As far as I know Combes never gave a public account of his escape from Titanic. According to known accounts a number of "firemen" left the ship in boat 3 — perhaps as many as ten. Two other firemen from Combes' watch, Podesta and Nutbean are thought to have been in 3, based on Podesta's account. I believe that's the rationale for the tentative placement of Combes (and several others on the 4-8 watch) in boat 3.
Of course boats 9, 13, and 15 are also candidates, and there were one or two unaccounted-for firemen each in boats 5, 11 and 16.