Galvanic Works, a marine technology startup based in Mallorca, has published a research paper examining crew fatigue in recreational sailing. Drawing on more than 80 peer-reviewed studies across sleep science, chronobiology, and maritime safety, the paper addresses a question the sailing community has long overlooked: how cognitively impaired do sailors actually become on overnight and multi-day passages?

The findings are striking. After just 17 hours without sleep, cognitive performance drops to a level equivalent to being over the legal drink-drive limit, and the biological low point between 2am and 6am compounds this further. At sea, fragmented sleep in rough conditions recovers as little as half the cognitive capacity of a proper night’s rest on land. Crucially, sailors cannot feel it happening: self-assessment becomes unreliable after the first 24 hours.

While commercial shipping operates under strict mandatory rest regulations, recreational sailors have no equivalent framework, despite facing many of the same risks with smaller crews and less experience.

The full paper is freely available at  https://galvanicworks.com/research/ and https://www.preprints.org/manuscript/202603.1014. A free Marine Fatigue Calculator app will also be released this month on the major app stores.