Saildrive Brake Relocation to Reduce Drag
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Solution Overview
Problem
Traditional saildrive systems experience unwanted drag and inefficiency due to propeller shaft elements protruding from the hull, which increase space requirements and disrupt water flow, leading to reduced performance and increased fuel consumption.
Innovation Solution
A saildrive arrangement with a brake mechanism located in the upper unit inside the hull, locking the propeller shaft to prevent rotation when the engine is not running, minimizing external elements and reducing drag by integrating the brake within the hull, thereby enhancing thrust efficiency and planing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the brake mechanism is located in the lower unit outside the hull, then it is easier to access for maintenance, but it increases drag and space requirements outside the hull
Solution Approach 1:
The brake mechanism is extracted from the lower unit and relocated to the upper unit inside the hull. This separation removes the brake from the external environment where it would create drag, while maintaining its functional connection to the propeller shaft through the hydraulic system that extends into the lower unit.
Solution Approach 2:
The brake is nested within the upper unit housing inside the hull, with the hydraulic pump and fluid reservoir integrated into the same space. This compact nesting arrangement accommodates all brake components within the hull volume, eliminating external protrusions that would increase drag.
2Device complexity
If the propeller shaft elements protrude from the hull, then the lower unit can be simplified in design, but it increases space requirements and disrupts water flow
Solution Approach 1:
The brake mechanism is extracted from the lower unit and relocated to the upper unit inside the hull. This separation removes the brake from the external environment where it would create drag, while maintaining its functional connection to the propeller shaft through the hydraulic system that extends into the lower unit.
3Object-affected harmful factors
If the brake is located inside the hull in the upper unit, then drag is reduced and space outside the hull is minimized, but accessibility for maintenance becomes more difficult
Solution Approach 1:
A service access opening is provided in the hull that allows direct access to the hydraulic pump and fluid reservoir within the upper unit. This intermediary access point enables maintenance personnel to service the brake system components without needing to access them from outside the hull, thus maintaining ease of repair while keeping components inside the hull to minimize drag.
4Object-affected harmful factors
If a locking device is used on the propeller shaft, then the propeller can be locked in position to reduce drag when sailing, but the device adds complexity to the saildrive system
Solution Approach 1:
The brake mechanism serves multiple functions: it locks the propeller shaft to prevent rotation during sailing to reduce drag, and it can also serve as the primary braking system for the engine-driven propeller. This multi-functionality eliminates the need for separate locking devices, reducing overall system complexity while achieving the drag reduction benefit.
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 significantly reduces drag and fuel consumption by keeping the propeller blades folded or locked, allowing higher sailboat speeds and improved propulsion efficiency, applicable to both fixed and folding propellers, while maintaining a compact design.
Implementation Method 1
A brake to lock the rotational movement of the propeller shaft is located in the upper unit
Data Source
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AI summary
The invention relates to a saildrive arrangement (1) comprising an upper unit (13) to be positioned inside a hull (5) of a sailboat (7) and a lower unit (14) which is arranged to protrude from the bottom (6) of the hull (5). The upper unit (13) comprises an input shaft (4) to be connected to an engine (2) and the lower unit (14) comprises a propeller shaft (9). A brake (15) for locking the rotational movement of the propeller shaft (9) is located in the upper unit (13). The invention further relates to a sailboat (7) with a hull (5) and a saildrive with an engine (2) and a saildrive arrangement (1).