QUOTE
Once in the freezing water, hyperthermia would have set in fast, leaving them with little to no energy to swim or pull themselve onto an iceberg.
quite true. the temperature of the water in the North Atlantic ocean would be about 10 degress or chillier. once in, you would go into shock, hypothermia would start to set in, leaving no energy to pull yourself onto an iceberg.
that theory assumes anyway that the iceberg was the correct shape for pulling oneself onto it. pictures of icebergs i have seen look impossible for you to pull yourself onto them while being in the water.
and exactly HOW did they survive for a week with no water? (ocean water is salty, leading to dehydration, ice from the berg would need to be melted)
just some thoughts to ponder...