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Nov. 13, 1962
Filed Aug. 27, 1959
6 Sheets-Sheet l
Nov. 13, 1962
Filed Aug. 27, 1959
6 Sheets-Sheet 2
Nov', 13, 1962
6 Sheets-Sheet S
Filed Aug. 27, 1959
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Nov. 13, 1962
Filed Aug. 27, 1959
6 Sheets-Sheet 4
Nov. 13, 1962
Filed Aug. 27, 1959
6 Sheets-Sheet 5
Nov.~ 13, 1962
Filed Aug. 27, 1959
6 Sheets-Sheet 6
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Patented Nov. i3., 1962
opposite in sense to the force acting on the surface ship
of the same length heading into the same waves at the
lilarold Boericke, Jr., 1122 16th St. NW.,
Washington, D.C.
Filed Aug. 27, 1959, Ser. No. 836,556
5 Claims. (Cl. 114-57)
(Grmted under Title 35, US. Code (1952), sec. 266)
The invention described herein may be manufactured
and used by or for the Government of the United States
of America for governmental purposes without payment
of any royalties thereon or therefor.
The present invention relates to sub-surface craft com
bining the high top speed and ygood propulsive qualities of a
submerged submarine with the structural and operational
simplicity of a surface ship.
It is well known in naval architecture that _the speed
of a surface ship is greatly limited by wave formation
and resistance resulting from thesewaves. As the speed
o-f a ship is increased its Fronde number increases, this
same speed.
This distinction is important.
, Y
It must tbe realized that the submarine has complica
tions which make it the most expensive type of vessel
to build Iand the most complicated type to operate. The
conventional submarine has a pressure hull, ballast tanks,
trim tanks, negative tanks, diving planes, and must have
a system of propulsion which will enable it to stay below
0 the surface for an extended period of time.
Consider 4a surface ship attached to the top of a sub
marine operating in head seas.
The wave forces on the
two would be opposite in sense, _and tend to cancel each
other out. The present invention is essentially a sur
15 face ship attached to the top of the submarine. Theo
retically by varying the proportionate sizes of the two
it would 'be possible to get a combination having a zero
pitching motion. A conventional surface ship operating
in ywaves longer than its own length will heave at an
In waves
number lbeing a relationship `dependen-t upon ship’s speed.
20 amplitude about equal to the wave height.
At Froude numbers of 0.3 and greater, wave resistance
increases at a very fast rate. This phenomenon limits
on the relative length of ship and wave.
shorter than its own length it will heave less, depending
Because most
of its ‘buoyancy is concentrated near the surface, the
conventional surface ship is excited by the orbital mo
a maximum Froude number of about 0.5.
It is also 'well known that such surface _ships must .slow 25 tion of the wave at its maximum amplitude; that is, near
the surface; it will heave a maximum amount. This
down greatly in heavy weather and that in gales, sur
applies particularly to heaving in seas of lengths of l to
face ships Imust usually stop or drift with the waves
5 tim-es the ship’s length.
merely to survive. It is also well known that the ef
The submarine operating near the surface, will heave
lfects of rough seas vary both the velocities -and the di
the speed of conventional full bodied surface vessels to
rection of water flow into the propellers. »Another ef
fect encountered in the operation of a conventional ship
in rough seas in the slamming of the ship’s bottom on
the waves. The ship tends to dive and leap in a Seaway
causing water on the deck, and high pressures from the
slamming on the ship’s bottom, which tend to cause great
structural strains on the shi-p’s hull.
It is also well known in naval architecture that a sub
an amount depending lhow near it is `to the surface. A_s
the orbital motion of the lwave decreases rapidly with
depth, the heaving motion Iwill also become less to the
same degree.
-A sub-surface ship, being configured much like a sub
marine operating near the surface, will have .similar heav
ing characteristics.
It will heave much less than a sur
face ship of the same length operating through the same
marine, operating at a depth below the surface of 3
sea-way at the same speed.
sistance being frictional and eddy making resistance. Op
considerations have ¿also been a `factor in lengthening
Seakeeping qualities are one of the main reasons for
times the `diameter of the hull or greater, experiences a 40
many surface vessels being as large as they are and speed
negligibly small wave resistance; nearly all of its re
eration at depths of more than 3 diameters eliminates a
crucially important limitation to the speed experienced
many surface vessels.
