There were quite a few of then in Vietnam in the 1960/early 1970’s. (Wooden tugs. Operated by Alaska Barge if I remember right)
They were flying Panama flag, with quite some characters working on them.
Those operating on the Mekong had piano wires stretched from the masthead to the rails as protection against rockets I was told.
One of them got hit by a rocket below the deck line in the aft peak area- It did not explode and could not be removed.
The British Master,(who had been my Father-in-Law’s Ch.Off on a RAF landing ship), decided to proceed to Singapore to seek assistance. Not very popular to arrive with an unexploded ordnance stuck in your hull.