In SR4 pg 119 it has the rules for floating in water and says you need to make a Body test using modifiers from a table but it doesn't actually say how many hits you need. Will it just be a single hit required?

sounds reasonable. floating is really not very hard.

Unless you have bone density bioware or something. But yeah, agreed, if it doesn't say anywhere, I figure it is just one hit.

Burn edge for a critical float, spend one round standing on the surface of the water.