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US 7,407,366 B2Granted
Propeller combination for a boat propeller drive having double propellers
AssigneeAB Volvo Penta
InventorsBenny Hedlund, Kare Jonsson
Life of this patent
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Abstract
Propeller combination for an aft-mounted boat propeller drive unit with counter-rotating pushing propellers (8,9). The forward propeller (9) is made with blades (12) which have blade tips with an outer edge (b) which approaches a straight line. The width of the blade tip is between 40% and 45% of the maximum width of the blade.
Claims8
A propeller combination for an aft-mounted boat propeller drive unit with pushing propellers, said propeller combination comprising:
- a multi-blade forward boat propeller (9) and a multi-blade after boat propeller (8), said boat propellers rotating in opposite directions about a common rotational axis during operation;
- and
- at least one blade (12) of the forward boat propeller (9) has a curved front edge (c) and a curved rear edge (d), which join, via distinct transitions (f, g), a blade tip with an outer edge (b) which in flattened projection has a greater radius of curvature than the radii of curvature of the front edge and the rear edge in the blade portion radially outside the blade profile section (e) of maximum blade width.
Dependencies are inferred from the claim text.