The Clam is a multifunction self-rescue dinghy, designed for use as a proactive lifeboat (as well as a yacht tender) that allows the sailor to sail to safety.

"[5] Callahan departed from Newport, Rhode Island, United States, in 1981 on the Napoleon Solo, a 6.5-metre (21 ft) sloop he designed and built himself, single-handedly sailed the boat to Bermuda, and continued the voyage to England with friend Chris Latchem.

In a growing gale, seven days out, his vessel was badly holed by an unknown object during a night storm, and became swamped, although it did not sink outright due to watertight compartments Callahan had designed into the boat.

Unable to stay aboard Napoleon Solo as it filled with water and was overwhelmed by breaking seas, Callahan escaped into a six-man Avon inflatable life raft, measuring about six feet (1.8 m) across.

He stood off in the raft, but managed to get back aboard several times to dive below and retrieve a piece of cushion, a sleeping bag, and an emergency kit containing, among other things, some food, navigation charts, a short spear gun, flares, torch, 3 solar stills for producing drinking water and a copy of Sea Survival, a survival manual written by Dougal Robertson, a fellow ocean survivor.

He routinely exercised, navigated, prioritized problems, made repairs, fished, improved systems, and built food and water stocks for emergencies.

Having lost a third of his weight and being covered with scores of saltwater sores, he was taken to a local hospital and spent six weeks recovering.

During his journey, Callahan experienced a few positive elements aside from suffering, describing the night sky at one point as "A view of heaven from a seat in hell."