From Shanties from the Seven Seas, by Stan Hugill.

A friend of mine, Mr. T. E. Elwell, a sailing-ship man and now (in 1966) caretaker of the Nautical Museum, Castletown, Isle of Man..... "Sailors,' he wrote, "sang Rye-O,' not Ree-O, for though they knew well it was called 'Ree-O,' that word was not a 'mouth-opener like Rye-O.'
Page 94, S.f.t.S.S.

So, following tradition?