Conclusion

CONCLUSION

The testing stage wasn’t as successful as we hadhoped as we only managed to ascertain one true position of the floats and a volume of water added at which the model was stable. After the seal broke around the bottom, we couldn’t test further. However, the results that we did obtain have led us to the following conclusions in relation to our specification.

Assessment of Buoyancy

The model itself is very buoyant. It floats much higher in the water than was initially expected. This has helped as we have not needed to add any means of flotation. Instead, we have had to stabilise it. However, left to its own devices, its buoyancy is ambiguous as it isn’t buoyant once it has fallen over and began to sink. If anything, the buoyancy has also caused problems as we have had to add mass, in the form of water, to help in sit lower in the water to make it more stable. The real tower will therefore fall victim to the same flaws in the design. It will sit high in the water with a strong chance of toppling over.

Assessment of Capability to be Towed

Towing the unit will require incredible skill. The pontoons that we have added have helped somewhat in stabilising the unit but have not been totallyeffective. The pontoons added, were streamlined and so would create little drag compared to some of our previous ideas for stability. The pontoons are also very easy to steer. They would naturally follow the tow rope and so could be manoeuvred easily. We had 2 tow ropes initially but then decided to have 4, 2 on each pontoon. One of these was positioned above the water’s surface, and the other was below. This helped to stabilise the two moments created and caused equilibrium at the towing force. This made the towing process much easier. However, the pontoons didn’t prevent forward and back swaying motion and so we believe that for the real construction, the pontoons will have to be at least 25%longer. They already seem to stop sideways swaying but when the ropes are pulled with anything other than a small force, the model topples forward in the direction it is being pulled. Also for the full size base, towing would need to be completed by at least two vessels as the construction would need to be pushed and pulled into place at the site that it will be sunk. If only one boat is used, then there would be no control over pushing the model away from the boat.

Assessment of Resistance to Inclement Weather

This was hard to accurately replicate for our model. For example, in a scale model situation, a small wind to humans is almost gale force winds to the model. The small natural ripples in the water were relatively large waves. We did however, use a rugby ball to simulate larger waves and to some degree, the model did remain stable. The stability would be improved considerably once the pontoons have been made larger. We would advise however, that when the real base is launched, it should not be done in bad weather conditionsas this would add to the unstable nature of the tower. The pontoons are essential in minimising the risk but if the risk factor is raised, even more strain is placed on the tower.

Assessment of Self-Righting Ability

Vertically this has excellent results. Even though the large base creates large disturbance in the water, the spring back buoyancy of the tower exceeds this. Thus the vessel can absorb extensive vertical movement. However, the stability issue arises here as well. The model did not return back vertically after being pushed down. It came back at an angle and so this created a turning moment which collects momentum and causes the tower to topple. This would be helped a lot by the longer pontoons as they should keep the model level whilst it is low in the water. This current instability has led us to conclude that our design has failed on this account.

Assessment of Rate of Sinking

Due to the seal breaking under stress, we were unable to test this. However, the amount of water that is placed into the tower will equal the amount of water displaced from its original height in the water. If the amount of water is monitored, then you can determine the rate of sinking and predict how long it will take. However, this will depend entirely on the size of the pump, the thickness of the hose used and the weather conditions. If it is raining, then the unit will take in water in the top. This will lead to an inaccurate prediction of the timings.