aligned bores 62 in the handle portions 48 of the pole pieces and fastened directly to the pole 50.

I have found that the use of a socket at the lower end of the pole pieces and a fastener, such as the lag bolt 6% at the upper end of the pole pieces is ordinarily sufiicient to hold the two pole pieces together during contraction of the encasement. However, in some instances it may be desirable to fasten the two pole pieces 36 or 364: together at spaced intervals along their length. For such a purpose I have shown in FIGURE 1 a plurality of spaced bores 64 in one pole piece 36 adapted for alignment with other bores 64 formed in the other pole piece. When the two pole pieces 36 are brought together suitable fasteners can be inserted through the aligned bores 64 to securely maintain the pair of pole pieces in assembled relationship.

In order to protect the pole pieces against deterioration from exposure to the water, and in the case of wooden pole pieces 36a, to prevent attack by marine borers, it is preferable that the sheet 32 have a width greater than the circumference of the pile 50 as is indicated in FIG URE 4. This excess width should be at least sufficient to wrap the pair of pole pieces in edge portions of the sheet 32 one or two times when the pair of pole pieces are rotated to contract the encasement against the pile 5t). Thereafter, the pair of pole pieces are protected against the corrosive efiect of the ambient water or against marine borer attack.

The wrapped pair of pole pieces 36 and edge portions of the sheet 32, have a substantial combined girth. As a result, a part of the sheet 32 extends tangentially between the pile 59 and the wrapped pole pieces 36 leaving gap 66 between the sheet 32 and pile 50 running the length of pole pieces 36. As a result, some of the ambient water may circulate through the gap 66, thus hindering the maintenance of a stagnant condition inside the encasement. In some ports or geographical locations this may not be critical, but in other localities where marine borer attack is severe and continuous it is desirable to close the gap 66, at least at the lower end of the encasement 39.

A skirt 46, comprising a portion of sheet 32 depending beneath the pole pieces 36, aids in closing the gap 66 at the lower end of the encasement 30, and in protecting the extreme lower ends of the pole pieces 36 against exposure to the sea water or marine borer attack. Since the pole pieces 36 terminate short of the lower end of the sheet 32, the skirt 46 can be completely circumferentially clamped against the pile 50 without obstruction by the pole pieces 36 so that formation of any gap in the skirt portion of the sheet 32 is avoided. It will be understood however that the skirt 46, like the balance of the sheet 32, is in contact with the pile 50 for the major portion of the circumference of the pile and is open only at gap 66. However a complete band around the skirt 46 can be very readily applied and enhances the intimacy of the engagement of the skirt with the pile 5i} p and therefore the use of a complete circular band is preferred, rather than some less than circular means adapted to fit only over the gap 66.

The skirt closing bands can be made of any suitable plastic material. A preferred form of such band is indi cated in FIGURE 9 and indicated by the numeral 68. This band 68 has a length approximately the same as the circumference of pileStl. one end band 63 is formed with a longitudinally elongate eye 70 adapted for cooperative engagement by a hook 72 formed in the opposite end of band 68. Since band 68 is preferably in a state of tension when applied to the skirt 46, the eye 76 and hook 72 should be of such a configuration as to avoid rupture of the material of the band, particularly at the eye 70. This is important for insuring a long service life for the band 63.

To accomplish this, the eye 76 comprises a longitudinally elongate slit 74 of a length approximately the same as the width of band 63 and terminating at both ends in arcuate openings '76 adapted to avoid the concentration of rupturing stresses in the ends of eye 79 when hook 72 is placed therein. The hook 72 is generally T-shaped in configuration and has a stem section 78 which is wider on the inside of band 68 than on the outer surface of the band. The stem 78 is therefore wedge-shaped in cross section and narrows as it develops toward the adjacent end of the band 68. The head 80 of hook 72 is of the same width as the major portion or the band 68 proper and has a junction with the stem portion 78 in a pair of opposite shoulders 82, which are preferably CtIlgUi'aily related and convergent towards the adjacent end of the band 68.

