I WANTED TO FIND OUT about divers’ instincts for direction and depth. How accurately can we hold a direction, judge a turn, guess a depth or maintain a depth with no instruments and no reference points
Many of the happy Tek-Campers and a few innocent visitors at Vobster became willing and ever-so-slightly coerced volunteers for a few simple exercises. These are also exercises you can try for yourselves to liven up your off-season trips to inland sites; I have added some safety notes about that in the panel below.
First off, an outline of the exercises, then I’ll get into the results.
Each exercise is suitable for buddy pairs, where one diver does the exercise and the other acts as a buddy, monitors the exercise and provides safety without intruding on what actually happens.

Having a go
The following little exercises are things you can try for yourselves next time you’re at your local inland dive centre.
The instructors and Tek-Campers who tried these all thought they were exercises worth continuing with and practising. Not as techniques in their own right, but as exercises that help to develop skills in buoyancy, trim, stability and general awareness.
If you do have a go, however, please bear in mind a few safety considerations.
Only ever do the descent and hover exercises at the start of a dive, when you have no nitrogen loading. Do not do them at the end of a dive, where ascent speed and depth are critical.
Bear in mind that while the buddy is watching the diver doing the exercise, the diver doing the exercise is, by the nature of the exercise, not watching the buddy.
On the navigation exercise, the diver should not zoom off in a straight (or random) direction so fast that the buddy can’t grab him if necessary. If you can’t resolve this, you need a team of at least three: one to do the exercise and two buddies to look after the diver and each other.
No matter how good you get with practice, never depend on these exercises as a replacement for a line and a depth gauge to manage decompression stops.

1a. Straight-line navigation
The objective is to swim out in green (blue) water at a fixed 3m depth with no visual reference – no bottom in view, no lines, and your buddy behind in the “blind spot” towing an SMB.
A dive computer is used to keep at a fixed 3m depth and check time (but not one with a compass display, as that would be cheating).
The starting direction is ideally taken from a straight-edged fixed object, or at a push from
a compass bearing (but after starting, the compass has to be put away).
In Vobster we used the side of the confined-water training area to give an initial direction.

1b. About-turn
The diver swims out for one minute in a straight line, guesses a 180° turn, then swims back for one minute. After the return minute, the diver and buddy surface.
The buddy tows an SMB, and where they actually go is recorded by the shore cover, ideally with a video clip on a digital camera. If the navigational guesses are perfect, the diver and buddy end up exactly where they began.

2a. Descend to 5m
The objective is for the diver to descend in green water with his back to a descent line and stop at 5m, with no dive computer or other means of measuring depth.
The buddy stays behind the diver so as not to intrude on his descent, notes the depth at which he actually stops, and makes sure he doesn’t go dangerously beyond the 5m target. The descent line provides a safe visual reference for the buddy and, just by turning round, for the diver.

2b. Maintain a 5m depth
The buddy now re-positions the diver at exactly 5m. The diver turns his back on the descent line and his buddy, and simply hovers at that depth for one minute. The buddy again records the depth at which the diver actually is, and stops him from drifting dangerously deeper.

How do you think it would go
Before going into the results, a few words about how I thought it would go. Perhaps you can pause at this point and speculate for yourselves on how things would turn out.
I expected the results of all the exercises to be some sort of random distribution. Some divers would hold a line better than others, but there would be random variation of how well they would hold it. Turns would be randomly varied about the target 180°.
There have been some experiments on dry land to see how people walk in a straight line with no reference points. These have proven that the walkers circle away from their stronger leg. So if right-handed, they circle to the left. Perhaps divers would do the same.
I thought that some would guess a 5m depth more accurately than others, but that there would be a big random variation about that depth. With maintaining a depth, again I expected a big random variation.

The actual results
First off, I didn’t have a random set of lab rats. My rats were nearly all Tek-Campers who had been intensively practising skills, especially buoyancy and trim, for the previous few days before trying these exercises.
They were all well dived in and dived in for the conditions in Vobster. It was a rainy, cloudy day, so there were no hints from the sun.

1. Straight-line navigation & turn
Overall, I recorded 14 runs, which can’t be construed as the quality of science to submit for a PhD, but trends quickly emerged that would be good enough for pub-quality science.
The results were binary. Divers could either hold a straight line or they couldn’t. They either held the straight line as closely as I could tell, or their course was all over the shop. There was no intermediate result of “almost” or “not quite”.
Right- or left-handed divers, it made no difference. There was no discernible right or left bias within the one minute they were swimming each leg of the exercise. Perhaps this would show on greater distances, but not within these limits.
Fin-kick style made no difference, either. Divers using flutter-kicks or frog-kicks both either held a line, or deviated wildly.
With those who could hold a straight line, invariably they over-turned by a small amount and ended up 2 or 3m to the side of their starting point. With those who couldn’t hold a straight line, sometimes it was hard to tell where they actually made the turn!
The good news for those who wandered is that the technique can be learned. A few divers made two runs, one flutter-kicking and the other frog-kicking. One pair, after observing each other as buddies, steadily improved over the four runs they made as two runs each.
They watched each other and adapted their technique so that the first diver’s second run was straight, but with an inaccurate turn. The second diver’s second run was spot-on.
The technique that gave the best straight result was to be in a good horizontal trim with hands joined forwards.
Some divers commented that they used their own hands as a target towards which to swim.

2. Guess and maintain depth
All the laboratory rats in these exercises were Tek-Campers and, with the assistance of Tek-Camp instructors Martin Robson, Paul Toomer and Mark Powell getting their groups to have a go, I had 17 sets of results to analyse for guessing the depth, and 13 sets for the subsequent hover.
We are still in the realm of pub science, but getting closer to my Nobel Prize for diving.
Rounding to the nearest half-metre, more than 50% of the divers nailed it to 5m and only four were more than 1m out. None of them was more than 3m out on guessing their depth.
Among the successful divers, their comments on how they judged the depth included “the second time I cleared my ears”, “suit squeeze and inflation”, “the level of light” and “water temperature”.
The second part of the exercise, placing a diver at 5m and seeing how accurately he could maintain the depth, was less consistent.
After one minute, only one diver stayed spot-on at 5m. Three drifted up to 3m and then stabilised. The rest either slowly descended or rose slightly before slowly descending, in all cases but one realising this and stabilising at between 6m and 9m.
The one remaining diver drifted up to 3m, then down to 14m before being stopped by
his instructor.
The general trend to ending up deeper may have something to do with diver’s eyes becoming accustomed to the light level, but this is just speculation on my part.
The most interesting result here was a variation that Paul Toomer introduced.
He placed a team of three divers facing each other at 5m with no reference point except for each other, and no visible instruments.
They stayed spot-on at 5m by using each other as reference points.
The trick, as the Tek-Camp instructors all explained to their groups, is to develop a fine level of awareness that is almost subconscious. Elements such as light level, water temperature, ear-clearing, breathing rate and suit squeeze all give clues.
In particular, for the hover exercise even the minutest variation in suit buoyancy needs to be noticed and corrected for by breathing in or out to descend or ascend and regain stability.
At any point, if you find you need to dump or add air to your drysuit, you have moved too far.
When I say “dive the Force, feel the Force”,
the force in question is water pressure.

For more information on Vobster and Tek-Camp, visit www.vobster.com and www.tekcamp.co.uk