(57) Planing vessels of improved performance capability and methods for improving such
performance and foils which may be associated with a planing vessels for providing
improved performance capability. A dynamic downward force generated as the vessel
(1) moves through water, preferably by a foil (3), is imposed on the vessel, with
the locus of the force positioned, in the transverse direction, at the longitudinal
vertical centerline plane of the vessel. In the longitudinal direction the locus of
the dynamic force is positioned, relative to the other forces acting fore-to-aft on
the vessel, to decrease the trim angle of the vessel, desirably to less than two degrees.
Vessel wetted surface configurations are provided for stable and efficient operation
at low trim angles, including the following. A deep draft, fine entrance (32) which
minimizes rise at the bow experienced with conventional planing vessels and assists
in maintaining laminarity of flow at the planing surfaces. A foil (31) extending along
the bowpeak below the waterline and spaced forwardly thereof streamline the flow passing
the bow to thereby decrease spray and turbulence. A skeg (32) extending downward at
the bottom of the hull at the entrance along the longitudinal centerline plane which
improves directional stability and also assists in maintaining flow laminarity. A
sweptback wing located at the entrance, preferably mounted at the lower margin of
the skeg positioned with an angle of attack which generates an upward force to improve
the vessel stability against pitch and yaw in disturbed water. An aftmidships planing
floor (11) having a rise from midships to the stern trailing edge desirably from 50%
to 100% of the midships draft improves the stability of the vessel when operated at
trim. A release floor (21) extending aftward 5 to 25% of the waterline length of the
vessel, preferably from a transverse step (4), and rising over this length 10 to 50%
of the midships draft to a transverse trailing edge (22). The trailing edge and the
release floor, in the transverse direction, are parallel with base plane of the vessel.
The pressure release floor reduces the pressure on the aftward flow to separation
at the trailing edge in a gradual and uniform manner which reduces drag. Chine lines
(12) at the margins of the aft planing floor are provided with fins which extend aftwardly
and upwardly of the stern trailing edge to effect a smooth flow separation. The foil
to generate a downward force in the flow desirably is positioned below the stern trailing
edge and contoured to produce minimum induced drag and to divert the flow at its trailing
edge downwardly so as to reduce turbulence and drag at the stern.
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