Патент USA US2412578код для вставки
VD126- 17, 1946. F. R. HARRISl 2,412,578 DRYDOCK PONTOON CONSTRUCTION Filed Aug. ,'7, 1943 5 Sheets-Sheet l IN VEN TOR. Frederic R; Harris v i Dec. 17, T1946. 2,412,578 F. R. HARRIS vDRYDOCK PONTOON CONSTRUCTION Filed Aug. ‘7, 1945 5 Sheets-Sheet 2 | #3H l W ¿Li W BY SPÄM Dec. 17, 1946. ` F, R, HARRls , 2,412,578 DRYDOCK PONTOON CONSTRUCTION Filed Aug. '7, 1943 5 sheets-sheet 4 \“W b » NIMH HIL ¿En IMM ¿Fë‘ »uw i is à 757 A/ 5.?¿ya INVENroR. ` Frederic Ä’Jïàrns Arron/wav ' ` 2,412,578 Patented Dec. 17, 1946 UNITED STATES PATENT OFFICE 2,412,578. DRY» DUCK' PONTOON CONSTRUCTION Frederic R; Harris, New York, N. Y. Application August 7, 1943, Serial No. 497,784 11 Claims. (C1. 114-83) 2 This invention relates to the construction of with a pontoon of a multiple-unit dry dock; that hulls and especially pontoon hulls for floating dry docks. An important object of the invention is to pro is, a dry dock that is made up of. a number of v-ide an improved internal framework for a dry similar pontoons connected together side by side to form along dockfor supporting a» ship; as set iorthin my application for patent on a Multiple dock pontoon, comprisingA a novel and advanta geous arrangement of bulkheads and cooperat~ ing» trusses. The floating dry dock, adapted to lift a ship unit floating dry dock, Serial No. 482,376, ñled April 9, 1943, noW Patent No. 2,37 9,904, dated July of. ships. At ñrst a- marine Vessel comprised a shell. internally braced- by transverse frames, rigidly connected to a central keel, which eX as to extend crosswi'se of a ship in the entire dock, and placed someV distance apart, and a seriesof trusses containing K frames on both sides of; each 10, 1945. But the invention is not limited to pontoons of multiple-unit docks, and some fea out of Water and properly support it for repairs, 10 tures of the invention relate to hull construction generally. has undergone much recent development in My invention' provides bulkheads arranged so keeping with modern progress in the design of said bulkheads. Horizontal beam members-to tended over the vessel’s entire length. Therefore, resist compression extend fro'mside to sid‘e- of the in a dock, the whole ship load couldk be supported hull of the pontoon and unite the centers of the on blocks directly under the keel, which was the K frames inthe diiîerent trusses; and the frames strongest. part of the ship.` Bilge blocks were added at the sides merely toV balance the vessel on 20 at each side are further braced by beams. con necting their centers. Thus the trusses are stiff the keel blocks. ened in their various positions and, with their in The keel was afterwards replaced by a shallow creased rigidity, are' able> toÍ support high com double bottom Which, however, did not- in any pression loads. The span ofv the uprights in the substantial manner change the. docking condi trusses becomes half‘ of that in a' prior floating before tions; to andtake floating the entire dry» load docksonwere: acentral designed row or 25 dry dock. The horizontal beam members in their turn, being joined rigidly'together, willrv resist ei track of blocks, which were still. of timber and fectively the outsidey water pressures on the' sides bore the full weight of the vessel without crush andends of the'ponto'on. mg, Also my invention rendersi it feasible to rely But at the present day there are both. com upon relatively few bulkheads‘ tonv transmit in mercial and naval vesselsofv suchk great size and herent pontoon truss-bending stresses. The K weight that, even shoulda continuous keel track frame. trusses which, at their endsî are securedto be provided.k the whole length> of the dock, this some of the bulkheads, will, together' with the track would have to be sobroadthat asubstan~ tial portion of the ship’s bottom would be covered " additional bulkheads and their plating between the. trusses, render the whole interior framework thereby and made. inaccessible to workmen The so strong and rigid that all liability of Warpin’g remedy for this. is a plurality of tracks orv rows andsimilar strains in thsbulkheadsis eliminated." of blocks, side by side on the floor of thev dock; Also the trusses render the‘ deck and bottom so and a structural design for the dock-4 that is rigid that the entire deck> and` bottom: plating economical in the amount of material' used,> and willv act as flanges' for girders, the‘webs of 'which yet firm enough to withstand all working stresses are formed by' they additional bulkheads; and