A GOOD FEW YEARS AGO, I rolled backward from the tubes of the club RIB and set out to explore the wreck of HMS Falmouth, leading a much less experienced buddy on his first open-water wreck dive.

We swam around the well-broken remains for an enjoyable 37 minutes before I signalled that it was time to end the dive and make a free-ascent in midwater. We broke surface within touching distance of the boat, to the utter amazement of my buddy, who demanded to know how I’d accomplished such a feat in rubbish vis and on a wreck best described as so much jumbled scrap, with no recognisable navigational references.
I mumbled something suitably modest, and otherwise kept quiet. The performance earned me a reputation for navigational excellence that I maintain to this day.
What I’ve never admitted before is that I remember nothing of the wreck, because I actually spent the entire dive with no idea of where I was, and desperately trying to find the anchorline so we could get back to the boat without a long surface swim. I gave that up only when our remaining gas supply suggested that being on the surface toot sweet would be a smart move.
Which brings me to the Strobo strobe made by Polish manufacturer GRALmarine.
This is a substantial piece of kit. It feels weighty and solid in the hand, like the sort of thing that you can depend on when everything else in your world goes Pete Tong, and you need a break.
True, there’s a whiff of the garden shed in the build quality and the printing of the graphics, but the unit carries the CE mark and the website claims that the standard strobe is tested to 150m, with a 300m tested unit available on request.
I had been sent a 300m unit, but the Editor told me that I didn’t have to take it that deep, which was good of him.

The Design
The strobe is an aluminium cylinder that measures 4cm in diameter and 13cm in length. It unscrews in the centre to allow you access to the supplied single 18650 battery. A charger comes with the strobe.
At one end of the cylinder is the lamphead, a clear plastic dome under which is a small three-sided pyramid with a single LED in the centre of each side (below).
At the other end is a substantial stub with a hole through it. Through this is threaded a length of bungee tied to a stainless-steel, single-ended bolt-snap.
The strobe turns on by simply screwing both halves of the cylinder tightly together, and turns off when you unscrew it a half-turn or so.
I like simple screw-to-turn-it-on-or-off kit. In my experience it’s the most reliable solution long-term. I know it’s possible to unscrew things so far that they flood, but the Gralmarine has a double O-ring seal to guard against that.
If you’re daft enough not to notice that it’s stopped flashing and you can stop unscrewing, that’s your look-out.
When you do turn it on, just make sure that you’ve either shut your eyes or are looking away. The output is 3600 lumens, and that’s serious illumination at less than arm’s-length, even under water.
The three LEDs flash five times, pause for a second, and repeat until there’s no more power in the battery. Flashing lights are far more noticeable then steady lights – just ask any cyclist who rides in the dark – and the pattern of the strobe certainly does the business. If you try it indoors in a small room, you’re begging for a headache.

In Use
You use the bungee and snap to fasten the strobe to the shotline a few metres above the wreck, and you can then enjoy the dive with a far better chance of finding the line when it’s time to begin your ascent.
The GRALmarine hangs vertically down so that the lamphead is correctly positioned for maximum visibility as you look upward, and those 3600 lumens pulsing away are easily seen, even in your peripheral vision.
The distance at which you’ll be able to see the light will vary depending on the vis and the relative illumination level at depth, of course, but vertical vis always seems to be better than horizontal, and by positioning the strobe above the bottom you’ll have the best chance of spotting it.
On a deepish, darkish UK wreck-dive it’ll do the job, and it might even be overkill on the bottom of a line on a Red Sea night-dive.
On the other hand, there can be lots of boats with strobes on their lines on Red Sea night-dives, so those 3600 lumens might usefully make your vessel stand out.

Surface Marker
Which brings us to the second part of the test. Let’s assume that you’ve made a complete horlicks of your dive-plan and ended up on the surface a long, long way from your boat cover. You simply switch on the strobe, hold it up out of the water and, hey presto, enhanced visibility.
Not so much so if it’s a bright day and the sunlight is sparkling from the surface of the sea, of course, but in typical British diving weather
I found that the strobe was sufficiently potent to attract attention at a quarter- to half-a-mile in the daytime. At night I was able to see it very clearly
at 1.5 miles, pulsing away like a good ‘un, and looking as if it would have been easily seen from much further back.
Of course, it wasn’t possible to do more than make out the flashing light at that distance, but if they’re looking for you, that’s all you need.
GRALmarine claims that the included 3000mAh battery is good for 10 hours, but in the famous bucket-test it was still going after 14 hours when I switched it off.
The flash power and pattern does alter a bit as battery power is used up, and by the end of the 14 hours it was getting a bit wheezy, but wheezy can be better than nothing.
At the back of my mind would be the comforting knowledge that if the worst ever did happen, I would have a strobe capable of attracting rescuers for at least one full night in the oggin, and maybe even two.

I liked this strobe a lot. It was exactly the sort of diving equipment I prefer. Simple, robust and up to the job it’s intended to do. It looks and feels as if it will take all the abuse a normal diving career can dish out, and still do the business if needed.

PRICE: £145
SIZE: 13 x 4cm
WEIGHT: 250g
DEPTH RATING: 150m, 300m on request

Appeared in DIVER February 2018


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