The band 68 can be installed either from the surface of the body of water 52 or by a diver. With the former procedure the hook 72 and eye 74) are connected after band 63 has been placed around the pile 5 or around the upper end of the encasement 3t Thereafter, even through the band 68 is under tension, it can he slid downwardly over the encasement 31) until it snaps or contracts into place around skirt 46 after passing over the lower end of the pole pieces 36. This can be accomplished by using a pair of long poles, notched at their lower ends to hold the band, inserted on opposite sides of the pole between the pile and band, to push the hand down. As is apparent, when the band 63 is to be installed by a diver it can be carried in open condition to the bottom of encasement 30 by the diver, who thereafter stretches it around the skirt 46 and then connects the hook 72 through the eye 70. In making this connection it is preferable to twist the head 89 of hook 72 90 from its normal condition to pass it through the slit 74 of eye 70, which is of approximately the same width as the head 3t After engagement it will be noted that the wedge-like contiguration of stem portion 78 of the hook 72 prevents a sharply divergent separation of the opposite sides of the slit 74 of eye 70 so that concentration of stresses is minimized.

It will be apparent that other fastening means can be utilized in lieu of the hook-and-eye means 70 and 72. For example, opposite ends of an elastic band can be vulcanized or cemented together, or stapled or riveted. However these alternate fastening means involve expenditures of time and labor which are avoided by the band 68. Vulcanizing or cementing involve lapses of time merely in waiting for the joined parts to be securely connected and also require the use of specialized equipment. On the other hand the band 68 can be fabricated easily, even in the field.

The upper end of the encasement 30 will normally be positioned above the high-tide line of the body of water 52 where it will usually be safe from marine borer attack. If desired, the further precaution may be taken of closing the gap 66 at the upper end of the encasement 30 in order to restrict circulation of the ambient Water therein. due to Wave action. Where closure of the upper end of the encasement 30 is desired a band 84-, such as that shown in FIGURE 13, can be employed for the purpose.

The band 84 is also preferably made of a rubber-like material and includes an integral rigid U-shaped section 86 adapted for semi-circularly embracing the pair of Wrapped pole pieces 36 at the upper end of the encasement 30. The U-shaped portion 86 may be defined by a complementarily shaped metal insert molded within the band 34 or may be otherwise reinforced against separation of the opposite arms thereof when the band 8 5 is stretched. in use, the band 84 is positioned at the upper end of the encasement 30' with the wrapped pole pieces as received within the U-shaped portion 86, thus closing the gap 60. Thereafter, the ends 84 can be vulcanized or cemented together. Alternatively the opposite ends of the band 04 can be formed with hook-and-eye means '70-72 as illustrated in FIGURE 11a.

In order to minimize the circulation of Water behind the encasement 30 I have utilized a pair of elastic boots 83, also preferably made from a rubber-like material. Such boots can be used in addition to, or in lieu of the gap closing bands. Referring to FIGURE it will be seen that the boots 88 comprise relatively Wide elastic bands Whose opposite ends are vulcanized or cemented together after the band has been stretched and placed in tension around the pile 50. This operation preferably takes place on the pile above the upper end of encasement 30. After fabrication, one band 88 is expanded by any suitable means, such as a plurality of poles, and guided and slipped downwardly over the pile 50 and encasement 30 to be positioned around the skirt 46, immediately beneath the lower ends of the pole pieces 36. Another band 88 is then slipped down to the position indicated in FlGURE 11 to embrace both the pile 50 and the extreme upper end of the pole pieces 36 and sheet 32.

Another form of boot 90 is illustrated in FIGURE 11a. In this instance the boot 90 comprises a relatively wide band of rubber-like material wrapped in a position around the pile 50, the extreme upper end of pole pieces 36, and the upper edge of sheet 32 and is held in place by nails or other suitable fasteners 92. It will be observed that the nails $2 are not driven through any part of the sheet 32 since itis desirable to maintain the integrity of the sheet.

If desired, any of these boots which are to be used at the upper end of an encasement can be made of a heavy material to also serve as fenders. The boots can also be relatively short encasements secured in place by a fastener in their pole pieces and the pole pieces placed on top of the gap 66 of the main encasement to close the gap.

Depending upon local conditions, the area of the pile which is subject to marine borer attack may extend from well above the tide line to the mud line of the body of water. Although the encasement 30 has been illustrated in the drawings as being finally installed with its lower end terminating above the mud line 92 of the body of water 52, it is tobe understood that, with or without the skirt portion 46, it can equally well be installed with its lower end positioned beneath the mud line 92. By the same token, the alternate form of encasement 100 illustrated in FIGURES 14 through 21, while illustrated as being finally installed with its lower end beneath the mud line 2, can equally well be installed in the position illustrated for the encasement 30.

