Ship hull

A ship hull comprises at least one longitudinally directed displacement body which is symmetric to the longitudinal axis of the ship and which is adjoined by gliding surfaces at least at both longitudinal sides or, as the case may be, on all sides, being provided at the underside of the hull. The quantity of water displaced by the displacement body substantially corresponds, with respect to weight, to the total weight of the ship, so that the gliding surface lies substantially horizontally and on or in the vicinity of the surface of the water. The gliding surfaces are constructed in a wave-shaped manner in the longitudinal direction and, as the case may be, also in the transverse direction of the ship hull, wherein the wave shape of the gliding surfaces is displaced by approximately 180.degree. relative to the natural waves generated by the displacement body, so that the natural waves are virtually canceled during travel through the water.

BACKGROUND OF THE INVENTION 
a) Field of the Invention 
The invention relates to a ship hull, at least one longitudinally directed 
displacement body which is symmetric to the longitudinal axis of the ship 
and which is adjoined by gliding surfaces at least at both longitudinal 
sides or, as the case may be, on all sides, being provided at the 
underside of the hull, wherein the quantity of water displaced by the 
displacement body substantially corresponds, with respect to weight, to 
the total weight of the ship, so that the gliding surfaces lie 
substantially horizontally and on or in the vicinity of the surface of the 
water. 
b) Description of the Related Art 
In a hull of the type mentioned above, it was known (U.S. Pat. No. 
3,698,342 A) to construct the gliding surfaces as flat surfaces. However, 
essentially the usual development of waves takes place when the ship 
travels through the water, without any special effect being achieved. 
Not only does the wave formation consume driving energy, but damage to 
embankments or shoreline structures results especially when the ship 
travels in built up areas. Where buildings are concerned, well-known 
damages result (Venice). 
OBJECT AND SUMMARY OF THE INVENTION 
It is one of the objects of the invention to overcome the problems 
described above. According to the invention, this object is met in a ship 
hull of the type mentioned above when the gliding surfaces are constructed 
in a wave-shaped manner in the longitudinal direction and, as the case may 
be, also in the transverse direction of the ship hull, wherein the wave 
shape of the gliding surfaces is displaced by approximately 180.degree. 
relative to the natural waves generated by the displacement body, so that 
the natural waves of the displacement body are virtually canceled during 
travel through the water. 
Due to the construction of the gliding surfaces of the ship hull according 
to the invention, the wave formation and therefore the drawbacks resulting 
therefrom can be prevented or eliminated. In particular, there is a 
considerable savings in driving energy for the entire ship. 
In this connection, it must be taken into account that when the ship is 
traveling through calm water it must overcome essentially three 
counterforces. The least of these counterforces is wind resistance, the 
next strongest is the frictional resistance of the submerged or underwater 
surface, and the most important is the form resistance given by the 
respective construction of the underwater hull. This form resistance or 
residuary resistance is composed of the wave resistance, the pressure 
resistance and the inductive resistance, wherein the latter is caused by 
leeway and is small. 
As is well known, a displacing, non-gliding hull forms waves when traveling 
through the water, which uses up energy. At low speed, the length of the 
wave is initially small (which can usually be seen quite clearly at the 
ship's side) and increases as the speed increases until it is finally 
equal to the waterline length of the ship. From that point, the resistance 
of a displacing body increases enormously. 
The invention is based on the following idea: initially without 
consideration to the desired width of the ship, the ship hull should 
comprise a longitudinally directed part which is as streamline-shaped as 
possible, which has low resistance in itself and whose volume corresponds 
to the total displacement of the ship. In or in the vicinity of the 
waterline of the ship, essentially horizontal gliding surfaces adjoin this 
displacement body on the left and right sides as well as somewhat toward 
the front and the rear. 
Parallel shoulders which extend vertically downward and which are narrow in 
comparison to the depth of the displacement body can be located at the 
outer edges. 
Naturally, the underwater hull can also be formed of a plurality of 
displacement bodies of this kind, wherein the gliding surfaces are located 
between these displacement bodies and at the outer edges thereof. 
Considered by itself, that is, without the gliding surfaces, the 
displacement body forms waves of determined length, depending on speed, 
when traveling through the water. The adjoining gliding surfaces are 
shaped in a wave-shaped manner in the longitudinal direction and, as the 
case may be, in the transverse direction according to the invention in 
such a way that the waves of the displacement body are canceled by their 
influence and, also, no further waves occur. 
