Some people are blessed with the gift of always knowing exactly where they are in relation to anywhere else. Like migrating birds they have the uncanny ability to find their way from point A to point B without the need to study a map or ask for directions. Even underwater and in poor visibility they rarely need to consult their compass before navigating a direct course back to the boat or exit point.
Such people make great dive buddies. Regrettably it’s not a talent that’s easily acquired. For most of us, successful underwater navigation depends upon constant practice and our skill in following a compass heading; the ability to gauge the strength and direction of any currents; how well we can remember features of the underwater seascape – and even what the hull of the dive boat looks like when viewed from beneath the surface!
I’d never given much thought to this aspect of underwater navigation when diving from a vessel. Granted, I may not always have surfaced exactly back at the boat; but by guess and by God, (and always allowing my dive buddy to take the lead – and all of the blame – when I have been off course) I’ve usually managed to avoid the stigma of being branded as an incompetent navigator. Until recently, that is.
It was the first dive of a four-day liveaboard trip to dive the Ribbon Reefs north of Cairns, on the outer edge of Australia’s Great Barrier Reef. Arriving at the ‘Cod Hole’ in the early morning and anxious to get into the water, my buddy and I paid little attention to another Cairns vessel moored some 350 metres away.
“Follow me, Huw.” I cried as I leaped from the boat’s side. “I know this site like the back of my hand!” Huw, then on holiday from the UK and who had never dived the Great Barrier Reef previously, seemed happy with the arrangement.
In warm, tropical waters with visibility at 30-plus metres, we swooped through gullies and swam between coral heads among clouds of purple and gold reef fish, damsels, angelfish, parrotfish, whitetip reef sharks and the giant potato cod after which the site is named.
Drifting across the tops of shallow corals towards the end of the dive, I saw a boat’s ladder above me. Attracting Huw’s attention, I tapped my watch, pointed to the hull above our heads and indicated that we should ascend. He urgently scissored his hands in front of him in a, ‘no’ signal. Grasping the bottom rung of the ladder and removing my fins, I again indicated that he should ascend. He shrugged in resignation, made his way to the ladder and surfaced just in time to hear an amused crewman lean towards me saying, “You’re on the wrong boat, mate!”
Mumbling obscenities and blushing furiously as I put my fins back on, I looked towards our vessel ying some distance away. Nobody appeared to be pointing in our direction. “We’ll swim back on the surface”, I whispered to Huw, “and just tell folks onboard that we finished our dive and surfaced in this general vicinity.”
It was a good face-saving plan. And we could have got away with it if the skipper of this other vessel – an old acquaintance – hadn’t chosen that precise moment to look over the stern and recognise me! “Bless my soul, Strikey! Trying to jump ship again, eh?”
Some people rise to a challenge. Huw proved such a person. “We’ve just carried out a below-the-water-line inspection on your hull and everything appears to be OK. Will you be paying by cash or cheque?”
The splashing of our fins as we pounded our way back to our own dive boat drowned out the skipper’s cheery farewell.
“Well Huw.” I said later. “I hope my little charade proved helpful in demonstrating the importance of good underwater navigation techniques. Understanding tides and currents and how to use the compass properly are fine, but a good diver should also be able to rely on natural aids to navigation like sand-ripples, light shadows, and the effect of tidal flow on kelps and seaweeds. As I did on that last dive.”
“I guessed that when – knowing that we were aboard a single prop mono-hull – I saw you about to board that twin-prop catamaran.” He said with a straight face.
“Right! Well now that you’ve seen how it’s done, I’m going to let you navigate on all of the other dives. Just remember: Practice makes perfect”