Ships – Displacement-type hull
Patent
1996-03-29
1998-11-10
Basinger, Sherman
Ships
Displacement-type hull
114140, B63B 104
Patent
active
058328556
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ship'hull comprising a first hull part and, disposed under the first hull part, a second hull part which extends over at least substantially the full length of the first hull part and which is designed as an extremely slender float.
2. Discussion of the Background
A ship'hull of this type is known from DE-41 25 187 A1. The ship'hull described therein has many curved surfaces and is necessarily built in epoxy or the like with the aid of an expensive molds.
SUMMARY OF THE INVENTION
The ship'hull according to the invention on the contrary is easy to produce at substantially every shipbuilding yard and an expensive molds is not required. It is characterized in that both the first hull part and the second hull part are designed as at least substantially hard chine hulls having joint chine frame components.
A preferred embodiment of the invention is characterized in that the first hull part is disposed on the second hull part in such a way that in service conditions the fore half of the first hull part is above water level and the aft half of the first hull part is at least partly below the water level. The advantage is that a bow wave inevitably produced by the first hull part arises under the ship's hull and brings about an upward pressure near the center of the ship's hull.
A further preferred embodiment of the invention is characterized in that the second hull part provides from 70% to 90% of the buoyancy in service conditions. For these values the hull does not give rise to resonance phenomena, keeping the wave-induced drag low, while the second hull part still gives the hull a sufficient transverse stability.
From tests with a model on a scale of 1 to 10 it follows that resonance phenomena giving rise to the wave-induced drag do not occur, even at speeds higher, and even significantly higher, than the ship-bound critical hull speed. It is true that in a measuring range from zero to four times the ship-bound critical hull speed, the wave-induced drag increases, but the slope discontinuity in the graph of the wave-induced drag as a function of speed is absent. Therefore, sailing at speeds far beyond the ship-bound critical hull speed is practicable without an excessive increase in fuel consumption.
To be able to achieve that at a different load, too, the first bow wave from the first hull part and the second bow wave from the second hull part neutralize each other at least substantially, the second hull part can be provided with at least one ballast tank.
As to the ship's hull according to the invention it can be stated that it is a synthesis of the so-called super-slender water displacer having a width-to-length ratio of e.g. 6.5% and the classic ship's hull, for instance, the hard-chine hull having a width-to-length ratio of e.g. 30%.
A further favorable embodiment of the ship's hull according to the invention is characterized in that the width-to-length ratio of the first hull part amounts to 27%-38% and that of the second hull part amounts to 6%-9%.
In another preferred embodiment of the invention, the second hull part is designed so as to widen in the downward direction. This makes it easier to arrange the engine, fuel tank, fresh-water tank and ballast tanks and enables the hull to be put aground in a stable condition on a shoal, while the wave-induced drag is not significantly increased.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be further explained with reference to the accompanying drawings, in which:
FIG. 1 is a side view of the ship's hull in service condition;
FIG. 2 is a plan view of the ship's hull in service condition;
FIG. 3 is a graph of the engine power required for a 10 m long ship's hull according to the invention;
FIG. 4 is a simplified body plan of the ship's hull;
FIG. 5 is a graph of the self-righting moment of the ship's hull according to the invention;
FIG. 6 is a graph of the step response for rotation about the longitudinal axis of the ship's hull according to the inventi
REFERENCES:
patent: 2167689 (1939-08-01), Scowley
patent: 2361409 (1944-10-01), Munro
patent: 3138130 (1964-06-01), Morgan
patent: 4089286 (1978-05-01), Scheel
patent: 4843989 (1989-07-01), Langenberg
Basinger Sherman
Hollandse Signaalapparaten B.V.
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