Follow the chain-of-command. For civilian engineers it goes CO - CHENG - 1st AE… For deck it’s CO - Master - Chief mate… For USN it’s CO - XO…
A USN sailor isn’t in the master’s chain-of-command. A civilian sailor is only in the CO’s chain, not the XO or other officers or chiefs.
They don’t take orders from us. We don’t take orders from them. (Except the CO.)
But if I needed something done by the USN I’d go to the XO and ask him. He usually made it happen. If the XO needed something from the deck he’d come to me and ask and I’d usually make it happen. You know, civil, polite, professional.
Every now and then someone would take umbrage at something. “He told me to do something!” I won’t address stupid people with delicate feelings.