It was 6pm when an unusual rainbow-colored boat, made of recycled plastic waste and discarded flip-flops gathered from beaches and roadsides, dropped anchor off the beach at Mtwapa, near Kenya's coastal city of Mombasa.The 9-meter-long dhow, "The Flipflopi", was sailing south along East Africa's coast to raise awareness of the threat plastics pose to the oceans, said chief boat-builder and captain Ali Skanda.Beaches and marine ecosystems have been badly affected by plastics, Skanda said…