The encasement 100 is particularly well adapted for application to extremely long piles 102 where the pile must be protected down to the mud line 92 of the body of water 52. As with the encasement 30, it may frequently be necessary to make such installation within a limited working space as when a decking is supported On the piles 102 in close proximity to the surface of the body of water 52. It is, of course, desirable to be able to make such an installation Without tearing up any decking and it is also desirable to be able to make such an installation entirely from the surface of the body of water 52 without the aid of any underwater workers.

8 he encasement 100, like encasement 30, has particular utility in situations such as those just mentioned.

Encasement comprises a substantially rectangular sheet 10 of a substantially Waterproof pliable material and a tubular pole piece 106. The sheet 104 is made of the same class of materials as sheet 32 and is of a length. sufiicient to reach from a point above the mean tide level of the body of water 52 down to a point one or two feet below the mud line 92. This sheet 104 is also preferably tapered to conform to the pile taper and has a width throughout its length exceeding the corresponding circumference of the pile 102, this excess width preferably being sufiicient to provide enough material to wrap the pole piece 106 within the pair of vertical edge portions of the sheet 104 when the sheet is contracted into snug engagement with the pile 102.

Each of the opposite vertical edges of the sheet 104 is provided with an enlarged bead 103 that is preferably integrally formed and semi-cylindrical in configuration, both of the heads 108 preferably being disposed on the same surface of the sheet 104. However, it will be apparent that the beads may assume other configurations and may also be separately formed and afixed to opposite vertical edges of the sheet 104 by vulcanizing, cementing, or suitable fasteners.

The pole piece res is preferably made of a metal, such as Monel, adapted to successfully resist corrosion from sea water action but may also be of wood or plastic. As indicated in FIGURE 22, the pole piece 106 is thin walled, but should have sufiicient rigidity to support the sheet 104 during installation and be capable of withstanding the forces applied to it during the twisting operation without undue distortion. Along one side, the pole piece 106 is formed with a longitudinally extending slot 110, preferably running the entire length of the pole piece 106, and this slot should be wide enoughto easily accommodate twice the thickness of the intermediate portions of the sheet 104, so that a double thickness of sheet 104 can be readily slid through the slot 110. By the same token, the interior diameter of the tube 106 should be large enough to easily slidably accommodate the pair of beads 103. The combined thickness of the beads 108 is greater than the Width of the slot 110 whereby th eedges of the sheet 104 are restrained against movement radially outwardly of the pole piece 106.

In the installation of the encasement 100, the sheet 104 is rolled up about a transverse axis on a spindle or other suitable support and held in position adjacent the upper end of the pile 102. The pole piece 106 is then placed in a vertical position adjacent the pile 102 with its lower end supported on the bottom or mud line 92. It will be observed that the pole piece 106 is disposed on the side of pile 102 opposite from the rolled up sheet 104 and the slot 110 of pole piece 106 confronts the pile 102. The pair of beaded edges 108 of the free end of the sheet 104 are then slid into the open upper end of the pole piece 106 with a double thickness of the sheet 104 slidably entering the slot 110. Thus, as the sheet 104 is slid downwardly over the pile 102 and as the beaded edges 108 concurrently are moved downwardly through the pole piece 106, the sheet as it is unrolled assumes a tubular configuration surrounding the pile 102.

This installation of sheet 104 around pile 102 can be accomplished, if desired, with the aid of a diver to pull the sheet 104 downwardly. However, in order to make an installation of encasement 100 entirely from the surface of the body of Water 52, a pusher rod 112 can be used, such as is generally shown in FIGURE 17. The pusher rod 112 is conveniently made up of a number of telescopically connectable short tubular sections 114. A lowermost section 116 is provided at its lower end with a clamping means 118 for gripping the lower edges of the sheet 104. The clamp means 118 is actuated by an elongate member (not shown) passing through the tubular sections 114 and 116 and connected to a handle device 1 at the upper end of rod 112 for releasing the clamp means 118 from engagement with the sheet 104. As many tubular intermediate sections 114 as desired can be employed for making up a pusher rod 112 of the length necessary to push the sheet 164 downwardly to the mud line 92 and through the pole piece 106.

To facilitate contraction of the sheet 104, the sheet should be pushed downwardly to a position in which its upper edge is beneath the upper end of the pole piece 106 whereby a handle portion 122 of the pole piece projects above the upper edge of the sheet 104. At the same time, if it is desired to have a skirt portion 124 at the lower end of the sheet 194, the sheet 104 should be pushed downwardly until its lower end is beneath the lower end of the pole piece 106.