This invention makes size a less
compelling reason fo-r speed and seaworthiness. The sub
surface ship of this invention provides a means of meet
by all of the conventional surface ships since the fric 45
ing mounting performance requirements lwith smaller and
tional 'and eddy making resistance of a submarine in
creases Iwith speed ,at a very much slower rate.
fore the top speed of a submerged submarine is poten
tially much higher than that of the conventional full
cheaper ships.
It is therefore an object of the present invention to
provide a vessel having better sea-keeping qualities than
bodied surface ship of the same length and immersed 50 conventional craft.
Another object is to provide a vessel which will reach
a top speed in smooth water which is considerably higher
It is further well known in naval architecture that
than conventionally shaped full bodied surface ships of
only a negligibly small motion caused by ocean waves is
the same length and immersed volume.
experienced by a submerged submarine operating at a
A further object of the present invention is to pro
depth below the water surface of 3 diameters or greater. 55
vide a craft which will exhibit pitching and heaving mo
Operation at these depths avoids the critically important
tion an order of magnitude lower than `existing dis
limitation to speed of conventional surface ships yoperat
placement type surface vessels ofthe same length.
ing in rough seas. The all-weathercapabilit-y of the sub
Still another object is the provision of the craft ,on
marine therefore is absolute, compared with the severely
limited capability of surface ships.
60 which the propeller axis is suñiciently far below the water
surface so -as to experience a minimum disturbing effect
The submarine operating near the surface, however,
begins to be effected by waves depending on its nearness
to the surface. An _important feature of this operation
from the excitation of waves.
The exact nature of this invention as well as other
is the mode of response to the waves. When a ysub
marine operating near the surface enters an oncoming
objects and advantages thereof will be readily apparent
train of waves, and as the wave crest passes over the
bow, the additional weight of the water in the wavecrest
to the annexed drawings in which:
FIG. 1 is a side elevational View of a preferred ern
causes a downward force on the bow.
bodiment of this invention;
This force on
from consideration of the following specification related
FIG. 2
FIG. 3
sense to that of the wave surface, ‘that is when the sur 70
face is up, >the force is down. Thus, the wave force act
FIG. 4
ing on a submarine operating when near the surface is
the submarine operating near the surface is opposite in
is a partial stern view of the vessel of FIG. l;
is a partial bow View of the vessel of FIG. l;
is a series of vertical cross sections of the em
shown in FIG. l;
FIG. 5 is a series of horizontal cross-sections of the
the center of volume of the body 47 and the center of
volume of the underwater protion of the island 46.
In a ship of this type, its machinery, fuel and payload
are enclosed in body 41; crew’s accomodations and access
to the island, and control and communications in the
small superstructure 48.
FIGS. 6-10 show a modified type of subsurface craft
having certain features of form which improve its motion
and seakeeping properties as well as provide certain prac
embodiment shown in FIG. 1;
FIG. 6 is a side elevational view of another embodi
ment of this invention;
FIG. 7 is a partial stern view of the embodiment shown
in FIG. 6;
_ FIG. 8 is a partial bow view of the embodiment shown
in FIG. 6;
FIG. 9 is a series of vertical cross-sections of the em
bodiment Yshown in FIG. 6;
tical features. Sections B’ through J', FIG. 9, show body
51 which is elliptical in cross-sections with its major axis
located horizontally. By this shape more immersed
volume can be concentrated further away from the water
FIG.l l0 isa series of _horizontal cross-sections of the
embodiment shown in FIG. 6;
FIG. 11 is a side elevational view of another embodi
ment in this invention; _
surface at a given draft than with a hull whose body has
a substantially circular cross-section as shown in FIGS.
