These objects were designed for the Thingiversity Science Challenge: Make It Float. The challenge consists of the creation of a 3D model of a boat or other floating object. To increase your chances of winning, 3D print your model and then test, redesign, and retest to optimize the amount of weight your boat can support using coins in your local currency, and this is our story: The best an optimum solution for this contest is a box, with dimensions a multiple of the coin diameter, and as high as your printer limits. But a box is hard to push through the water... But we wanted to reproduce a real ship for this contest, so we choose a catamaran (double hull ship) that could take the coins with style... and certain speed. The real ship is named Zephyr and is a wind turbine service catamaran, that is able to run at 26 knots. A catamaran hull presents better speed and stability for carrying load (including coins). See our video of the prototype advancing in the water with a slightly touch. We starded designing from the scratch, using Rhinoceros for modeling the hull, based on pictures and technical drawings from magazines (see pictures). This took a veeeeery long time. We also played some CFD (computer fluyd dynamics) in order to check how the ship will behave in reality at 26 knots. (See the coloured pictures that show the wave pattern of the ship). From these calculations you can obtain the size of the motor that you are going to install to get the speed. We obtained a good aproach with the real power onboard according the magazines. That means that our design was similar to the one of the real ship. Regarding printing, we started with a one piece prototype with the horizontal deck paralell to the printer base, Cat_Zephyr_1.stl. We had problems printing such a large plane deck that made the ship a non-watertight ship (bad idea for a ship), so we produced a slightly smaller hull, printed in vertical, Cat_Zephyr_2.stl. That presented a better finnishing but it was too heavy to carry (with or without style) some 5 cents euro coins. https://www.youtube.com/watch?v=IK4HD882nTA https://www.youtube.com/watch?v=-I7eEMudPU8 Based on these two previous prototypes, for the final solution we have constructed a two pieced hull, hollow in its side hulls so coins can fit inside. The model is about 28 cm length (the key is that the weight is scaled with the 3rd power of the scale, so if you construct a ship that has double dimmensions, you will have eight time more volume that the previous design. Our final design weigths 198 gr, and is able to carry a load of 5 cents euro coins of 723 gr before sinking. It can advance well in water with a weight of 803 gr (with 605 gr of coins inside). https://www.youtube.com/watch?v=Xl3zDsv7pgs Thank you to the people of the model basin of the Technical University of Madrid (CEHINAV). The water basins and electronic weight are from this laboratory.Software: Repetier with slic3r. zephyr1.stl and zephyr2.stl: can be made at 0.2 mm, even 0.1 mm, 3 shells, Infill 15%, speed about 40 mm/s zephyr3.stl: The bigger version needs more than 8 hours with 0.2 mm, so we used 0.3 mm, 2 shells, infill 10 %, speed about 44 mm/s. No support surfaces are needed for the three prototypes.