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Патент USA US2412578

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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
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Dec. 17, 1946.
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F, R, HARRls
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2,412,578
DRYDOCK PONTOON CONSTRUCTION
Filed Aug. '7, 1943
5 sheets-sheet 4
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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.
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