If you're able to catch your breath — which is difficult enough to do — the second phase of cold water shock is cold incapacitation — which causes your muscles to eventually stop working.
"In 50-degree water, you might have as little as ten to 15 minutes of
manual dexterity, where you should try to get back on your boat or
signal for help in some way. If the water is cold, it's only a matter of
time before you lose control of your arms and legs," Newman said.