The word "cubited" is spelled with a "u" after the "b" to indicate that the vowel sound is short. The IPA phonetic transcription for this word is /ˈkjuː.bɪ.tɪd/. The first syllable "cub" is pronounced with a long "u" sound /kjuːb/. The second syllable "it" is pronounced with a short "i" sound /ɪt/. The final syllable "ed" indicates the past tense form /tɪd/. Therefore, "cubited" means to measure or calculate by cubic units.
Having the measure of a cubit.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.