due to the vessel’s weight, and other forces. buckling and- other'distortion‘o‘f deck and bottom In floating dry docks of` prior construction a plates .becomes impossible. rugged, central longitudinal bulkhead is usually In addition, my invention-contemplates suflië included; with a considerable number of' trans cient additional reinforcement in the central part verse bulkheads. My invention contemplates sev of the pontoon. hull-to‘»v cooperateiwith the bulk‘ eral bulkheads for carrying and sharing the heads and trusses in realizing the fullf aim of the weight of the ship; and: both the> ship load andthe invention. buoyancy load are transmitted to said'bulkheads Another feature of> the' invention relates to a by a system of frame-trusses; andV thence- t'o ad combination of bulkheadsand trusses within the ditional bulkheads which intersectY the- íirst, and pontoon by which loadszare transmitted to- some complete the framework of the hullof: the dock. bulkheads and. througlrthem. to.- additi'onal; bulk The result is great strength and. a- large»saving> in heads. In the- embodiment: of thefínventionillusi structural> material.V The invention will be described in. connection 55 trated, the trusses and“ the`v various-- bulkheads 2,412,579 3 4 . are all connected together to form a unitary structure inside the hull. to 24 running from side to side, fore and aft of the middle of the pontoon; and bulkheads 25 and 26 extending from end to end. All bulkheads are A more speciñc object of the invention is to transmit deck load and buoyancy loads through rigidly united at the intersections. There is a parallel K frame trusses to bulkheads at the op buoyancy chamber in the pontoon between the posite ends of the trusses, and from these bulk bulkheads 22 and 23, but all of the other com heads to additional bulkheads within the pontoon partments formed within the hull by the bulk connected to and intersecting the first bulkheads. heads are preferably flooding compartments for A further feature of the construction is that sinking the dry dock. The location of the star the bulkheads are of a composite structure that 10 board wing wall section carried by the pontoon is thicker at the places where each bulkhead is indicated at 28, and of the port wing wall meets another bulkhead extending in a trans section by the broken lines 29. Framing trusses verse direction. This construction may comprise 30 extend parallel to the bulkheads 25 and 26 solid columns located where the planes of the on both sides of each, with extensions at intervals bulkheads intersect, the respective bulkheads be 15 beyond the bulkheads 2i and 24 running out to ing made up of sections connected with the solid the ends of the pontoon as seen in Figures 1 columns in such a way that the column Ais struc and 8. These trusses occupy most of the interior turally a part of the composite bulkheads. of hull, but are supplemented by a pair of trusses Dry dock pontoons made in accordance with 36a and extensions Sia (Figures 1 and 2) one at this invention have a number of bulkheads with 20 each of the longer sides of the pontoon. parallel trusses between and on each side of the The trusses 39 rigidly connect the transverse latter, bulkheads at the opposite ends of the bulkheads 2l and 22 in the port half of the trusses and under the wing wall sections on the pontoon and the bulkheads 23 and 2d in the star pontoon, and other trusses beyond the last named board half of the pontoon. Beyond the bulk bulkheads and less closely spaced. In this way 25 heads 2! and 24 the extensions are indicated at the greatest strength is concentrated under the 3l; these are not so close together as the trusses portion of the pontoon deck that supports the 3i). In the illustrated embodiment, every other ship, and less strength is needed adjacent the one of the trusses 36, with reference to either of ends of the pontoon where smaller stresses are the bulkheads 25 and 26, has an extension 3l. encountered. 