Week 7

The construction of the boat was completed.  In order to do this, the other pontoon of bottle needed to be created and the base constructed.  The first step was to collect more bottles.  This was done by visiting a view houses right before the recycling truck came.  This did not take long due to the fact that plastic bottle were abundant.
There were some changes made during the construction that differs from the original design.  The original design called for cardboard to cover the top.  We did not think this would provide enough support.  We attached a half inch thick piece of ply-wood instead of the cardboard.  Before adding any weight we noticed that it was too rigid and starting to crack from all the weight.  Two more two by fours were adding going across the base to provide spots to hold the weight of a person.  With this attachment the strength of the ply-wood was not needed.  We could have switched back to cardboard but left it on so we could provide more weight for testing.
The testing of the boat was held in a pool.  The first attempt we applied two people to the raft.  The raft held up but was very unbalanced.  This was due to the bottles collected in the middle of the pontoon causing the raft to act like a seesaw.  We solved this by applying rope around the middle of both pontoon forcing the bottles to travels the four edges.  This balanced the boat much better.  Another person was then adding to show that it can hold its goal of 450 pounds.  The three people totaled almost 500 pounds.  We concluded that any more weight added would cause the raft to become very unbalanced.

Figure 1: The boat with the added rope around the pontoon and 2"x4"s across the base.

Figure 2: Raft holding almost 500 pounds and staying afloat.