All of the following may already be on this forum, however if it is, I couldn't find it, so if it is I apologize for posting it again. I don't know how to make a link to a PDF but If you do a search for "Hydrodyne drone minesweeper in the Long Tau River" and click on the following PDF in the search results. "PDF Related to Monthly Summaries, 1967 July - Naval History" you will find a photo of a Hydrodyne minesweeper along with a few word about the boats at about 100 pages into the the document. (Near the bottom of the document) Also if you click on the following link, I may be wrong but I believe many of the photos of minesweepers are Hydrodynes. The Hydrodyne minesweepers were 23 feet long. https://brownwater-navy.com/vietnam/BoatsMisc.htm And following is a link to a YouTube video that I also think has Hydrodyne minesweepers in it.