30 Each of these trusses and extensions, and each Some features of the invention relate also to side truss 30a and its extension 3Ia form a single the connection of structural members 'and to continuous reinforcing truss member. The special joints that are particularly suitable for trusses 3!) may be continued across the buoyancy welded connections in ship construction and chamber at a suitable number of points, if de other objects, features and advantages of the sired; see the broken lines between the bulkheads invention will appear or be pointed out as the 22 and 23 in Figure 2. description proceeds. The bulkheads 25 and 26 are continuous and In the drawings, forming a part hereof, and traverse the width of the buoyancy chamber in which like reference characters designate cor~ between the bulkheads 22 and 23. Between the responding parts in all the views, latter bulkheads the hull is further reinforced Figure l is an enlarged sectional view taken on and braced as set forth below to give it the the line i-í of Figure 2; strength required. When the pontoon is assem Figure 2 is a diagrammatic, top plan view of a bled side by side with otheri pontoons to make pontoon hull for a multiple dry dock built in a dock, as set forth in my above-mentioned ap~ accordance with this invention; A4.5 lplication, with the bulkheads 2|, 22, 23 and 24 Figure 3 is a perspective view of jointing ele and the wing wall sections on each of the pon ments used at certain joints of the framing; toons all in alignment with these bulkheads and Figure 4 is an enlarged detail view illustrating wall sections of the other pontoons; and a ship the connection of some of the structural mem is moved in for repairs; the weight of the ship bers shown in Figure 1; 50 is borne upon keel blocks, indicated at K, Figure Figures 5 and 6 are two enlarged sectional views taken on the lines 5-5 and 6-6 respec tively, of Figure 2 showing the construction of the side trusses; ' Figure 7 is an enlarged, fragmentary perspec tive view taken in the vicinity of the line 'l ‘òf Figure 8; 1 2 on the floor or deck of the dock, in the middle; and bilge blocks. indicated at B set up near the .lines of the bulkheads 2l and 24. Each row of blocks bears about one-third of the total weight 55 of the vessel. ’ I shall first describe the outer trusses 33a and the extensions Sla within the pontoon at each Figure 8 is an enlarged, sectional view taken long side of the hull, parallel to the bulkheads on the line 3-8 of Figure 2 showing the struc 25 and 26, as shownin Figure 1. This sectional ture of the other trusses; 60 view illustrates deck plating 32 and a top beam Figure 9 is an enlarged. detail, perspective View 33, also parallel to the bulkheads 25 and 26; and taken on the line 9-9 of Figure 8; reinforcing elements 34 arranged crosswise there Figure 10 is a detail. perspective view showing of, The pontoon has bottom plating 36 with the connection of one of the bulkheads with the pontoon bottom; similar elements 31 and bottom chords or beams 38, extending in the same direction as beams 33. Figure 11 is an enlarged, ‘perspective view showing a portion of a bottom chord in the plane The beams 33 and 38 and the members 3!! and of the section line l I-II of Figure 8; 31 lie between the bulkheads 2i and 22, 23 and Figure 12 is an enlarged. sectional View taken 24. Between the extremities of the pontoon and on the line lZ-IZ of Figure 2; 70 the bulkheads 2l and 24‘these beams are ex Figure 13 is an enlarged sectional View taken tended in somewhat modified cross-sectional on the line l3-I3-of Figure 12; and ‘ form as shown at 33’ and 38' (Figure l) and the Figure 14 is an enlarged perspective viewtaken 'connecting reinforcing vrelements 34’ and 3?’ are Y on the section line I fl-l 4 of Figure 12. ’ in the same part of the pontoon. At the 'very A pontoon hull 2U (Figure 2) has bulkheads 2| ‘ ends, fore and aft, each of the beams 38' widens 2,412,578 »6 5 of the beam V38. The top braces >are similarly secured at ~their upper ends, Between each of the outer bulkheads 24 and 2|, and the ends of the pontoon, the two addi tional `K-frames along the `sides have their cen ters in similar uprights; and are attached to the beams 33’ and 38' in the saine way; :except that the diagonal braces of the first are made fast at their ends near the deck bottom beam extensions to the upright `reiirforceinents 33' upon said bulkheads.- The channel beams @2 extend outl into a broad web and runs up to the deck, as shown in Figure 1 at 38a. Along these sides, further, between bulkheads 2| and 22, 23 and 24, and beyond the bulkheads 2| and'24, uprights 33 unite the upper beams 33 and their extensions 33'; at their junctions with the upper members 34 and 3-’t’; to the lower ‘beams 33 and t8’ at their points of intersection with the lower members 3l and 3l'. Alternate uprights 33, which are I-shaped in cross-section, of trusses 30a and all uprights in extensions Stu are connected with the top beam 33 and 33’ and lower beams 38 and 38’ nby diagonal braces 59. These braces 4Q are made fast to the uprights 39, at points midway between the upper and lower ends thereof, by `gusset plates 4|, to form frames that are K-shaped. All >of the uprights 39 are connected at the same points with hori zontal braces or channel .beams 42, which join >the K-frames of each truss at their centers. 