Handling the pressure, divers tested

Jessica Gillies
Staff writer
July 31, 2006

Four men dressed in shiny gold-coloured jumpsuits sit quietly in the white recompression chamber at Fleet Diving Unit (Pacific) and give the “thumbs up” signal.

Their clothing matches the cushions in the sealed chamber - a large tube with portholes.

“Diving,” says a disembodied voice over a speaker.

Although nothing looks different from the outside, the pressure in the chamber begins to increase at a rate that simulates a descent into the ocean at 30 feet per minute.

One of the men makes the “thumbs down” sign.

“Stop,” says clearance diver LS Shawn Goodine, who’s in the chamber as an inside tender to make sure the three men are comfortable and following directions.

Once the man who gave the “thumbs down” has cleared his ears, the descent to a simulated depth of 99 feet of seawater continues.

Three of the men are combat engineers from 1 Combat Engineer Regiment at CFB Edmonton. They are candidates for the combat diving course along with two other candidates at Fleet Diving Unit (Pacific) facility in Colwood. The five need to complete their pressure tolerance test to ensure they can clear their ears and sinuses to a depth of 99 feet of seawater, which is heavier than fresh water due to the salt content. The pressure tolerance test is a requirement for all members of the CF who want to become divers.

“It’s a controlled environment for us to be able to see if an individual is able to go under pressure,” says LS Goodine.

&ldquoAlthough they’re healthy, physiologically, everyone is different,” says diving technician Dan Bewsher, a former clearance diver. “This saves us from putting them on course when they’re not going to make it.”

The gold jumpsuits are made of non-static, non-flammable material called Durette, explains repair chief CPO2 Mark Oliver. The jumpsuits keep contaminants out of the chamber and avoid static electricity.

Before they climbed into the chamber, the candidates were briefed on what to expect. They were told to breathe normally and warned the compression of air on descent causes the chamber to get hot. While travelling back up, the air gets cold.

They were told they might feel like they were drunk due to nitrogen narcosis, which divers sometimes experience. When they dive their bodies absorb nitrogen, which can have a narcotic effect on human physiology.

They were instructed not to talk during the dive, because the dive supervisor and chamber operator outside the chamber needed to hear only the tender when the chamber was simulating diving or travelling up to the surface.

Cpl Marty Gratrix, one of two qualified combat divers who accompanied the candidates from Edmonton, says being in the recompression chamber feels just like being on the earth’s surface and just like diving.

“As long as you’re clearing your ears properly, it feels just like sitting here,” he says, gesturing around him. But, he adds, it’s painful if you can’t clear your ears.

“It felt like when you’re going up in an airplane and your ears pop, but the popping doesn’t stop,” said combat diving candidate Spr Chris Banko after the test.

“It heats up really fast; you can really feel the heat. It felt pretty normal. Your voice is all squeaky. I didn’t really know what to expect,” said candidate Lt Kurt Grimsrud.

The squeakiness is because the density of the air changes in the chamber, so it sounds different going across their vocal cords.

The test is part of a two-week preliminary selection process run by qualified combat divers to select the best possible candidates.

Candidates can fail the test if they can’t equalize their ears or sinuses, which can happen for reasons such as having a cold or problems with their Eustachian tubes, which are responsible for pressure equalization and connect the back of the throat to the middle ear.

“It’s not hugely common, but it has happened before,” says Cpl Gratrix. “Some just cannot clear their ears.”

In the end, all five combat diver candidates were successful at the pressure tolerance test.

« Previous Story | Next Story »