EPS@ISEP | The European Project Semester (EPS) at ISEP

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report [2013/06/12 16:47] – [6.2 Structural] team3report [2013/06/12 18:51] (current) – [Appendices] team3
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 *An important remark to make is the fact that in this test the weight of the fibreglass hull has to be included. We placed the hull in the water were it will cause a force on the surface; then we added water into the hull to enlarge this force. 16,50 kg has to be added to the 2 results. *An important remark to make is the fact that in this test the weight of the fibreglass hull has to be included. We placed the hull in the water were it will cause a force on the surface; then we added water into the hull to enlarge this force. 16,50 kg has to be added to the 2 results.
  
-Because the results of the practical test differ from the results of the calculations, we can conclude that the shape of the hull is not a perfect hemisphere, it is bigger. Because we want to obtain the highest safety level as possible, we will make further calculations with the lowest masses: 56,00 kg and 88,30 kg.+Because the results of the practical test differ from the results of the calculations, we can conclude that the shape of the hull is not a perfect hemisphere, it is bigger. Because we want to obtain the highest safety level as possible, we will make further calculations with the lowest masses: 56,50 kg and 88,30 kg.
  
 Now we calculated the ultimate maximum mass that can be attached to the fibreglass hull, we will take a look to the loads: Now we calculated the ultimate maximum mass that can be attached to the fibreglass hull, we will take a look to the loads:
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 The total mass of the loads, placed in the water, will be 44,20 kg. These loads will cause a force equal to:\\ The total mass of the loads, placed in the water, will be 44,20 kg. These loads will cause a force equal to:\\
 {{:x7.png?|}}\\ {{:x7.png?|}}\\
-Out these calculations we can conclude that the buoy will be buoyant and that we can add an additional ballast with a mass of 11,80 kg. If we add this ballast, the fibreglass hull will be submerged until the water level is exactly underneath the ”Saturn-ring”. +Out these calculations we can conclude that the buoy will be buoyant and that we can add an additional ballast with a mass of 12,30 kg. If we add this ballast, the fibreglass hull will be submerged until the water level is exactly underneath the ”Saturn-ring”. 
  
 Another important factor of the buoyancy is the stability. An object can be buoyant, but if it is not stable it can turn over. A floating object is stable if it tends to restore itself to an equilibrium position after a small displacement. For example, floating objects will generally have vertical stability, as if the object is pushed down slightly, this will create a greater buoyancy force, which, unbalanced by the weight force, will push the object back up. Rotational stability is of great importance to floating vessels. Given a small angular displacement, for instance due to a wave, the vessel may return to its original position (stable), move away from its original position (unstable), or remain where it is (neutral). \\ Another important factor of the buoyancy is the stability. An object can be buoyant, but if it is not stable it can turn over. A floating object is stable if it tends to restore itself to an equilibrium position after a small displacement. For example, floating objects will generally have vertical stability, as if the object is pushed down slightly, this will create a greater buoyancy force, which, unbalanced by the weight force, will push the object back up. Rotational stability is of great importance to floating vessels. Given a small angular displacement, for instance due to a wave, the vessel may return to its original position (stable), move away from its original position (unstable), or remain where it is (neutral). \\
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 **Table 6-6 Mass under the centre of buoyancy**\\ **Table 6-6 Mass under the centre of buoyancy**\\
-{{:table_6-6.png?200|}}+{{:table_6-6.png?200|}}\\
  
-We can conclude that, when we add a ballast of 11,80 kg, the point of gravity will be at the same height as the point of buoyancy, whereby we can say that the prototype will not be stable.+We can conclude that, when we add a ballast of 12,30 kg, the point of gravity will be at the same height as the point of buoyancy, whereby we can say that the prototype will not be stable.
  
 A solution for this problem is to add more ballast. When we add more ballast the fibreglass hull will submerge deeper. We can keep adding ballast until the water level is in the middle of the ”Saturn-ring” (the maximum mass we can add is 44,10 kg). The perfect balance between ballast and the depth of the buoy has to be determined with further tests. A solution for this problem is to add more ballast. When we add more ballast the fibreglass hull will submerge deeper. We can keep adding ballast until the water level is in the middle of the ”Saturn-ring” (the maximum mass we can add is 44,10 kg). The perfect balance between ballast and the depth of the buoy has to be determined with further tests.
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 {{:appendix_a._mooring_a_buoy.pdf|}} {{:appendix_a._mooring_a_buoy.pdf|}}
 +
 +{{::appendi_b_x-buoy_-_technical_drawings.pdf|}}

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