20 vBeams 42 are also affixed to the bulkhead at the buoyancy chamber and to a plate 33h at the edge of the web 38a. There are horizontal stiifening members or ribs 44 secured to the bulkheads 2|, 22, 2?, andZll. A rectangular coaming 4t is secured on the deck of the pontoon at each end and serves as the support for the section of the wing wall which is there mounted on the pontoon. Each coaming extends across the pontoon’s full width and its two long sides lie in approximately the plane of the outermost uprights Y33, and the plane of the nearest bulkhead 2| or 24. . On one face of each of the bulkheads 22 and 23 at each side of the middle of the pontoon are vertical .stilïening ribs 23a, T-sha-ped in cross section, presented to the bulkheads 2| and 24 and anchoring the adjacent ends of the channel from said bulkheads through these two K-frames also and are joined, as already stated, to the widened portions 38a of the beams at the ends of the pontoon. These beams are pieced at the bulkheads 2| and 2Q, and secin'eiy welded thereto. Thus a complete truss or girder made up of K-frames extends ¿from each bulkhead i2 and 23 out past the bulkheads 2| or 24 to the two ends of the pontoon along either side. Figure 5 shows the design and arrangement of these trusses Sla along the sides, beyond the longitudinal bulkhead 24; the plan beyond the bulkhead 2| being the same. This View also f depicts the longer bulkheads 25 and 26 and with stiffening ribs «lil extending horizontally along same andthe intersecting bulkheads. Manholes such as appear at 5| .are provided near the lower end of the bulkheads 2| and 24 for access from one compartment to another. When the dry dock pontoon is in use, each manhole 5| is prefer ably closed by a plate, and each of the compart ments is provided with its own piping for flood ing or pumping water from the compartment. Similar manholes are provided in the other bulk heads wherever needed. The construction of the trusses Sil and the ex tensions 3! is best illustrated in Figures 5, 6 and 8. The trusses 3l! include horizontal upper chord bottom beams 33 and 38. At their junction with to members made of beams 52 and lower chord members embracing beams 53, connected togeth the latter are gussets ¿lila to which the lower ends er by upright beams .or columns 54 and diagonal of the adjacent diagonal ,braces ¿til are welded. braces 5E. Each deck chord consists of two par Between each of the bulkheads 22 and 23 and allel beams 52, each bottom chord of similar the outer ones 2| yand 24, the uprights '3S and beams Y53, extending from the bulkheads 22 and braces 4B are illustrated as providing four K 23 `_out to the bulkheads 2| and 24. They lie be frames, starting at the former and ending at the tween and outside of the 'bulkheads 25 and 26. latter; and two more such frames beyond bulg `beams Y42. These ribs are welded-to the deck and heads welded 2!to and the faces 24. All of Athe diagonm plates braces ¿5i `which are m tum welded along one edge to the edges oi’ The vdiagonal braces 55 comprise opposed angle bars ¿connected together by batteri plates 5l, The trusses all have uprights 54 that are I-shaped in the ñanges or" uprights 3s; and the >outer faces 50 cross section. A section through the trusses 30 is shown in Figure 6 to indicate how the uprights of the bulkheads 2i and are also reinforced V54 are inserted at their ends between the beams in the planes of the trusses 3io by `Vertical ribs 52 and 53 and united thereto; the braces 53 hav 3.9’ comprising angle beams welded along `their ing their ends attached to these chords in the outer edges, as shown in Figure l. same manner. Figure 4 shows the connection between the The braces 56 are omitted from Figure 6 for the diagonal ’braces t@ and the bea-ms 3,3 and .3S and sake of clearness. But Figure '7 illustrates the their angle extensions. member andEach attached vdiagonal to the brace topdo ofis *ne manner in which the diagonal braces 56 of the trusses 3b are connected with the uprights 54 at beam shown for example at with one its flanges Vertical and in the vertical plane of the 60 approximately the mid-points of the latter, by means of gusset plates 53 welded to the flanges of the braces and uprights. The