When the encasement 109 is in the position of FIG- URE 18, the pusher rod 112 is removed by actuation of the handle portion 122. Thereafter, the pole piece 106 is rotated, as indicated by the directional arrow 126 in FIGURE 21, in order to take up the slack in the sheet 104, but not fully contracting the sheet into engagement with the pile 192. A lance 128 is then directed to the junction of the pile 102 with the bottom 92 and compressed air or water directed through the lance to create a small crater 13%, one or two feet in depth. Since the encasement llltl has already been preliminarily closed into contact with the pile 1&2, none of the material removed from the crater 130 will enter thereinto. In some instances, if the water is made turbid by the action of the lance 128, it may be desirable to employ the services of a diver to ascertain that the crater 130 is properly formed. Alternatively, the diver may, of course, create the crater 130 with hand tools.

After removal of the lance 128, encasement 10b is lowered into its final position, indicated in FIGURE 20, with its lower end seated in the bottom of the crater 130. Pole piece W6 is then further twisted in the same direction until the sheet 1d4 fits smoothly around the pile 102. A lag bolt 132 is then inserted through a bore 134 in the handle portion 122 of the pole piece 106 and fastened into the pile 1&2 whereby the pole piece 106 is held against counter-rotation and the fit of the encasement 1% on the pile 162 is maintained. Tidal action of the body of water 52 will very shortly fill in the crater 13% so that the lower end of the encasement 104) is efl'ectively sealed against penetration by marine borers or excessive circulation of water.

If desired, a suitable band or other clamping means may be alfixed around the skirt portion 124, in the same manner as with the encasement 30. Similarly, the upper end of encasement 1% can also be further closed by a clamping band. If desired, any water entrapped within the pole piece 106 can be evacuated by filling it with a material such as oil, mastic, or paint which will displace the trapped water and thus inhibit corrosion of the pole piece 106. The pole piece 1th; may be protected against corrosion by providing enough width in the sheet .104 to completely wrap the pole piece 106. The use of the single tubular pole piece 106 results in the creation of a gap similar to the gap 66 defined with the use of encasement 30. However, if desired, this gap is elfectively sealed by the back filled crater 139. If the encasement 100 is not installed with its lower end in the bottom 92, the gap can be closed, if desired, by a clamping means around the skirt 124 or, if no skirt is provided, by a clamping band similar to either one of the boots 8S and 90.

A number of important advantages arise out of the removable construction of the encasements and 100. For example, in the event of rupture of the material of the sheet of these encasements, by floating debris or other mechanical action, the encasement can be quickly removed and readily repaired by a conventional patch. If it is desired to make periodic inspections of the piles, the encasements can be removed and replaced with a minimum expenditure of time and effort to expose the pile to view to ascertain whether or not any marine borer activity is going on. This removable feature also permits vertical adjustment of the encasement to change its position to meet a change in the area of the pile subjected to marine borer attack. For example, if the mud line 92 should lower, as it will in some locations, to such an extent that it exposes the lower end of the surrounding encasement, the encasement can be quickly removed and lowered into a new position in a new crater and once again fastened into place.

In the use of these encasements, they can be applied to new pilings in lieu of any of the conventional creosote or any other protection. Alternatively, a newly creosoted pile may be put in place and left without the protection of my encasements until such time as a substantial part of the creosote has leached from the pile. These encasements are then applied to the pile to arrest any marine borer activity which has already ensued and to prevent any further marine borer attack. This greatly extends the service life of an initially creosoted pile which, without my invention, would very shortly be condemned as structurally unsound.

Although the species of the invention herein shown and described are fully capable of achieving the objects and providing the advantages hereinbefore mentioned, it is to be understood that they and the several details of construction thereof are merely illustrative and that I do not mean to limit myself to the details of construction shown and described other than as defined in the following claims.

I claim:

1. A method of protecting against marine borer attack a partially submerged structure-bearing wooden pile, the upper end of which is obstructed, comprising: positioning a sheet of pliable substantially waterproof material alongside of a section of said pile to be protected, wrapping said sheet around said pile section to dispose opposite longitudinal edges of said sheet in substantial juxtaposition extending generally longitudinally of said pile, over lapping the opposite longitudinal edges of said sheet, drawing said sheet about said pile section to reduce the effective diameter enclosed by said sheet until said sheet engages said pile throughout a substantial portion of the length of said pile section, securing said sheet about said pile section in reduced diameter condition to define a generally circumferential water-filled space between said pile and said sheet, and retaining water within said space with circulation between said space and the water sur rounding said sheet being restricted to thereby maintain the water in said space stagnant to prevent marine borer attack on the submerged portion of said pile encased by said sheet.

