We didn't know exactly when the inmates launched their boats, or their precise starting point, and so we decided to release 50 'boats' every 30 minutes between 20:00 and 04:00 (11 p.m. and 4 a.m.) from a range of possible escape spots at Alcatraz to see where they would end up, we added a paddling effect to the 'boats,' as we assumed the prisoners would paddle as they got closer to land.