Answer:
My Russian dictionary has a diaresis over the e - Потёмкин - and being of the Soviet era, gives the translation as "the dark one", which presumably means Satan. The diaresis converts the e (ye) to yo, which is always stressed in Russian. The o in the preceding syllable, being unstressed, degrades to a as in father. The complete word is thus
Pa(h)-TYOM-kin
Note that the y is sort of absorbed into the t - a process called palatisation, which therefore makes a sound closer to the English ch. We might write it as
PaCHOMkin
Note that these remarks are based solely on the uncapitalised word in the dictionary. As a name, it might be something different. But I think calling a (pre-revolution) battleship Satan is more than probable.