2. A method of protecting against marine borer at tack a partially submerged structure-bearing wooden pile, the upper end of which is obstructed, with such piling ex tending upwardly from the mud line of a body of water, comprising: forming a crater lower than the mud line adjacent said pile, positioning a sheet of pliable substantially water-proof material alongside of a section of said pile to be protected, wrapping said sheet around said pile section to dispose opposite longitudinal edges of said sheet in substantial jutaposition extending generally longitudinally of said pile, overlapping the opposite longitudinal edges of said sheet, drawing said sheet about said pile section to reduce the effective diameter enclosed by said sheet until said sheet engages said pile throughout a substantial portion of the length of said pile section, lowering said sheet until its lower end is disposed within said crater, securing said sheet about said pile section in reduced diameter condition to define a generally circumferential water-filled space between said pile and said sheet, and retaining water within said space with circulation between said space and the water surrounding said sheet being restricted to thereby maintain the water in said space stagnant to prevent marine borer attack on the submerged portion of said pile encased by said sheet.

3. A method of protecting against marine borer attack a partially submerged structure-bearing wooden pile, the upper end of which is obstructed, comprising: positioning asheet of pliable substantially waterproof material alongside of a section of said pile to be protected, wrapping said sheet around said pile section to dispose opposite longitudinal edges of said sheet in substantial juxtaposition extending generally longitudinally of said pile, stififening said opposite longitudinal edges, overlapping the opposite longitudinal edges of said sheet, drawing said sheet about said pile section to reduce the eifective diameter enclosed by said sheet until said sheet engages said pile throughout a substantial portion of the length of said pile section, securing said sheet about said pile section in reduced diameter condition to define a generally circumferentially water-filled Space between said pile and said sheet, and retaining Water within said space With circulation between said space and the water surrounding said sheet being restricted to thereby maintain the water in said space stagnant to prevent marine borer attack on the submerged portion of said pile encased by saidsheet.

4. A method of protecting against marine borer attack a partially submerged structure-bearing wooden pile, the upper end of which is obstructed, with such piling extending upwardly from the mud line of a body of Water, comprising: forming a crater lower than the mud line adjacent said pile, positioning a sheet of pliable substantially waterproof material alongside of a section of said pile to be protected, wrapping said sheet around said pile section to dispose opposite longitudinal edges of said sheet in substantial juxtaposition extending generally longitudinally ofsaid pile, stiffening said opposite longitudinal edges, overlapping the opposite longitudinal edges of said sheet, drawing said sheet about said pile section to reduce the effective diameter enclosed by said sheet until said sheet engages said pile throughout a substantial portion of the length of said pile section, lowering said sheet until its lower end is disposed within said'erater, securing said sheet about said pile section in reduced diameter condition to define a generally circumferential water-filled space between said pile and said sheet, and retaining water within said space with circulation between said space and the water surrounding said sheet being restricted to thereby maintain the water in said space stagnant to prevent marine borer attack on the submerged portion of said pile encased by said sheet.

References Eite-d in the file of this patent UNITED STATES PATENTS 62,295 Smith Feb. 19, 1867 333,204 Dolbeer Dec. 29, 1885 395,866 Anderson et al. Jan. 8, 1889 942,761 Voynow Dec. 7, 1909 1,244,119 Mulnix et a1. Oct. 23, 1917 1,252,645 Baier Jan. 8, 1918 1,353,598 Lewis ept. 21, 1920 1,546,860 Neubort July 21, 1925 1,963,436 Durnke June 19, 1934 2,385,869 Lane Oct. 2, 1945 2,659,687 Moore Nov. 17, 1953 2,757,428 Stark Aug. 7, 1956 2,853,758 Topf Sept. 30, 1958 FOREIGN PATENTS 669,489 Germany Dec. 28, 1938 331,576 Italy Nov. 9, 1935 OTHER REFERENCES Smith: Preservation of Piling Against Marine Wood Borers, U.S. Dept. of Agr., Forest Service, Circ. 128, 1908, 16 pp.; esp. pp. 8-11.

Atwood: Marine Piling Investigation, National Research Council, Washington, D.C., 1924, pp. 87-106.

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