Winter Diving

Question:

Winter Diving in board shorts only, in 17 or 19 degrees C water to depths of up to 45 metres with bottom time of up to 70 minutes (at shallower depths) in the waters off Rottnest Island, Perth. I am wondering if there are any associated medical risks, such as:

- Cooler core body temperatures (from diving in boardies). Does this lead to a greater absorption of Nitrogen per minute of exposure?

- Coming back on-board and having a hot shower (which I don't) will increase risk of DCI, however warming up slowly with dry clothing and a wind chill free environment - like the wheel house of a vessel - is this likely to still pose a risk of DCI (Narcosis or other) and how does the risk of DCI increase with Hypothermia?

Answer:

The obvious risks of diving in board shorts only are of hypothermia, which can lead to poor decision-making, poor coordination, loss of muscle strength.

Hypothermia can also predispose the diver to DCI.

Nitrogen is more soluble in cold tissue so the tissue can easily hold more of it. Any increased risk depends on when the diver becomes cold. If they get cold later in the dive they will have a fair bit of nitrogen on board and then blood circulation reduces with the cold and delays off-gassing during ascent.

A hot shower is a bad idea as suggested as excess nitrogen may be released from body tissues too quickly due to its reduced solubility in warmer tissues and the increase in blood circulation. Slow warming will reduce the chances of DCI but won't eliminate the risk.

Basically, it's just not good sense to dive in boardies in those temperatures