Reverse Gate Deflectors for Jet Watercraft Stability
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Solution Overview
Problem
Jet propelled watercraft with reverse gates experience pitching and rolling when reversing, and there is a loss of thrust due to apertures in the sides of the reverse gate when the steering nozzle is not turned, which complicates deceleration and maneuverability.
Innovation Solution
A reverse gate design with deflectors and water deflecting surfaces that redirect water upwardly and laterally, reducing pitching and rolling, and incorporating turning deflectors to minimize water flow through apertures when the steering nozzle is not turned, enhancing thrust and deceleration capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the reverse gate is lowered while moving in the forward direction and steering the watercraft, then the watercraft can reverse direction, but the thrust created by the redirected water jet causes the watercraft to pitch and slightly roll
Solution Approach 1:
The reverse gate is divided into multiple segments: a main reverse gate body and separate deflectors (upward deflector and lateral deflector). Each segment performs a specific function - the main body redirects water rearwardly for reverse thrust, while the deflectors separately manage water flow to prevent pitching and rolling. This segmentation allows independent optimization of each function without compromising the others.
Solution Approach 2:
The deflectors act as intermediary elements between the main reverse gate and the water jet. The upward deflector intercepts water that would cause pitching, redirecting it upward. The lateral deflector intercepts water that would cause rolling, redirecting it laterally. These intermediaries modify the water flow before it reaches the watercraft, eliminating the harmful effects while preserving the reverse thrust function.
2Ease of operation
If apertures are provided in the sides of the reverse gate to assist in steering when moving in reverse, then lateral thrust is created for steering, but water exits through the apertures even when the steering nozzle is not turned, reducing the amount of thrust generated to cause the watercraft to move in the reverse direction
Solution Approach 1:
The lateral deflector is positioned to preliminarily intercept and redirect water flow before it can reach the apertures in the reverse gate. When the steering nozzle is not turned, the lateral deflector prevents water from entering the apertures, ensuring all water contributes to reverse thrust. When steering is required, the lateral deflector redirects water laterally through the apertures to create steering thrust. This preliminary action by the deflector eliminates unnecessary thrust loss.
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 design reduces pitching and rolling tendencies, maintains thrust when reversing, and improves deceleration efficiency by minimizing water loss through apertures, providing a more stable and effective reverse maneuvering system.
Implementation Method 1
The jet propulsion system typically consists of a jet pump which pressurizes water from the body of water and expels it through a venturi as a jet rearwardly of the watercraft to create thrust
Implementation Method 2
A first water deflecting surface is connected to the first side wall adjacent to the first aperture and extends away from the first side wall. The first water deflecting surface extends at least in part along a lower edge of the first aperture and extends upwardly from the first side wall
Implementation Method 3
A first turning deflector is connected to the inner arcuate surface of the reverse gate body. A second turning deflector is connected to the inner arcuate surface of the reverse gate body
Data Source
AI summary
A watercraft has a hull, a deck, an engine, a steering assembly, a jet pump, a venturi, a steering nozzle, and a reverse gate pivotable between a fully stowed position and a fully lowered position. The reverse gate includes a reverse gate body having inner and outer arcuate surfaces, and reverse gate upper and lower edges. First and second side walls are connected to the sides of the reverse gate body. At least one deflector is connected to at least one of the outer arcuate surface, the first side wall, and the second side wall. The at least one deflector is spaced from the outer arcuate surface. A deflector trailing edge is disposed upwardly and rearwardly from a deflector leading edge at least when the reverse gate is in the fully lowered position. Water deflecting surfaces and turning deflectors connected to a reverse gate are also disclosed.