Forestay-Mounted Sail Furling Device with Tensioning Cable
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Solution Overview
Problem
Existing sailboat head-sail furling and tensioning systems require manual adjustment and can cause deformation of the forestay, are not well-suited for changing sail sizes, and require significant effort and risk of entanglement.
Innovation Solution
A device with a winding head and tensioning system that allows remote operation from the cockpit, featuring a static and movable part for hooking/unhooking the sail, and a tensioning cable that winds/unwinds the sail around the forestay, reducing sail surface area without deforming the mast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional furler with a large drum and sleeve is used, then the headsail can be furled around the forestay, but the weight of the sleeve causes deformation of the forestay curvature and amplifies the stay's cant downwind
Solution Approach 1:
The furling system is divided into separate components: a small drum (16) mounted on the forestay, a furling line (30) that runs through a guide pulley (28), and a separate tensioning system. This segmentation eliminates the need for a large heavy sleeve while maintaining furling functionality, thus preserving the forestay's natural curvature.
Solution Approach 2:
The heavy sleeve component is completely removed from the system. Instead, a lightweight drum (16) is mounted directly on the forestay, and the furling action is achieved through the furling line (30) and guide pulley (28) mechanism, extracting the problematic weight element while keeping the essential furling function.
2Adaptability or versatility
If a single large headsail is used with a furler, then the surface area can be adjusted by furling, but the cut and depth are a compromise and far from being as well cut as each of the sails in a set
Solution Approach 1:
The furling system is designed to be universal and compatible with multiple different headsail configurations. The small drum (16), guide pulley (28), and furling line (30) mechanism can work with various sail types including genoa, jib, and asymmetrical spinnaker, allowing sailors to use optimized sails for different conditions rather than compromising on a single universal sail cut.
Solution Approach 2:
The system allows dynamic adjustment of sail surface area through partial furling using the furling line (30), enabling sailors to optimize sail area for different wind conditions while maintaining the ability to use multiple specialized sail cuts for different sailing scenarios.
3Ease of operation
If the headsail is tensioned using a halyard taken up at the top of the mast, then the sail can be tightened, but the significant tensile forces are taken up by the mast and a crew member must go to the foot of the mast to operate the halyard
Solution Approach 1:
A guide pulley (28) is introduced as an intermediary element that redirects the furling line (30) from the drum (16) on the forestay to an accessible location on the deck. This allows crew members to tension and furl the sail from the cockpit without needing to access the foot of the mast, reducing both operational complexity and mast load requirements.
Solution Approach 2:
The traditional halyard system that requires mast-top tensioning is replaced with a forestay-mounted drum (16) and furling line (30) system operated through a guide pulley (28). This substitution moves the tensioning mechanism from the mast to the forestay area, allowing deck-level operation and reducing mast load.
4Adaptability or versatility
If manual sail changing is performed by going to the front of the boat, then sails can be lowered and replaced, but this requires significant manual effort and time
Solution Approach 1:
The furling system enables sails to be furled and unfurled automatically through the drum (16) and furling line (30) mechanism operated from the cockpit. This self-service capability allows rapid sail changes without crew members needing to physically go to the front of the boat to manually handle the sails, significantly reducing the time and effort required for sail changes.
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
Enables efficient and safe remote furling and tensioning of sails, reducing sail surface area without deforming the forestay, and allowing for quick sail changes without manual effort or risk of entanglement.
Implementation Method 1
a friction bearing (7) secured to the rotating part (61)
Implementation Method 2
a threaded rotating part (62) extending along an axis coaxial with the longitudinal axis X-X' of the stay (5)
Implementation Method 3
an axis (41) for locking the rotation, capable of sliding along an axis coaxial with the longitudinal axis X-X' of the stay (5), inside the groove (45) compressed by a spring R
Data Source
Figure 1
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AI summary
The device has a stretching unit including a stretching cable (8) whose end (81) is integrated to an anchoring point (12) distributed along a luff (11) of a front sail (2). The point and a lower end (9) of the luff are confounded such that traction exerted on another end (82) of the cable actuates a rotatable driving foot to rotatably drive a stay (5) around its longitudinal axis (X-X') by winding the sail around the stay, and traction exerted on the cable actuates the foot in reverse direction by unwinding the sail. The cable is wound around a tube (3) integrated to the foot.