
Technical Specifications
Overview
Tonan Maru No. 3 (Japanese: 第三図南丸, Dai-san Tonanmaru), from 1951 simply the Tonan Maru, was a Japanese whale oil factory ship. Built at Osaka in 1938 she was the largest merchant ship built in Japan to that point. She carried out whaling in the South Atlantic and in 1941 was blacklisted by the British government, believed to be because she was suspected of refuelling German vessels in the Pacific during the Second World War. Following the Japanese entry into the war Tonan Maru No. 3 was operated as an oil tanker in support of military operations. She survived 11 torpedo hits from USS Tinosa in 1943 as most failed to detonate. Tonan Maru No. 3 was sunk in Chuuk Lagoon by carrier-based aircraft in the 17 February 1944 Operation Hailstone. She was salvaged by Japan after the war, rebuilt and returned to service as the Tonan Maru in 1951. She returned to whaling and was scrapped in 1971.
Composite Risk
Multiple adverse factors, or a hard ship-specific signal, lift this hull above the fleet norm.
A coverage-weighted blend of the single component we could read for this hull; the weights renormalise over only the components present, so a thin read is never inflated and a hull is never credited a “safe 0” for a signal it has no row for. This headline is flagged low-confidence (a thin or structural-only read) and should not be treated as a verdict. Higher means riskier. Derived in-house from government-open port-State-control, flag, sanctions and our own vessel data; weight it by the coverage above.
Commercial
Price it in the Route Planner between any two commercial ports: ballast and laden legs, two fuels at live bunker prices, port and canal costs, the weather on the way, and the TCE set against the market.

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