US 6,475,045 B2 · Thrust enhancing propeller guard assembly

Abstract

A propeller guard assembly for water craft that, in cooperation with a rotating propeller, creates a substantial increase in propulsive thrust and provides improved all around shielding of the latest state of the art propeller configurations. The increase in propulsive thrust of the propeller guard assembly of the invention is created primarily by the angle of the attack and hydrofoil cross section of the four guard rings or cowlings of the device. A secondary reason for the increase in propulsive thrust of the propeller guard assembly of the invention resides in the fact that the thrust realized is equal to the ratio between the effective projected propeller area and the area of trailing edges of the large primary and secondary guard rings which decreases the tendency of the propeller race to spread, particularly at high propeller slip during acceleration and take off.

Claims10

Dependent claims

A thrust enhancing propeller guard assembly for mounting on a housing of a motor for rotating a propeller about a longitudinal axis, the propeller functioning to propel a boat through the water, the thrust enhancing propeller guard assembly comprising:

(a) first generally ring shaped cowling of a first diameter connected to the housing at an axially spaced location from the propeller;
(b) a second generally ring shaped cowling of a second, larger diameter connected to the housing at a spaced location from said first cowling, said second cowling circumscribing the propeller and being a generally airfoil shaped in cross section;
(c) a third generally ring shaped cowling of a second diameter connected to the housing at a spaced location from said second ring shaped cowling, said third cowling being generally airfoil shape in cross-section, circumscribing the propeller and being arranged to create an annular space between said second and third ring shaped cowlings for controlling the flow of water there between to create a venturi effect;
(d) a fourth generally ring shaped cowling of a first diameter connected to said housing at a location axially spaced from the propeller and axially spaced from said third generally ring shaped cowling;
and
(e) a pair of oppositely disposed torque bars connected to said first, second, third and fourth generally ring shaped cowlings.

3 more elements

A thrust enhancing propeller guard assembly for mounting on a housing of a motor for rotating a propeller about a longitudinal axis, the propeller functioning to propel a boat through the water, said housing includes a cavitation plate and a skeg, the thrust enhancing propeller guard assembly comprising:

(a) a first mounting member connected to said cavitation plate;
(b) a second mounting member connected to said skeg;
(c) a first generally ring shaped cowling of a first diameter connected to the housing at an axially spaced location from the propeller, said first cowling comprising first and second semicircular segments each having upper and lower extremities, each said segment being connected at its upper extremity to said first mounting member and each of said segments being connected at its lower extremity to said second mounting member;
(d) a second generally ring shaped cowling of a second, larger diameter connected to the housing at a spaced location from said first cowling, said second cowling circumscribing the propeller and being a generally airfoil shaped in cross section, said second cowling comprising first and second semicircular segments each having upper and lower extremities, each said segment being connected at its upper extremity to said first mounting member and each of said segments being connected at its lower extremity to said second mounting member;
(e) a third generally ring shaped cowling of a second diameter connected to the housing at a spaced location from said second ring shaped cowling, said third cowling being generally airfoil shape in cross-section, circumscribing the propeller and being arranged to create an annular space between said second and third ring shaped cowlings for controlling the flow of water there between to create a venturi effect, said third cowling comprising first and second semicircular segments each having upper and lower extremities, each said segment being connected at its upper extremity to said first mounting member and each of said segments being connected at its lower extremity to said second mounting member;
(f) a fourth generally ring shaped cowling of a first diameter connected to said housing at a location axially spaced from the propeller and axially spaced from said third generally ring shaped cowling, said fourth cowling comprising first and second semicircular segments each having upper and lower extremities, each said segment being connected at its upper extremity to said first mounting member and each of said segments being connected at its lower extremity to said second mounting member;
and
(g) a pair of oppositely disposed torque bars connected to said first, second, third and fourth generally ring shaped cowlings.

5 more elements

Dependencies are inferred from the claim text.

Thrust enhancing propeller guard assembly

Life of this patent

Thrust enhancing propeller guard assembly

Life of this patent

Abstract

Claims10