Vegetius said that sailing was safe from May 27 to September 14 but that the two doubtful, or dangerous, periods ran from September 15 to November 11 and from March 11 to May 26.
Vegetius Renatuse sõnul oli laevasõit turvaline 27. maist 14. septembrini; kaks mitte eriti sobivat ehk ohtlikku perioodi olid 15. september kuni 11. november ning 11. märts kuni 26. mai.