Cold shock can kill long before hypothermia. When a person falls into water less than 15°C the first reflex is to gasp and then to hyperventilate making it extremely difficult to hold your breath. The heartbeat may become very fast and irregular during this time. There is a high danger of drowning if the head is not kept above water. It may take several minutes to regain control of breathing and become able to climb back aboard if this remains possible.

You lose strength and coordination quickly in cold water, typically in 10 to 15 minutes. It is important to inflate lifejackets and rafts, and set off EPIRBs quickly for the best chance of survival and rescue. Prepare flares and signals next, so they are easy to access and deploy when help arrives 

Activity such as swimming will increase heat loss. Hypothermia commences when the body core temperature reduces, typically within an hour of immersion.

If you fall into cold Victorian waters you will generally have:

• 1 minute to get your breathing under control and keep your head out of the water

• 10 to 20 minutes of useful movement in which to get out of the water to prepare for rescue

• 1 to 3 hours before you become unconscious due to hypothermia.