While I was in the Navy, I spent a year in Danang Viet Nam. I was stationed on a floating dry dock, AFDL23. We were adjacent to Tien Sha ramp where the LST's landed bringing in supplies. They brought this dry doc over from the Philippines. It was essentially shore duty. What they did was build a large steel sea wall at the shore line to keep it from filling up. Then the Hawaiian dredge dredged out a big hole for the dock to submerge into. Anyway we serviced all the small craft in the area. We could actually take in a destroyer escort if needed.
Your mention of the "floating dry dock" reminded me of a memory from my time in Vietnam. There was a small Navy facility somewhere near I was (at Camp Eagle, west of Phu Bai and about 40k from Danang) that repaired river patrol boats. It was designated as a U.S.S. something (I don't recall the name) but had no means of its own propulsion. The Navy had failed to arrange for mail to be brought to this unit, so the medevac pilots in my unit had set up an arrangement (sometime before I was there in 1971) to pick up their mail in Danang and deliver it to the "ship". In return, any members of my unit (the 326th Medical Battalion, 101st Airborne Div (Airmobile)) who made it to the ship were welcome to stay for a meal. I had the good fortune to fly out to this "ship" several times and got to enjoy a really good meal prepared by Navy mess personnel. Good memory.