trusses 30 are with web flange of the of the the. top beam. brace of theThe rests beam, brace onand thetopis the bevelleo. other oi theorb o. cross-connected with one another by channel beams 43, welded to the outside surfaces of the An extension ¿it is welded to the web and , ñanges of the uprights 54, with reinforcing plates ñange flange of the the beam brace and in such to the a >position end of the that it 59 welded to the inside faces of the flanges and to the websof the uprights 51E in such a position as to form, in effect, a continuation of the sides side flange of the diagonal brace 4i). of the channel beams 43. This construction gives A splice plate 45 has its upper portion welded edgewise to the outside cr back ei the vertical 70 the cross beams 43 the same strength as if they were continuous, and at the >saine time does not flange of each diagonal brace 40, and its lower weaken the uprights 54 by cutting through their portion welded to the remaining face of the nanges. The beams 43 join the centers of the vertical web of the beam 33. The `cut-out or K-framesfrom the channel beam 42 on one »side recessed portions ¿El l(Figure 3) of the parts ci of the pontoon to the channel 42 on the other and and 48 are for fitting the edges of the flange forms, in eii’ect, a continuation of the other or 2,412,578 8 cept adjacent the bulkheads 2| and 24) are also are rigid with the bulkheads 25 and 26 where they connect with same. These beams reduce the free, e'lîective span of all the uprights in the trusses by half, and reduces the amount of material oth~ erwise needed. The construction of the truss extensions 3| is similar to that of the trusses 36. Figures 1 and 6 show the K-trusses 36 arranged reinforced by similar plates 56h at their junc tions with upper and lower beams 52’ and 53'. The braces 56’ of the extensions 3| nearest to the bulkheads named are secured above and below with their ends partly between the beams 52' and relatively close together between bulkheads 2| and 22, 23 and 24; and Figure 5 shows how the adjacent faces of these bulkheads and uniting the deck beams 52’ and bottom beams 53'. The truss extensions 3| are farther apart in the spaces between the bulkheads 2| and 24 and the ends of the pontoon. On either side of each of the bulk heads 25 and 26, the extensions 3| coincide with uprights 54 and braces 56 as stated above, are and are continuations of every second truss 36. In Figure 5 the positions of the trusses 30 not extended are indicated by the plates 58. .Figure 9 shows the bottom chord or beam struc ture of truss 36, between the bulkheads 2| and 22, 23 and 24. Parallel structural members, pref erably T-sections 6|, with the bottom plates 36 of the pontoon welded to them, have the webs ex tending upward, and angle bars 62 are welded to 53', and reinforcing ribs 54a, attached to the enveloped at their ends by the beams 52 and 53 and welded to the inner face of the bars 6| and 62. The uprights 54’ of the trusses 3| are welded at their ends to the beams 52' and 53’ at the flanges thereof; and the angle-bar braces 56’ are welded to the inside faces of these beams, the same as the braces 55. The terminal K frames of trusses 3| at bow and stern, comprising diagonal braces 56' joined at deck and bottom to beams 52’ and 53’ are secured ed by batten plates 63 at spaced points along their length to give a chord that is compound in at their adjacent ends to gussets 58' on partitions or auxiliary bulkheads 59 extending across the extremities of the pontoon. The beams 52’ and 53’ terminate at these partitions and the re maining space is braced.and divided as may be necessary. Figure 13 illustrates the manner in which the structure. There are limber holes 64 along the lengths of the T-sections 6| for the passage of six bulkheads are connected with one another. Each of the bulkheads 25 (and 26) is of com water. The top chord with beams 52 is similar. posite construction and comprises plates or webs 68 between bulkheads 2| and 22, 23 and 24, con nected at one end with a solid column 69. Each of the bulkheads 25 and 26 also includes plates 68’ beyond bulkheads 2| and 24, connected to the other sides of the solid columns 69. Such a column 69 is located at each junction of the bulkheads 25 and 25 with the bulkheads 2| and the upper edges of the webs of the T-sections 6|, the remaining flanges of the angle bars ex tending outward. The angle bars 62 are connect The deck and bottom beams 52 and 53 are cross braced at the requisite number of points by ribs 34 and 31 respectively, rigidly attached to said beams. Figure 10 shows the union of the bulkheads " and the pontoon deck and bottom plating. 