Sinking is usually unplanned  ... even in the EU [actual emergency radio call transcript below]

"Mayday, mayday, mayday"

"Zis iz zee German coast guard Vhat iz your emergency"

"We are sinking"

"Vhat are you sinking about?"

Jaxson:

 

Bottom line is you probably stand a better chance of survival if you don't fall into the cold water in the first place.  ie don't sink to start with.