"They were heading out to the middle of the bay - the Gulf - that's another thing that became kind of standard practice, we didn't hurry the destroyers around the beach any more, when it got dark, we'd take 'em out thirty or forty miles out in the middle of the Tonkin Gulf"

This quote is referring to the Vietnam War. During the war, the US Navy would send out destroyers out to the middle of the Tonkin Gulf to secure the coastline. This became a basic practice as it was much safer for the destroyers to be out in the middle of the bay rather than near the beach. This was done when it got dark, as the darkness supplied cover for the destroyers. This quote is highlighting the value of the US Navy's strategy of keeping the destroyers out in the middle of the bay, as it was a more secure choice than being close to the beach. This technique was used to protect the coastline and the destroyers from any potential attacks.