Patent ID: 9745948
Date: 2017-08-29
CPC Classifications: B63H,F03B

Claim:
1. A marine propeller comprising: an outer hub having a central axis; and a blade having a blade root attached to the outer hub and extending radially outward from the outer hub toward a blade tip, the blade having a leading edge and a trailing edge; wherein the propeller has a diameter between 15.5 inches and 16.5 inches; wherein the propeller has a pitch between about 17 inches and about 23 inches; wherein the blade has a progressive rake angle such that a first local rake angle at the blade root is less than a second local rake angle at the blade tip; wherein the propeller has an expanded blade area ratio between about 0.52 and about 0.61; wherein the expanded blade area ratio is related to the pitch such that an upper limit of the expanded blade area ratio is defined by the relationship EBAR=−0.005*P+0.685 and a lower limit of the expanded blade area ratio is defined by the relationship EBAR=−0.005*P+0.635, where EBAR is the expanded blade area ratio and P is the pitch; wherein the blade has an average rake angle from the root to the tip, and the average rake angle is related to the pitch such that an upper limit of the average rake angle is defined by the relationship R=0.02083*P^3−1.4643*P^2+34.372*P−238.44 and a lower limit of the average rake angle is defined by the relationship R=0.02083*P^3−1.42*P^2+32.5506*P−226.209, where R is the average rake angle; wherein the blade has a maximum cross-sectional thickness at a location between about 25% and about 40% of a length of a chord extending from the leading edge to the trailing edge, as measured from the leading edge; and wherein a combination of the diameter, pitch, progressive rake angle, expanded blade area ratio, average rake angle, and location of the maximum cross-sectional thickness minimizes a drag on a marine vessel to which the marine propeller is coupled while the marine vessel is operating at less than a maximum vessel speed.