The single island is wider at the water line than it is
at the junction of the body as shown in sections B’
through F’ in FIG. 9. This is combined with a reserve
~ FIG.l 12_i_s a partial stern View of the embodiment
shown in FIG. 11;
, FIG. 1,3 is a partial bow View of the embodiment shown
in FIG. 11;
, FIG. 14 is a series of vertical cross-sections of the em
bodiment shown in FIG. 11;
FIG. 15 is a series of horizontal cross-sections of the
embodiment shown in FIG. 11;
FIG. 16 is a side elevational view of still another em
bodiment of this invention;
buoyancy having much flare, which is shaped broad on
deck and which projects forward and forms a bow over
hang as can be seen in FIG. 6 and FIG. 9A'. In addi
tion, the reserve buoyancy has a longitudinal ridge 53,
termed a chine, located above the waterline to control
FIG. 17 is a partial stern view of the embodiment 25 and suppress the bow wave and provide ample reserve
shown in FIG. 16;
buoyancy near the deck. The flaring shape of the island
and of the reserve buoyancy forward provides a shape
in FIG. 16;
which prevents diving in a following sea, suppresses which
FIG. 19 is a top View of the embodiment shown in
would otherwise be a very high bow wave, and keeps
FIG. 16;
30 decks reasonably dry in a head sea. In addition the for
FIG. 20 is a series of vertical cross-sections of the
ward projection of the bow provides a hoisting point for
embodiment shown in FIG. 16;
the anchor chain to swing anchors clear of the obstruct
FIG. 21 is a side elevational View of a fifth embodi
ing underwater portions of the hull. A feature which
ment of this invention;
will reduce the motion is the actuated anti-rolling fin 55
FIG. 22 is a partial stern view of the embodiment 35 which counteracts roll. The rudder 43 is all movable,
shown in FIG. 21;
for maximum effectiveness, and is located on the after
FIG. 23 is a partial bow View of the embodiment
part of the body, forward of the propeller 42, and is
shown in FIG. 21;
positioned far enough astern of the island to receive
FIG. 24 is a series of vertical cross-sections of the
nearly unobstructed water for effective turning. Also
embodiment shown in FIG. 2l;
notable on this embodiment are stern planes 54 which
FIG. 25 is a series of horizontal cross-sections of the
give an additional measure of pitching control.
embodiment shown in FIG. 21;
FIGS. 11 through 13 show another type of sub-surface
FIG. 26 is a side elevational View of still another em
craft in accordance with this invention having twin is
FIG. 18 is a partial bow view of the embodiment shown
bodiment of this invention;
FIG. 27 is a partial stern view of the embodiment
shown in FIG. 26;
FIG. 28 is a partial bow view of the embodiment
shown in FIG. 26;
FIG. 29 shows a series of vertical cross-sections of
the embodiment shown in FIG. 26; and
FIG. 30 shows a series of horizontal cross-sections of
the embodiment shown in FIG. 26.
Referring now to the drawings wherein like reference
characters designate like or corresponding parts through
out the several Views there is shown in FIG. l which
illustrates a preferred embodiment, an underwater hull
41, to which is connected an island 44. Hull 41 is a
body which is essentially an elongated streamlined body
lands 57 and 58. The twin islands have a smaller cross
u section at the water line than the single island of FIGS.
1 or 6, therefore the wave making resistance is smaller
and the excitation from waves is less. This results in a
higher speed and less motion than is possible for a single
island craft. The body or underwater hull 50 of this
embodiment is elliptical in cross-section, again placing a
maximum amount of immersed volume as far away from
the surface as possible for a given draft.
The two is
-lands are located as far apart as practical in order to
provide as much longitudinal stability as possible with
the minimum water plane area dictated by this type of
design. As can be seen from the cross-sections A2, B2,
and H2 in FIG. 14 the islands 57 and 58 have a carefully
tapered junction with body 50 for maximum strength
of revolution of circular cross-sections as shown in A-H
and a minimum waterline area for minimum wave re
in FIG. 4.
sistance. Islands 57 and 58 both have longitudinal
The island 44 is, in general, almost as narrow near
chines 53 which are utilized to inhibit spouting of water
the waterline as where it joins the body41, in order to
upward along the island and to provide su?icient width
minimize wave resistance. Rudder 43 is an extension
for a suitable amount of reserve buoyancy. In order to
of island 44. Propeller 42 is located at the stern end
maximize reserve buoyancy, it has been found expedient
to blunt the trailing edges as shown in FIG. 15 sections I,
of the body 41, thereby causing a substantially circum
on both islands into a tiat end which is commonly called
ferentially uniform wake distribution which results in a
a transom. The forward island has a larger volume
high propulsive eiiiciency. The circular cross-sections
both above and below the water line than the after island,
of the hull combined with the vertical sides of the island
represent a form of nearly minimum wetted surface con- " causing the resultant centers of volume of the islands
46 and 45 below the water line W.L. and above it re
sistent with the features of form which are proportioned
spectively, to be forward of the center of volume 47 of
to reduce wave drag. Above the water line W.L., the
the body, which results in a favorable type of pitching
island 44 flares outwardly from the vertical axis and also
response. Auxiliary planes 54 and 56, at the stern and
extends in a forward direction resulting in a center of
bow respectively give a measure of added control under
volume of the reserve buoyancy 45 which is forward of
severe conditions.
