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Model testing the "Pandora" The full sized boat, the - Pandora 3.54 m (11' 7" ) is a 'Sharpie' hulled sailing dinghy. Principal dimensions of the model: L.O.A. - 880 mm (34-5/8"), Beam - 370 mm (14-1/2"), Sail area - 0.345 m2 (3.71 sqft). Scale: 1 : 5 (20% full size) Hull construction: I use cardboard of near scale thickness. The board is prepped by sealing with polyester resin on both sides. The hull panels are plotted to scale and glued to the sealed board using PVA glue. After cutting with a fine toothed blade in the jig saw, assembly is stitch and glue. Thickened polyester resin fillets by themselves are ample strong enough for model construction, so glass is omitted.
	Bulkheads and transom are cut from hardboard and sealed with polyester. The finished model is painted using vinyl high build primer to further waterproof. Daggerboard and rudder are plywood, shaped and sealed. The sail is cut from old polyester (mylar) drawing film, with corners reinforced and fitted with eylets. She is ballasted and trimmed with small lead weights to have the correct scale displacement. The radio control operates only the rudder, mostly because I have not yet found a way to incorporate a suitable sheet control servo. To get around this the sail is sheeted for a close reach. This way she will sail downwind too even if a lttle inefficiently.
Foam buoyancy was added to prevent loss of model and radio control equipment in the event of a capsize. So far this feature has luckily not been put to the test, even though we took on some water occasionally in gusts. Testing radio controlled scale models is admittedly not as high-tech and serious as testing in a towing tank, but it nevertheless provides valuable and low-cost feed-back on how a particular boat performs. Handling under sail and balance of the model is directly comparable to the full size boat even if wind and boat speeds and stability are very much subject to scale.
"Pandora's" model has passed its sailing tests with flying colors, just like "Pixie", "Pinta" and "Swift" before. In fact sailing the models of these boats has proved far more enjoyable than I expected and I always have to force myself to pack up and return home after such tests. To put the usefulness of the model tests into perspective: the full-size "Pinta" exhibits the same fine sailing qualities as the tested model. For the equivalent of three evenings work building the model and an afternoon's enjoyable testing, I get a lot of confirmation and feedback on the design and construction and this benefits you when you buy any of my plans.

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