Some divers just don't like to dive with a snorkel strapped to their masks. A few strap it to a leg or elsewhere, but some just won't carry a snorkel. It's a decision they may not live to regret if they have to make a long swim to their boat - or the shore.
In a recent study by N.A.M. Schellart, Ph.D., a biomedical engineering professor at Amsterdam University, nine fit divers, average age 53, took two 12 minute swim tests with and without snorkels a week apart. He used various techniques to assess variables such as drag, work of breathing, heart rate, and others.
The results suggest that using a snorkel when swimming on the surface saves significant energy by eliminating the need to rotate and raise the head when inhaling. While there was no significant difference in heart rate between the two tests, the results show that surface swimming divers will tire less quickly and be more comfortable.
Furthermore, with a snorkel, swimmers can swim about five percent faster than they would without a snorkel. Clearly, a less tired and faster swimmer has a better of reaching the boat or shore. And recognizing that some divers die of stress-induced heart attacks on the surface, there's even greater reason to use a snorkel.
His recommendation: "make the snorkel a mandatory piece of equipment of the scuba diver."
"Swim Performance With and Without Snorkel and the Underlying Energetic Differences," N.A.M. Schellart Undersea and Hyperbaric Medical Journal, Volume 48, Number 4, Fall, 2021.