Bottomry break-even

Claim (verbatim)

Bottomry break-even. Joins actuarial insurance pricing to maritime archaeology. A fourth-century BCE Athenian bottomry loan was repaid only if the ship survived the voyage, so the premium over ordinary land-secured interest is a pure risk price: if lenders broke even, the spread directly encodes the probability that a voyage ended on the seabed. The seabed keeps the other ledger — the dated shipwrecks archaeologists have counted and catalogued. These are two completely independent instruments reading the same underlying hazard, one through the money market of the Demosthenic speeches, one through survey archaeology, and if both are read correctly they must agree. The conjecture predicts that the per-voyage total-loss probability implied by attested loan spreads on the long Pontus and Sicily routes — on the order of one voyage in ten — matches the loss rate reconstructed from wreck counts and grain-fleet voyage volumes to within a factor of two, never falling outside that band.

Prediction clause (verbatim)

Attested bottomry premia (12.5-30% per voyage in the Demosthenic corpus) over the land-secured lending benchmark imply a per-voyage total-loss probability of 8-20% on the long routes (Pontus, Sicily); an independent estimate from dated Aegean-route shipwreck counts, survival-corrected and divided by voyage-volume proxies (Athenian grain-import needs of roughly 500-1,000 shiploads per year), will land within a factor of 2 of the loan-implied band, i.e. between 4% and 40%, never outside.

Kill-dataset (verbatim)

Kill: the Strauss/Parker Mediterranean shipwreck database crossed with attested Demosthenic loan terms and standard grain-fleet estimates. Independent loss-rate estimates differing by more than x4 kill it.

Novelty / leakage triage

already answered in the literature

The actuarial reading of bottomry is the established historiographical interpretation — de Ste. Croix's 'marine insurance in the costume of credit', with rates seasonally and route-indexed — which is the conjecture's core. The cross-check against wreck-derived loss rates was not located, and a commonly repeated informal ~3% per-voyage loss figure sits below the conjecture's implied band — a tension any resolution must engage.

• de Ste. Croix's bottomry-as-insurance reading (summarized in 'The Law of Averages') — The established actuarial interpretation

Predictions

No prediction registered yet.