A team of 6 scouts plans to cross a lake on a raft they designed. The scouts have wooden beams with an average relative density of 0.80. The beams measure 30cmx30cmx3m. The average scouts' mass is about 65kg and for their safety, they want the top of the raft to be at least 3cm above the surface of the water. How many beams do they need to complete their projects successfully?