The island 67 extends for nearly the full length of the
craft and has a water plane of sufficient length to pro
vide pitching control in the waves without the need for
external tins. This island contains living quarters and
of this form has its machinery, fuel, payload, and prin
cipal living quarters located in body Si); control, com CII consumable stores. A small raised superstructure 43
maintains control and communications spaces.
munications, and access located in the forward island 53;
Displacement changes from one draft to the other are
and machinery air supply and access enclosed in after is
accomplished by variable water ballast tanks ‘68 and 69
land 57.
located in the ends of the ship as seen in FIGS. 2l and
FlGS. 16-20 describe a three island sub-surface craft
25. When these tanks are empty the ship floats higi in
with island 6l located on the center line aft, and islands
the water in the shallow draft condition, but as water is
62 and 63 located side-by-side forward and emerging at
pumped into the ballast tanks 63 and 69 by pumps 72 the
substantially right angles from an elliptical shaped under~
ship sinks to a new deeper waterline. Alternatively to
water hull 65. The transverse separation of the forward
increase the immersion more quickly, the water may be
islands provides suliicient transverse statical stability so
allowed to gush into the tanks by means of flood holes
that the center of gravity of the craft can be higher than
The rudder 43 is attached to the after island 57 and
faired in with it for a minimum of drag. Propeller 42
is mounted on the aftermost portion of body Sli. A ship
73 and vent valves 74.
Another embodiment of the varia-ble draft ship is
faces 59 behind each bow island which assist in mainshown in FIGS. 26«30. As contrasted with the previous
taining an exact draft under rough sea conditions, some
figures, it has a single island '76 with minimum size for
what analagous to the bow diving planes of a submarine.
The shape of the islands is characterized by the same 20 the purpose of minimizing motion at the greater draft,
a minimum displacement change when changing draft,
features as those of the twin island craft.
and a maximum top speed at the deep immersion. The
The two islands are located as far apart as practicable
body 75 has a spindle shaped hull slightly flattened on
in order to provide as much longitudinal metacentric
top to provide a water plane sufficiently wide to give ade
stability as possible with the minimum water plane dic
quate metacentric stability at the minimum immersion.
tated by the design. The forward islands connect with
The island 76 is of relatively short length and of great
the body at right angles with the surface of the body
ñneness ratio for minimum wave resistance and is lo
thereby minimizing interference drag. The islands then
in a twin island craft and in addition carry movable sur
bend into a straight upward direction piercing the surface
cated as far forward as possible for the reasons outlined
and at a considerable distance above the surface are
Pitching control is achieved mainly by changing buoy
joined together by a horizontal platform 6e. if desired,
the platform '64 could be extended and join the tops of all
ancy of the island ’76, therefore the size of water planes
54 and 56 is reduced to a minimum. The buoyancy
change of island '76 is, in eifect, an apparatus which
senses the height of oncoming waves to maintain pitch
ing control. Auxiliary control planes 56, located at the
bow, and control planes 54, at the stern, assist in provid~
three islands. The after island is shaped the same as
its counterpart in the twin island sub-surface craft de
scribed above.
ln this configuration machinery, payload and fuel are
included in body `65; control, communications, and living
ing longitudinal trim control.
quarters are in platform tid; access is provided by for
ward islands 6l and 63, and the air supply and access
for the machinery by the after island 6l.
Chines 53 are again provided in this embodiment for
the purposes described in connection with the other em
Ballast tanks such as were provided in the previous
embodiment are used to vary the displacement. Because
of the volume of the hull between the largest and the
smallest immersions is smaller than that of the previous
embodiment shown in FlGS. 21-25, the sizes of the nec
essary ballast tanks 63 and 69 are correspondingly
Also included in this embodiment are aux~
iliary movable stabilizing planes at the stern 54 for added
smaller, providing more usable space in the ship.
Also, the island '7d is smaller than the previous em
longitudinal stability control.