'I'he bottom edge, for example, of the plating of the bulkhead 25 is shown welded to the upstanding 24. The bulkheads 2| and 24 are made up of plates or webs welded to opposite sides of the ed to the ilange of this beam. All the bulkheads - i. column 69. may similarly be connected with the top and bot Each column 69 is considerably thicker than tom plating of the pontoon hull. the plates 66 but is preferably provided with ver Figure l1 shows the construction of the bottom tical stiiîening ribs 'lil comprising T-sections chord of each truss extension 3| near the ends of welded to one side. The portions of the bulk the hull, at the places where it is intersected by " heads 25 and 26 that extend through the buoyancy bottom stiffening ribs 31a. These ribs are pref chamber are made of plates 'll much thicker than erably constructed with recesses along their lower the plates 68 in order to provide greater strength edges, to which are welded the bottom plates 35. between the bulkheads 22 and 23, which are sub The recessed or serrated edges also allow pas ject to considerable pressure when the pontoon sage of water. The bottom chord construction ' is flooded. For clearness the parts 69 and 'I9 are of Figure l1 involving the parallel beams 53’ dif omitted in Figure 8. fers from Figure 9 in that ñat bars 6| ' take the Figure 14 shows the construction by which the place of the T-sections 6|, for in the truss ex bulkheads 25 and 26 are reinforced. In addition tensions 3| less strength is required. The beams to the horizontal ribs 44 with serrated edges 53' of these extensions are thus cross-braced by welded to the face of the bulkheads, there are ribs 37a fastened thereto at various points. upright flat bars or plates 'I3 welded to the bulk Each upper chord of the truss extensions 3| heads and the outer edge of each bar or plate comprises similar parallel beams 52’ between the 13 is stiiîened by a T-bar 14 welded to the edge bulkheads 2| and 24 and the ends of the pontoon of plate 13. The stiiîening ribs 44 extend of slightly less height than the beams 52. These through openings in the plates 13. For the sake beams 52’ are also cross-connected along their of clearness, these ribs 44 have not been shown edges, and~ cross ribs 34’ of any suitable size and in Figure 8. shape are attached between these beams. The horizontal channel beams 43 uniting the In the trusses 3G, the bottom ends of thelower K-frames of trusses 3D and 36a and extensions braces 56 are anchored further between gusset 3| and 3|a are also attached to the bulkheads 25 plates 56a and 56o adjacent the lower beams 53, and 26 in sections; one length having its end and welded to these plates. Reinforcing ribs 23' welded to the flange of the T-bar 14 and another on the faces of the bulkhead 23 (and 22) con length being connected with the other side of the nect the deck beams 52 to the bottom beams 53, bulkhead 25 by a gusset plate l5. There are and the plates 56a unite these ribs to the beams plates or bars 'I1 between the ñanges of the T 53. The plates 55h are attached to the beams bars and bulkheads that form in effect continua 53 and lower ends of uprights 55, and the lower tion of the channel beams 43. ' ' ' ends of adjacent braces 56 and uprights 54 are The construction at the sides of the pontoon between them and beams 53 and attached to between the outermost trusses 30a and 3|a is same. The braces 56’ of the extensions 3| (ex indicated in Figures 5 and 6 but need not be web of a T beam 66. The bottom plating is weld L! 10 detailed herein. These parts are reinforced and transverse, bulkheads running in the sal-ne- direc',v divided between the sides and the uprights 33; tion as bulkheads 25 and 26 are added in such so as to support the outside plating and close the pontoon, but the load stresses fall upon the trusses number that in a structure of the dimensions only. Ul All of the connections described herein are welded, but the invention is not limited to welded joints and seams and some members can be used with rivets or other fastenings. Various changes and modiñcations can be made and some ofthe features oi the invention can be used without others. In the trusses 32a and 3m the uprights Stall specified above, they will be only 8 feet apart. The» replacement of most of these by K-trusses aflfords a great saving in steel, without loss of strength. The trusses make