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3D FRP Hull Surfaces and CNC Machining

Introducing the stories behind Yamaha Motor's technologies.

Yamaha began full-scale mass-production of fiber-reinforced plastic (FRP) boat hulls in 1968 and expanded its range of expertise to include utility boats, fishing boats, pleasure craft and cruisers. In the 1980s when marine leisure began to diversify, calls from the market for faster, higher quality boats spread and expectations grew among enthusiasts for boats that were faster and more comfortable.
To answer these hopes for better FRP boat hulls, in 1989, we introduced Computer Numerical Controlled (CNC) 5-axis machining equipment to our process for creating FRP boat hull molds for the first time in order to achieve higher levels of shaping precision. In creating an FRP hull, the form of the male mold that will eventually determine the hull’s shape must be highly precise, because it directly influences the boat’s performance on the water. We had been previously creating hull molds with 2D maps, but the market needs for higher precision in hull shaping led us to implement this new system.
The “chine” of a boat refers the line running down the side of a hull near the waterline, and the angle in the hull it forms in relation to the boat’s centerline. Its design can improve a boat’s ability to cut through waves and reduce the boat’s hull drag when underway. If the chine is even a few millimeters off, it can greatly affect a boat’s cruising characteristics. With a motorcycle, the shape of the fuel tank doesn’t drastically alter its performance; the fuel tank can be said to be flying through the air, so it isn’t even comparable to the amount of force applied when a boat travels through the water. When you factor in the requirements for a hull to both slice through the waves and have design appeal, the chine area may need a combination of excellent fluid dynamics and smooth, concave surfaces.
When it comes to designing the form of these concave surfaces with 2D mapping, multiple maps of the cross-sectional shape are needed. Veteran engineers would compensate for the technical shortcomings of 2D mapping by deciding on the various points between each cross-sectional blueprint to connect them all to form the overall hull design, but the introduction of CNC machining capability relieved them of this difficult task. It became possible to create a male mold that completely replicated the hull design maps and blueprints.
With CNC machining technology, the hull shape is displayed with three-dimensional data, so (1) large-scale, high-precision machining across five axes and (2) putting together separately molded sections using our multi-piece mold processing technology to make larger hulls become possible. Also, the use of 3D CAD programs and CNC machining technology has made it possible to manufacture FRP boat hulls with ±1 mm levels of accuracy.
After the introduction of our CNC machinery, we had employed it for shaping select hull sections while accumulating know-how for things like data creation and new mold construction. But in 2004, the YF-27 sport fishing boat (#1) became our first product to use a hull fashioned solely from a male mold created by the CNC machine. Its modern styling and excellent performance on the water made it a popular model among consumers. From there, we used the machinery to create a wide range of FRP hulls. Today’s lineup of Yamaha boats, from the F.A.S.T.23 sport fishing boat (#2) to the EXULT 36 Sport Saloon cruiser (#3), all use hulls produced with CNC machinery.
However, simply creating FRP hulls with male molds produced by CNC machinery is not what makes Yamaha Motor different. It is the technical expertise and know-how garnered over many years in the industry, taking advantage of Yamaha’s location near Lake Hamana for testing a boat’s high-speed performance and along the Enshunada Coast for evaluating performance on the waves of the Pacific; both of these testing procedures are also based on valuing human perceptions and feedback (Kanno Hyoka). Another distinctive feature of our FRP boatbuilding process is fine-tuning and confirming the pairing of the hulls with our own outboard motors. This comprehensive approach, infrastructure and environment are what supplement the Jin-Ki Kanno behind Yamaha’s FRP boat hulls.

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