The embodiments described thus far have a relatively
deep draft at all times, which due to harbor depth restric
tions, currently about 35 feet, limit their use to ships of
bodiment; a lower wave resistance at maximum immer
sion will be experienced resulting in a higher top speed
for the same power. ln this craft the prime mover, the
payload, fuel, and most of the crew accommodations are
relatively small size, approximately 7000 displacement
tons and less.
in the body 75 and the control and communication spaces
FlGS. 2l through 25 show a type of vessel in which
are located in the flared portion at the top of the island.
the draft may be varied between large limits. The let 50
The rudder of this embodiment is secured to the small
ters WL. denote the normal operating waterline of the
cross-section of the hull at the stern and is divided into
ship, while the letters W.L.D. denote the water line used
two sections 43 and ‘1l-3a to give adequate steering.
when the ship is in shallow water or being docked. The
Propeller A4t2 is placed rearward of the rudders a suffi
draft may be varied to -any point between these limits
according to speed, water depth, and wave conditions en
countered. The deeper of the two drafts is used at high
speeds in smooth or rough seas in deep water.
Underwater hull d6 is elliptical in cross-section but,
cient distance to provide a nearly circumferentially uni
55 form flow of water into the propeller, a condition favor
able for maximum propulsive eiiîciency.
Thus it is seen that the shapes described in this inven
tion diñîer from those in a conventional surface ship in
as can be seen in FIG. 25, has a slightly constricted longi
tudinal cross~section, a shape which hydrodynamics re
search indicates to have a minimum wave resistance at
shallow submergences of the body.
that the buoyancy is placed at the greatest practicable
depth below the water surface compatible with operation
as a surface ship.
The various embodiments have in common certain
A propeller 4Z is located on the stern and a rudder 43
other features of form. Each has a streamline elongated
is formed by an extension of the island 67.
form located at the lowest point of the hull, the vertical
Waterline at the shallow submergency WLB. is as 65 center of which is located at from one-half to two and
wide as the waterline of a `conventional ship, and its
one-half body diameters below the water surface. A
initial metacentric stability is also comparable. The ver
tower or towers connect the body with the surface and
tical positions of the center of gravity of the machinery,
the above water portions of the towers form the reserve
fuel oil and cargo, however, are low, all being located
buoyancy. Although embodiments having one, two or
in the underwater `body de of the vessel as near to the 70 three islands have been shown, the number may vary from
inner bottom as possible. A low resultant center of
l to 5 or more without departing from the spirit of this
gravity of the ship is also facilitated by filling all empty
invention. Each embodiment has a rudder and a propel
innerbottom tanks '7l with sea water as the oil is depleted.
ler or propellers mounted on the stern of the craft.
A low resultant center of gravity is necessary to insure
All embodiments also have a center of volume 45 of
the positive -stability at all immersions.
75 the reserve buoyancy and a center of volume 46 of the
underwater portion of the island or islands both for
ward of the center of volume 47 of the body. This im
portant feature is new and useful in this invention and
inherent pitching control. It has been relied upon to
provide all of »the pitching control in all of the embodi
ments of this invention except in the configurations shown
is mainly relied upon to insure effective hydrodynamic
in FIGS. 6 through 20 and 26 thru 30, wherein auxiliary
control of the pitching motion.
Ct stern planes 54 and »bow planes S6 give an additional
Removing most of the immersed volume of a surface
amount of pitching control.
ship to the greatest practicable depth as accomplished
The statical stability of subsurface craft is a consider
by this invention allows the resistance and the speed char
ation which greatly influences the choice of form. The
acteristics approach those of a high speed submarine.
two main types of stability are defined as follows:
This is done by making the portions of the hull in the
Metacentric or surface ship stability is created by im
immediate vicinity of the water surface, that is the wave
mersion and emersion of wedges of volume at the water
making portions, as small as possible consistent with re
plane of a floating body as it is being heeled. Metacentric
taining the simplicity of surface ship control and provid
stability is maximized for a given volume by the largest
ing sufficient internal volume.
and broadest water-plane in the direction of heeling.