the bulkheads 2l to 2t rigid; these in turn, especially Vin combination with the» cross beams d3 uniting the K-irames of the different trusses, stiften the bulkheads 25 and 25 so as toobviate all risk of buckling, warping ory other distortion. These cross beams also brace the side plating. to the extent demanded against the outside pressure of the water; the bulkheads have the same dimensions; and so do the upper 25 and 25 and channel beams 52, and trusses 3l braces llü. The lower braces ¿il are a bit lighter and Sig, also having the like result with respect except the one nearest the end, which is of the to the outer plating at the ends. The general same size as the top braces. rï‘he lower braces eiieet is to make the bulkhead, framework and are stressed more evenly by the buoyancy load; deck and'bottom plating so rigid that the bulk but at the outer end of the extension 31a the upward bending moment is greatest. Hence the 20 headsvirtually become girders; with the deck and bottom plating serving as the flanges, and the lower brace lli) at this point should be somewhat stronger. As for the trusses 3.5, and 3i the uprights 5,4 and 5d’ are all a bit lighter than the upright/s 39, but those of the extensions 3l are heavier and » stronger than in the trusses 3Q. The êí-iraines oi these trusses 3€! and the extensions Si are also lighter than in the trusses 35a and Sia, but are so designed that the braces 5t’ at the ends of the pontoon can well resist the upward bending i moment due to buoyancy; and the braces in the extensions Sia at the bulkheads 2l and 26 are bulkheads themselves as the Webs; and the cross, beams d3 have the additional utility of so bracing the K-frames at the centers that the spans o_f the uprights 3.9, 5d and 54’ is only half their length. IThis too, increases thev strength and contributes to the general saving in materials oi construction. As indicated in Figures 8 and 12, only the ex, tension Si in the very middle of the pontoon will have five i<~frames Those at each side will have ewer because the hull is ship-shaped, as set forth in my co-pending application for patent above mentioned. rThe transverse end bulkheads 59 are suited to the weight loads of ship and wing wall section above and buoyancy below. The upper of less height at the ends where they are attached braces in the trusses 30 between the bulkheads to» the bulkheads 25 and 25 (Figure 12). The 2i and 22, 23 and 2G are lighter than in the lower edges of these bulkheads curve upward near trusses 3Go; and the remaining braces, upper and the extremities as Figures 8 and l2 illustrate. lower, in both trusses 35 and extensions 3l, espeBut the four cross-beams 43 of the extensions 3l cially the upper and lower braces in the three remaining K-frames of the latter between the 40 extend all the way across the ends from one side ` to the other. K-frames at the ends thereof and bulkheads 2l The deck and bottom plating reinforcing ribs, and 24 are lighter still than in extensions Bla beams, uprights, braces, bulkheads and all other because the stresses are less and those due to members, are securely welded in their various the buoyancy loads are evenly distributed. parts and in their respective positions to make The central buoyancy chamber between the the pontoon as strong as possible at all points. bulkheads 22 and 23, has a relatively light central rîhe construction described is well adapted to at bulkhead It and is traversed by the two long tain all the objects of the invention. bulkheads 25 and 26. This chamber also con Having described my invention, what I believe tains room for machinery, crew’s quarters, stor to be new and desire to secure and protect by age and fuel space, etc. Between the bulkheads Letters Patent of the United States is: 22 and 23 are reinforcing members 52A which are 1. In a hull for a dry dock the combination of in line with the chords containing the members trusses, each of which has a deck beam, a bottom 52 and 52'; thus forming composite beams that beam, uprights connecting said beams, braces are continuous from end to end of the hull. The f uniting said beams to points between the ends of waist of the hull containing this chamber is iur the uprights, and beams uni-ting said trusses to ther reinforced by iiooring and other members as one another at said points. required. 