Semper Fi to your son, and a big "Welcome home" to you! My father served on PBRs during 68-69 timeframe.
If your father has not, he should look into the Gamewardens of Vietnam. I think there are more PBR's sailors there than in any other veteran's organization. I have gone to a couple of their reunions and they are great people. I served on a support LST for deployments to Seafloat and Solid Anchor in 1970 and 1971.
By the way, I forgot to say thank you very much.