Removing most of the volume of the surface ship to
Pendulum stability, on the other hand, is created ‘by the
the greatest practicable depth as in the present invention
ship’s weight acting through its center of gravity, which
causes a reduction in heaving and pitching motion to a
is below -the center of buoyancy. Pendulum stability is
small percentage of that of a conventional surface ship.
maximized for a given volume by the greatest possible
Rolling amplitudes are of the same order of magnitude
distance between the center of gravity and the center of
as that of a conventional ship but are subject to being
buoyancy (analogous to the length of a pendulum). As
drastically reduced by means of mechanical devices such
can be seen the metacentric .type of statical buoyancy is
as anti-rolling fins. Thus, a hull form all of whose major
possessed by surface vessels and the pendulum type of
motions are either inherently small or subject to being
submarines. Because the sub-surface craft of this inven
greatly minimized, can now approach for the first time
tion processes some of the characteristics of both types
the goal of the surface ship having zero motion in a sea
25 its statical stability also takes on some of the character
Way. This has obvious operational advantages.
istics of both types. The transverse statical stability of
The propulsive efficiency of the ship depends upon the
certain types of sub-surface craft whose islands are
propeller efliciency, and also upon the hull-controlled and
located on the center line of the underwater hull is almost
sea-controlled flow conditions under which the propel
entirely of the pendulum type. In each case the water
ler operates. Significant improvements to the ilow en
plane is very narrow transversely. The immersed and
vironment of the propeller are made by this invention. 30 emersed wedges of buoyancy as the vessel heels about the
These improvements relate to nearer approaches to steady
longitudinal axis, are so small in relation to the immersed
state ñow conditions in both smooth water and rough
volume, that these craft have a negligible transverse meta
seas. By placing the propeller 42 low at the same volume
centric stability. Thus, the center of gravity of such
of the bulk of the immersed volume, the effects of a rough
vessels must be so low as to be below the center of buoy
sea varying both velocity and direction. of the water flow
ancy thus forming a pendulum stability.
into the propellers is greatly minimized over that of the
The embodiment of FIGS. 16-20 however, has a con
conventional surface ship. Thus the propulsive efficiency
siderable metacentric component because the forward two
in rough water is maximized.
islands are spaced widely apart in a transverse direction.
In addition, the circular or near-circular hull shape in , As a result, the wedges of change in buoyancy while
a region forward of the propellers in this invention gives
heeling have a larger transverse moment arm, giving
a nearly circumferentially uniform flow distribution into
an appreciable metacentric stability. Because of this
the propellers. Thus, if each propeller blade element is
feature, the center of gravity does not need .to be as low
adapted to the velocity and direction of flow it exper
as for craft of the preceding type in order to provide
iences at its particular radius, the fíow condition will
for an adequate transverse stability. Pendulum stability
remain nearly constant as the blade element sweeps
around its circumference. This flow condition contrasted
with the actual unsymmetrical flow condition of a con
ventional surface ship, produces increased propulsive ef
Pitching angles are limited and the draft of the forms
of this invention is so deep that slamming is eliminated.
Also the position of the centers of buoyancies of the re
serve buoyancy 45 and the immersed portion of the island
46 are placed forward of the center of buoyancy of the
body 47 for reasons of seaworthiness and pitching con
trol. A consequence of this relation of ehapes is dry
decks in a head sea.
Another more important result is
a positive type of pitching response to waves, that is,
when a wave crest is encountered, the bow goes up; if a
is Still present but is proportionately not as large as in
previous craft in making up the total transverse stability,
which is always the algebraic sum of the metacentric and
pendulum stability.
The longitudinal static stability of subsurface craft is
mostly of the metacentric type. The long slim shape of
waterplane whether it be of the single island or twin island
configuration, makes for a considerable wedge volume in
the act of pitching; that is, when the hull is rotated about
a transverse axis. For this reason metacentric stability is
predominant. A small amount of pendulum stability is
still present, however, because the center of gravity must
be low enough to satisfy the requirements for transverse
The embodiments showing variable draft ships vary
wave trough is encountered the bow goes down. This 60 their immersion to suit the speed, water depth, and wave
response prevents uncontrollable diving or leaping in a
conditions encountered. The shallower of the two drafts
sea-way. An uncontrollable diving condition has proven
is used when at low speeds, while entering harbor, and
to be an insuperable disadvantage in previous craft of
whenever accurate maneuvering needs to be done next
this type.
to a dock or pier. The deeper of the two drafts is used
ln the condition of slower speeds and following seas,
at high lspeeds on rough seas wherever a large depth of
which has proven to be the most uncontrollable in pre
water is available. Displacement changes from one depth
vious craft, the water particles in the wave crest travel
to another are accomplished vby the variable water ballast
in the same direction as the ship. For this reason, dy
tanks 68 and 69 shown in FIG. 2l. When these tanks are
namic forces for pitch and depth control such as stern
empty, the ship floats high in the water; when water is
planes or bow planes, are relatively ineffective. Reserve 70 pumped into the tanks the ship sinks to the new deeper
buoyancy has to be mostly relied upon to insure a level
water line.
pitching attitude.
