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May 2018    Download the Entire Issue (PDF) Available to the Public Vol. 44, No. 5   RSS Feed for Undercurrent Issues
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Things Are Not Always As They Seem

especially to an ill-informed passing boater

from the May, 2018 issue of Undercurrent   Subscribe Now

The latest furor to hit scuba social media occurred after a Florida boater posted a YouTube video, showing him picking up a lone diver waiting at the surface with his surface marker safety sausage fully inflated. The furor came about because the boater wove a great tale on how he had "rescued" this "lost' diver" off Fort Lauderdale and returned him to his dive boat.

While the diver might have been grateful for the lift, he may have been equally happy to wait until he was picked up by his own boat, which at the moment was picking up their other divers in the water.

The dive boat Aquaview, operated by South Florida Diving Headquarters, can carry 35 divers. That's a lot of divers to have in the water, and most likely they were scattered about, so it takes time to pick them all up.

It seems that the "rescued" diver had a 10-minute deco-stop to do before he could surface, so divers in his group surfaced ahead of him and he became separated. Social media questions arose: Why was the diver on his own? Where was his buddy? Why had his group not waited for him at the surface?

The east coast of Florida usually sports a strong current that often travels in a different direction and a different speed compared to currents deeper, in which case, those at the surface would end up be drifting nowhere near another diver at depth.

So, why had this diver incurred a decompression stop when the others in the group had not? And why had he no buddy?

Different Computers Give Different Information

This brings us to his computer. It was a Suunto, which uses a Wienke RGBM algorithm, in common with a lot of other European-made computers. Could it be that the other divers in the group were using popular America-made computers that feature the older DSAT algorithm? Probably.

The DSAT algorithm for the no-stop section of a dive gives maximum bottom times similar to the PADI Recreational Dive Planner. Both allow the user a lot more no-deco-stop time with an unhindered ascent to the surface.

People diving together should use a computer with the same algorithm.

However, the RGBM algorithm mandates much more deco-stop-time if the diver makes a second dive after a short surface interval. It is safer, as nitrogen absorption by the tissues goes. But, is it safer if you are left alone at your safety stop waiting for the computer to clear, while your group surfaces and gets back on the dive boat?

The "rescued" diver had a large delayed surface marker buoy which he had sent up to mark his position while he waited out his computer. The captain of the Aquaview dive boat would have been well aware of this while he went off to pick up other surfacing divers. In fact, this is a common practice.

Many of us divers have been in a similar position zxand hitched a lift on another boat when offered. Why wait when you can ride? Yet, the boater went to great pains to tell the world he had "rescued a lost diver."

Of course, the crew of Aquaview believed that nothing untoward had happened when the boater dropped the "lost diver" into the water close enough for him to swim over to them.

Indeed, the website of the South Florida Diving Headquarters even asks, "Does the thought of lazily drifting along the reef with the current and surfacing when you are ready appeal to you?"

Well, it appears that the diver subject of this tale was doing exactly that.

After all the social media attention, the boater who shot the video obviously had second thoughts about his "rescue" and removed it from YouTube, but still, it leaves the question as to why the diver was alone?

Assuming he was not a certified solo or self-reliant diver, could it be that his assigned dive buddy was using a different computer?

Now that would be a mistake. You see, people diving together should use a computer with the same algorithm. Otherwise, it is inevitable that each will need to manage the dive differently.

I've witnessed divers at Truk Lagoon enjoying the square profile of a wreck dive, armed with both a Suunto and an Oceanic computer, who became confused that they provided different deco requirements. Many were unaware that the Oceanic computers manufactured during the last several years feature a dual algorithm, either of which the user can select. Oceanic's DSAT algorithm is very different from Suunto's RGBM, but the Pelagic+ algorithm on an Oceanic computer (and clones thereof) is similar. It's important to set the appropriate one before diving.

One last point. The "rescued" diver had a visible safety surface marker buoy. Often, dive companies ask everyone to stay in sight of the dive guide. Sometimes buddies are assigned. If he had been with a buddy at the surface, he might not have been safer, but he would have had someone to chat with while he was waiting to be picked up.

-- John Bantin

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