Drag tests with ship models constructed in accordance with the invention 
showed, for example, that a wave of the gliding surfaces which has only a 
small depth relative to the depth of the displacement body and which is 
displaced by about 180.degree. relative to the natural waves of the 
displacement body in the longitudinal direction has favorable results as 
regards the object of the invention. Subsequent extrapolations of the drag 
test with three different models on ships of corresponding size, all of 
which have a length of 14 m, a width of 4.5 m and a displacement of 21 
tons, gave the following necessary drag power at a traveling speed of 25 
km per hour: 
______________________________________ 
boat (DG boat) constructed according to the invention 
11 kW 
conventional gliding boat or hydroplane 
197 kW 
conventional displacement boat 
245 kW 
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Many utility or commercial craft (fishing boats, etc) normally move in 
these speed ranges. 
Naturally, the construction of the hull in accordance with the invention 
has a greater surface and consequently a higher frictional resistance 
compared with almost any other conventional ship shape. Nevertheless, the 
total resistance is much lower, so that driving energy can be saved. 
In order to reduce the frictional resistance, the following measures may be 
taken in addition: 
As was stated above, narrow, vertically extending longitudinal shoulders 
are mounted at the parallel side edges of the underwater hull, wherein 
these longitudinal shoulders are submerged in the water only slightly and 
thus prevent lateral spray or splash water and increase the directional 
stability of the ship. This also enables a purposeful injection of 
compressed air by means of nozzles which are located in the front part of 
the gliding surfaces in order to prevent the frictional resistance of the 
gliding surfaces by breaking up the interface between the water and 
gliding surfaces. 
To summarize, the invention has the following advantages over all previous 
underwater shapes of ships: 
1. Substantially smaller total resistance when traveling through water at 
all speeds compared with conventional displacement boats. 
2. Substantially lower total resistance when traveling through water 
compared with conventional gliding boats or hydroplanes in the speed range 
before hydroplaning. 
3. Virtually no wave formation when traveling through the water, protection 
of bank and buildings on water as, e.g., in Venice. 
In a special construction of the hull according to the invention, this hull 
can be provided with compensation tanks to compensate for weight 
variations of the ship. 
The invention will be explained more fully hereinafter with reference to 
the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The displacement body is designated by 1 in the drawing. Gliding surfaces 2 
with waves in the longitudinal direction and/or transverse direction 
adjoin the displacement body 1 laterally, wherein the wave-shaped 
construction in the longitudinal direction is shown most clearly by the 
dashed lines in FIGS. 4 and 8. In some cases, every gliding surface 2 can 
pass externally into gliding strips 3 which are shaped so as to be flat. 
If required, shoulders 4 whose height h1 is approximately equal to the 
wave amplitude h2 of the lateral gliding surfaces 2 can also project 
downward from the outer edge of the gliding strips 3. In the drawing, the 
waterline is designated by 5 and the arrow P designates the traveling 
direction. Longitudinal chambers which are closed laterally and on top are 
formed underwater between the shoulders 4 and the displacement body 1, 
wherein air can be injected into these longitudinal chambers in the front 
through nozzles and is then retained along the entire length of the ship 
while traveling through the water so as to prevent friction through the 
breaking up of the interface or boundary layer. The gliding surfaces 2 and 
3 should lie on the surface of the water as far as possible which, if 
necessary, can be ensured by means of compensation tanks. 
FIGS. 6 and 7 only show the displacement body 1 of the underwater hull with 
the wave pattern generated by the displacement body 1 while traveling 
(traveling direction P) through the water, wherein the generated natural 
wave 6 is shown in FIG. 6 in longitudinal section. A first wave crest 7 
extends diagonally outward and to the rear at an angle .alpha. (FIG. 7) 
relative to the longitudinal axis of the underwater hull. After a wave 
trough 8, a subsequent second wave crest 9 is shown by way of example. 
FIGS. 8 and 9 show the underwater hull with the displacement body 1 and the 
gliding surfaces 2. The two gliding surfaces 2 on either side of the 
displacement body 1 have bulging waves 10 and 11 at those locations where 
the wave crests 7' and 9' are generated by the displacement body 1 by 
itself and are accordingly constructed in opposite direction thereto or so 
as to be displaced by 180.degree. in the longitudinal direction. The wave 
of the gliding surfaces 2 follows the angle .alpha. in the transverse 
direction. A wave formation is extensively prevented by means of this 
arrangement of the gliding surfaces 2. 
While the foregoing description and drawings represent the preferred 
embodiments of the present invention, it will be obvious to those skilled 
in the art that various changes and modifications may be made therein 
without departing from the true spirit and scope of the present invention.