Marine propulsion – Screw propeller – Having means to control flow around propeller
Patent
1985-03-12
1987-04-28
Peters, Jr., Joseph F.
Marine propulsion
Screw propeller
Having means to control flow around propeller
114 67A, 114288, B63H 516
Patent
active
046610758
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention relates to a self-propelled water-borne vessel.
Patent Specification GB 1 460 947 discloses a self-propelled waterborne vessel in the form of a displacement ducted craft wherein the undersurface of the hull forms a duct at the bow section and an inverted open parallel channel from the middle of the bow to the stern. The duct is provided with power operated water propellant means for propelling water along it. Waterborne vessels embodying the invention disclosed in Specification GB 1 460 947 show considerable improvements in efficiency as compared with conventional vessels, and the present invention is concerned with a self-propelled waterborne vessel, the efficiency of which is still further increased.
In accordance with the invention there is provided a self-propelled waterborne vessel having a hull undersurface shaped to define at least one longitudinally extending channel and propulsion means for propelling water along the channel, the channel having a portion of substantially constant cross-section upstream of the propulsion means and being of variable cross-section downstream thereof.
Preferably, the variation of the channel cross-section is effected by a vane mounted to span across the channel and to be pivoted on a transverse axis. The vane can be pivoted at its forward edge on a fixed vane spanning the channel beneath the propulsion means. A duct for the water moved by the propulsion means is thus created whereby pressure on the bow region of the vessel is reduced and the channel structure strengthened.
In the duct and channel arrangement of the vessel disclosed in Specification GB 1 460 947, a water propellant means is provided in a portion of the duct of which the cross-sectional area diminishes from the bow to the region at which the duct opens into the channel. It has now been found that a channel configuration in accordance with the present invention, in which the propulsion means operates on a stable flow of water in the channel, due to the provision of the upstream portion thereof of substantially uniform cross-section, together with the downstream portion of variable cross-section, provides improved performance and efficiency.
The hull undersurface can be generally flat, with a bow shape and downwardly projecting side walls and/or keels to define the propulsion channel or channels. The or each channel can be generally rectangular in cross-section and can have a length approximating to one third or one half of the length of the vessel. The bow portion of the hull undersurface can be flared in a generally conventional way but is provided with a groove forming the leading portion of the or each channel. Preferably a vessel embodying the present invention is provided with a plurality of the channels defined by the bow and between such side walls and keels, the channels being spaced apart or located in direct adjacency.
A vessel embodying the invention can be provided with additional propulsion means in the stern region. Such additional propulsion means can be arranged to be retractable into the hull during normal operation of the vessel, use being made of them when exceptional power is required, as when great speed is necessary or when the vessel has to tow a large load. The additional propulsion means can comprise one or more propeller or hydrojet propulsion units which can be accommodated in channels or ducts aligned with the first-mentioned propulsion channels.
A vessel in accordance with the invention can be provided with conventional steering means, or steering can be effected by speed adjustment of the propulsion means in adjacent or laterally spaced channels together with speed adjustment of the additional propulsion means if fitted. The additional propulsion means can however be mounted at the hull underside for movement to constitute propulsive steering means. The propulsive steering means can then comprise a propulsion unit supported for rotation about a generally vertical axis so as to apply to the vessel a propulsive force in a selectively variable directi
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Peters Jr. Joseph F.
Sotelo Jesus D.
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