This buoyancy must be forward to
provide the necessary forward moment arm for vertical
buoyancy restoring forces, and to Isense changes in the
height of waves. Buoyancy arranged in this way gives
Operation at high speeds in rough water is optimized
by two criteria: (l) A large displacement-length ratio
(short heavy ships), and (2) A long pitching period.
The addition of water into the tanks of the ship increases
the former criteria by increasing the displacement, and
lengthens the natural pitching period of the hull by in
creasing the longitudinal radius of »gyration, and thus the
longitudinal mass moment of inertia, by reducing the
water plane size, and also by increasing the displacement
substantially circular in vertical cross-section with a pro
peller rotatably mounted at the tip thereof, and the verti
cal cross-section of the remaining portion of said under
water hull is substantially elliptical with a horizontal major
3. A ship comprising a spindle shaped underwater hull
having a mid section which is constricted transversely,
said underwater hull having at least one island attached
ship experiences from a head sea condition by avoiding
thereto at the constricted portion thereof, a portion of
To increase the transverse stability of the ship while 10 said inland being submerged `and having a small cross
sectional area at the plane of the water line as compared
it is changing from one waterline to another, any empty
of the vessel.
The longer pitching period decreases the response the
intenbottom tanks 71 are filled with seawater vthus. main
to the longitudinal cross-sectional area of said underwater
taining a low center of gravity. Normally these tanks,
bounded by the outer bottom and the interbottom of the
hull; and means including the physical dimensions of said
hull and said island whereby the vertical center of said
ship are filled with :fuel oil, except when some of the oil 15 underwater hull lies between `one-half and two and one
has been consumed by the engines.
half hull diameters below the water line surface.
Thus there have been described several embodiments
4. The invention as defined in claim 3, wherein the
of a sub-surface craft combining the advantages of a sur
stern portion of said spindle shaped underwater hull is
face vessel and a submarine without the inherent dis
substantially circular in vertical cross-section with a pro
advantages of each. The vessel of this invention inher 20 peller rotatably mounted at the tip thereof, and the verti
ently combines controlled pitching motion in rough seas,
cal cross-section of the remaining portion of said under
deck dryness, high top speeds, and a maximum propulsive
water hull is substantially elliptical with a horizontal
eñìciency from the propeller~hu1l combination.
major axis.
=It should be understood of course, that the foregoing
5. The invention as defined in claim 4, wherein the
disclosure relates to only preferred embodiments of the 25 center of buoyancy of the portion of the ship above water
invention and that it is intended to cover all changes and
andthe center of Ibuoyancy of said submerged portion of
modifications of the examples of the invention disclosed
said island are both forward of the center of buoyancy
herein which do not constitute departures from the spirit
of the body of the ship.
and scope of the invention.
What is claimed is:
References Cited in the tile of this patent
1. A ship comprising a spindle shaped underwater hull
to which are attached a plurality of islands, a portion of
said islands being submerged, the total cross-sectional
area of said islands in the plane of the water line being
small as compared with the longitudinal cross-sectional 35
Lundborg ___________ .__
Baker ______________ _..
Hoar _______________ __
Perley _____________ __
physical dimensions of said hull and said islands whereby
Blair ____________ __`____ Apr. 8, 1930
the elliptical center of said underwater hull lies between
one-half and two and one-half hull diameters below the
waterline surface; two of said plurality of islands being 40
Engelman ___________ __ Dec. 7, 1937
Piry ________________ __ May 26, 1959
France _____________ .__ Jan. 30, 1925
Germany ___________ __ Nov. 18, 1932
Germany ____________ __ Jan. 4, 1934
Italy ________________ __ Mar. 9, 1943
area of said underwater hull; yand means including the
attached in >side-by-side relationship perpendicularly to
the surface of the forward portion of said underwater hull
and :a platform connecting at least two of said plurality
of islands above the waterline.
2. The invention as deñned in claim 1, |wherein the
stern portion of said spindle-shaped underwater hull iS
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