2. A hull for a dry dock pontoon containing The unit stresses due to buoyancy load are re trusses, each of which includes a deck beam, a duced because the pontoon is lengthened beyond the wing wall locations. At the same time a more 60 bottom beam, uprights between the beams, diag eñîcient beam effect is produced- by the tapering onal braces connecting the uprights at points ends of the hull. It will be noted that the trusses Sû-Sßa are intermediate their upper and lower ends to said beams, a beam uniting said uprights of each truss at said points, and cross-beams connecting the .trusses together at said points. 3. A hull for a dry dock pontoon containing needed; and in a pontoon 250 feet long by 80 longitudinal bulkheads, transverse bulkheads in feet beam, for example, these bulkheads will be tersecting said longitudinal bulkheads adjacent over 30 feet apart. The trusses stiften the other the ends of said pontoon, vertical columns at bulkheads and enable them to withstand the weight of ship and wing wall sections. Both 70 the intersections, said columns being of greater thickness than .the bulkheads and said bulkheads weight loads and buoyancy loads are transmitted being made up of sections that have their ends by the trusses to the bulkheads 2l, 22, 23 and 24; permanently connected with said columns and through these to the bulkheads 25 and 26. throughout the length of the latter, and a trans In the usual design of dry dock pontoon, with a single central bulkhead parallel to the side walls, 75 verse bulkhead at each side of the middle of the all relatively close together. Hence only two bulkheads 25 and 25 running from end to end are 2,412,578 11 12 pontoon intersecting the longitudinal bulkheads, beams to connect the centers of the K-frames of the trusses to .the additional bulkheads. the latter being of greater thickness between the 9. In a hull for a dry dock pontoon, the com last-named transverse bulkheads. bination of parallel top and bottom beams ar 4. A hull for a dry dock pontoon having inter ranged in pairs, bottom plates attached to the secting, rigidly connected bulkheads and .trusses lower edges of said bottom beams, ythe upper edges comprising K-frames crossing some of said bulk of said plates having out-turned iianges, stiffen heads and fixed thereto, said trusses being sub ing ribs passing through said beams, transverse stantially parallel to the remaining bulkheads, battens secured to said flanges, uprights secured and connected transversely to one another adja 10 to the top and bottom beams, and braces secured cent the midpoints of said frames. to the uprights and the opposed faces of said 5. A hull for a dry dock pontoon, comprising a pairs of beams. pair of bulkheads between each end and the mid 10. A hull for a dry dock pontoon, having inside dle of the hull, additional bulkheads extending .trusses extending side by side, from the middle from end to end intersecting and united with the towards the ends of said hull, bulkheads spaced aforesaid bulkheads, and trusses 4parallel with from the ends of the pontoon and intersected said additional bulkheads, said trusses uniting the by said trusses, some of said trusses being shorter members of each pair of Ithe aforesaid bulkheads, and some of said trusses being extended beyond and some longer than the remainder, the longer them towards each adjacent end of the hull. projecting beyond said bulkheads, the shorter 6. The hull according .to claim 5, having cross .trusses terminating at said bulkheads and short beams at predetermined points connecting said of said ends. 11. A hull for a dry dock pontoon, having trusses and said additional bulkheads. 7. A hull for a dry dock pontoon having a pair trusses within the hull, said trusses extending of bulkheads between the middle and each end, side by side from the middle towards the ends, additional bulkheads extending from end lto end bulkheads spaced from the ends of the pontoon and intersecting and united with both pairs of and intersected by said trusses, some of said trusses being shorter and some longer than the bulkheads, trusses comprising K-frames between and along the outer sides of the additional bulk remainder, the longer projecting past said bulk heads, said trusses connecting the aforesaid bulk heads, the shorter ones terminating at said bulk heads of each pair together, some of said Itrusses 30 heads and short of said ends, and the longer trusses having relatively heavy portions at said extending out lto the adjacent ends, `and a beam ends to resist upward bending moments. connecting the K-frames of 'some of the trusses together at the centers of the latter. 8. The hull according .to claiml 7, having cross FREDERIC R. HARRIS.