An open planing boat of fair dimensions, with a good amount of space on deck, with enough room to fish, take a sunsplash, have a dive, or simply have fun; she’s powered with an outboard that allows you to travel quite fast, at a reasonable price, and with a set of plans suited to be built by an homebuilder with plywood , solid wood and epoxy.
These are the main features of this plan, which has seen the light some weeks after is bigger sister “Crispy 650” to fill the gap of an open planing boat that can be powered with a cheap 40 HP engine , with good performances and a roomy versatile hull.
Anyway the brotherhood between Crispy 520 and the bigger Crispy 650 starts and ends in a general common look and in the boat building system. For all the other aspects, hull, load evaluations and weights settings, performance analysis, we started from a clean sheet, since I don’t like the downscale or upscale operations, a quite common practice , which not always lead to good boat quality.
So I designed a new hull, with a stern deadrise of 17.5 degrees, a good compromise between top speed and seaworthiness on a seaway; the hull topsides are quite high in bow area , to give a decent repair from sprays (and save an expensive stainless steel handrail, if you want…). A hull ready to be planked with plywood sheets.
The boat hull is based on a structural grid made by 12mm marine plywood bulkheads, linked with solid wood stringers, all glued with epoxy resins, and a sturdy laminated plywood stem glued to a solid wood backbone which runs from bow to stern; the planking is in plywood (12 mm for the bottom , 10 mm for other surfaces), glued to the structural grid, with biaxial glass tape laminations were extra stiffness or chafe resistance is required. All these makes a really sturdy and stiff hull with a weight (without engine) of 420 kg .
Crispy 520 plan represents the entry level for a homebuilder, but she’s a “real boat” , not just a tricky toy to practice with plywood & epoxy.
TECHNICAL SPECIFICATIONS
| Hull Lenght: 5,20 m |
Project displacent: 950 kg |
| Maximum beam: 2,16 m |
Top speed at project displacement with 60 HP engine: 31 knots |
| Draft with engine: circa 0,65 m |
Maximum displacement: 1200 kg |
| Powerplant: single outboard 40-70 HP |
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| Hull weight (no engine): 420 kg |
Hull weight with engine (40 HP 4T) and accessories: about 550 kg |
| Fuel tank: underneath the deck, commercial one, from 60 to 80 liters |
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Crispy 520 on the water
Simple Guide to Epoxies
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