Surviving Three Days in 68ºF Water

In April, we reported that a New Zealand diver lost sight of his charter boat and drifted three days in 68ºF water before he was rescued. Robert Hewitt, 38, a former NZ Navy diver, explained how he survived his 30km drift up and back through Cook Strait in a conversation with Dave Moray, editor of Dive New Zealand Magazine. This is a synopsis of the conversation.

“At the end of my first dive,” said Hewitt, “I indicated my position by holding my fluro-green catch bag above my head and was picked up. I didn’t have a safety sausage. I have never dived with one.”

However, surfacing from his second dive, Hewitt saw his charter boat Shock Wave (from the Manawatu Dive Centre) in the distance. He lifted his catch bag and blew the whistle on his BCD. “I was down current and down wind in a half meter swell so it was difficult for the guys to see or hear me. The waves were getting higher so I ditched my weight belt.

“I was thinking ‘okay, I’ve still got the BC and the regulator and the bright orange cylinder, an excellent visual aid. It’s got 70 bar (1015 psi) in it that could be useful. The inflated BC gave me support when lying on my back. I decided to keep these items.”

When a search plane appeared, “I held up my catch bag open wide in the hope they would see the fluro-green color. I also grabbed my knife and tried to reflect light into the pilot’s eyes.” After the aircraft’s second pass, “I rolled over on my stomach so that the orange cylinder was more visible.” However, the pilot never spotted him.

As the current swept him north, Hewitt decided not to try to swim to land, “though it was killing me not to swim. The first thing about sea survival is don’t expel any more energy than necessary. To swim, I would need to ditch my BC, regulator and cylinder, which I was reluctant to do.” Instead, he lay on his back to conserve energy. “I was still getting pushed out and it took some strong thinking to convince myself that this was the correct plan.”

Hewitt recalled his Navy training, which had included spending the night at sea in a life raft. “The course was about conserving energy, keeping yourself in the huddle position (on back, lift knees up, put arms underneath the armpits and go with the current). I knew my body’s heat exit points: head, crotch, feet and underneath the armpits.” Dr. Simon Mitchell, a columnist for Dive New Zealand points out that shipwreck survivor stories include tales of others who simply became exhausted and essentially allowed themselves to drown.

Once he accepted that he would be drifting through the night, Hewitt recalled, “I yelled to my loved ones and that gave me a mental picture of them. It gave me hope.” He prayed to God and to the Maori gods of the sea for comfort. “It seemed that everything was all right. Whatever pathway I would take, whether I would survive or die, everything would be all right. That was the defining point right there, because I was happy within myself.”

During the night Hewitt realized that he sapped energy when he moved his legs. “The only thing I could do was lie on my back, cross my feet, keep my mask on and nod off to sleep – power napping! I’d wake up because my mouth would be open and water would slam into my mouth and wake me. Those power naps got me through the night. When I saw the sun come up Monday morning it was a joyous moment because I had conquered my worst fear. I’d got through the night and was still alive.”

On the second day, he began eating the crayfish and sea urchins he had taken during his dive. “During scattered showers I lay on my back and opened my mouth to catch what water I could. I had to take my mask off, turn it upside down and hold it up to grab whatever water I could, then tip it into my mouth. I started squirting/ purging the regulator into my mouth from a distance because I knew that there was moisture in the air. I had learnt this from the Navy.”

As the day warmed up, Hewitt said, “I could feel myself dehydrating quickly. My body was starting to go into shock because of the heat and energy I’d lost. I knew I had to cool off and keep active so I took off my diving hood and my gloves and put them in the BC pocket. I then took off my BC, then my jacket. I lay on the BC trying to hide my face from the baking sun. I decided to dump my regulator and cylinder that had only about seven bar (100 psi) left. I filled the BC as much as I could and then dumped the rest. As soon as I’d let it go something inside of me said ‘get it, get it!’ but it was too late.”

When he awoke on the second day, Hewitt knew, “I had to keep my toes and fingers moving because if they stop moving the body would shut down the extremities and look after the main core. These were the little things I learned on the parade ground when standing still for long periods. It stops you from fainting!”

When immersed in water, normal physiology works against you, says Mitchell. The cold (which constricts blood vessels in the limbs) and the loss of a gravity effect (which normally causes blood to pool in the legs) meant that most of the blood volume is ‘squeezed’ into the central circulation. One way the body regulates its water balance is by sensing a stretch of central blood vessels and the heart chambers. With blood shifting into the central circulation, these stretch reflexes become activated, telling the brain that the body has an excess of fluid in the blood vessels. Subsequently, the brain provides less stimulus to the kidneys to conserve water and they produce more urine (why one always wants to pee during a dive). So, an immersed diver dehydrates faster than someone who simply does not have access to drinking water.

Beginning to hallucinate, Hewitt took off his hood and gloves “to feel the cold water – trying to stay with reality.” The straps of his Apollo Bio-Fins dug into his Achilles tendons. “I couldn’t handle it anymore. As soon as I chucked them away I knew I needed them so I swam after them and put them back on. I didn’t put the straps on… and they came off my feet – lost.” (After he was rescued, he needed skin grafts to repair the damage.)

Feeling delirious and disorientated is consistent with a core body temperature drop to 32C – 33C (down from the normal 37C). A further loss of two or three degrees would have resulted in unconsciousness and drowning. This would have happened quickly because Mr. Hewitt removed his wetsuit top in his confused state.

Because of his Navy training, he did not make the error of drinking sea water, which contains salt at a high concentration. The body actively defends how much salt it carries, so the kidneys excrete excess salt. However, kidneys are not good at concentrating salt in the urine, so to excrete seawater salt, the body adds water from its own body reserves to produce urine dilute enough for our kidneys to handle. By drinking sea water we lose more water than we gain!

Because an immersion victim becomes progressively dehydrated, he can develop catastrophically low blood pressure and cardiac arrest if pulled from the water by his shoulders in the upright position. The sudden gravity causes blood to redistribute to the legs suddenly. Luckily, Hewitt was rescued by old buddies, professional naval colleagues, who understood this and kept him horizontal.

Hewitt says three things helped him survive: his love for his family and fiancé, his respect for the sea, and his Navy training “and the core values the Navy teaches.” His advice to others who might find themselves adrift: “Have confidence in yourself, your ability and don’t panic. Stop, take a breath and assess every situation as it comes.”