Conformal Roller Furler Assembly for Sail Shape Maintenance
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Solution Overview
Problem
Prior art roller furler systems fail to maintain the aerodynamic properties of sails during reefing due to distortion caused by rolling a three-dimensional curved sail around a straight stay cable, leading to reduced lift and increased risk in close-hauled navigation, and suffer from issues like halyard wrap and disengagement of the upper swivel device.
Innovation Solution
A conformal roller furler assembly with a hollow drive shaft and a flexible sail edge device that twists to maintain the sail's tautness and aerodynamic shape, featuring a torque input device positioned at the sail's geometric center to distribute winding forces evenly, allowing the sail to wind independently of its head and tack connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rigid hollow sail mounting track is used to wind the sail, then the sail can be easily furled, but the sail's airfoil shape becomes distorted and aerodynamic properties are lost
Solution Approach 1:
The patent applies the dynamics principle by making the sail mounting track flexible rather than rigid, allowing it to dynamically adapt its shape during the furling process. The flexible track can bend and conform to the three-dimensional curvature of the sail, maintaining the airfoil shape while still enabling the winding operation. This resolves the contradiction by making the system adaptable rather than fixed.
Solution Approach 2:
The patent changes the physical parameter of the mounting track from rigid to flexible, altering its mechanical properties. This parameter change allows the track to deform and conform to the sail's three-dimensional shape during furling, preventing distortion of the airfoil while still enabling the winding function.
2Device complexity
If the sail is rolled around a straight stay cable, then the furling mechanism is simple, but severe distortion of the airfoil shape occurs
Solution Approach 1:
The flexible mounting track dynamically conforms to the three-dimensional shape of the sail as it winds around the stay cable. Instead of forcing the sail into a rigid circular pattern, the flexible track adapts to the sail's natural curvature, maintaining aerodynamic efficiency while still enabling simple furling operation.
Solution Approach 2:
The patent uses a flexible mounting track that can bend and deform to match the three-dimensional curvature of the sail. This flexible element allows the sail to be wound around the stay cable without distorting the airfoil shape, as the track flexes to accommodate the complex geometry.
3Ease of operation
If the upper swivel device allows free rotation, then the sail can be wound, but torque inputs increase friction and may damage contact points
Solution Approach 1:
The patent changes the rotational characteristics of the upper swivel device by introducing a spring mechanism that provides controlled resistance rather than free rotation. This parameter change in the rotational stiffness allows the sail to be wound while limiting excessive torque inputs, reducing friction and wear on contact points, and improving overall reliability.
4Ease of operation
If the sail mounting track is positioned high on the stay cable, then the sail can be hoisted, but the upper swivel device may become disengaged
Solution Approach 1:
The patent modifies the vertical position parameter of the sail mounting track relative to the stay cable. By positioning the track at an optimized height, the system ensures that the upper swivel device remains engaged during the hoisting operation, preventing disengagement while still allowing proper sail hoisting function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution maintains the sail's aerodynamic properties during furling and reefing, reducing distortion and the risk of halyard wrap, while ensuring the sail remains taut and operational, enhancing safety and performance in various wind conditions.
Implementation Method 1
The flexible sail edge device is made of flexible, medium stiffness, high impact resistance plastic alloy of material such as PVC, polyester, nylon, polycarbonate with a modulus of elasticity in the range of 275,000 psi so that when the drive shaft is rotated, torque or rotational force is directly transferred to the section of luff located adjacent to the torque input device
Implementation Method 2
when the drive shaft is rotated, torque or rotational force is directly transferred to the section of luff located adjacent to the torque input device and perpendicular to the sail's geometric center
Data Source
AI summary
A roller furler assembly for furling a sail where the luff is vertically or diagonally supported by a stay cable. The assembly includes a hollow drive shaft longitudinally aligned around the stay cable adjacent to the luff. A drive mechanism is coupled to the lower end of the drive shaft. Integrally formed or connected to the drive shaft is a torque input device that connects to a portion of a hollow, flexible sail edge device fitted over the middle and upper sections of the drive shaft. The sail edge device includes a longitudinally aligned slot or track that directly connects to a beaded edge attached to the luff. The torque input device is approximately 5%-25% of the stay cable so when the drive shaft is rotated, torque or rotational force is applied directly to the section of the luff located perpendicular to the longitudinal axis of the torque input device.