The sub was putting off the British harbor pilot. The topside crew was still involved in that when the sub cleared the breakwater and exposed the topside crew to the full force of the sea conditions beyond the breakwater that included 50 MPH winds and 20 foot swells.
Result: Four crewmembers washed overboard and two of them drowned or battered to death against the sub's hull.
The CO and the XO should have either ensured that the pilot transfer was completed in a timely manner before the sub cleared the breakwater or, if that was not possible, aborted the pilot transfer, ordered the topside crew and the pilot below and taken the pilot along for a patrol.
British authorities expressed shock that the pilot transfer had not been completed well before the sub cleared the breakwater.
This is because the British expect seamanship and forehandedness among it officers and NCOs. With our nanny-state navy, admin, training attendance, and petty rule following are the key indicators of promotability. That we don't get competent leadership is because it is not important on our scale of things.
And make no mistake about it. Attempting to conduct topside operations in 20ft swells is not competent seamanship. The weather conditions were no secret, and topside should have been cleared within 50 yards of the pier. There was no excuse in leaving sheltered waters before full rig for dive had been in place. You don't do what these guys did. An accident was not a likely outcome - it was going to happen, and with these guys in charge the death sentence was passed with the posting of the watchbill.
My prayers for the sailors, dead and injured who did their duty as ordered. I have no sympathy for my fellow officers in command on that day.
"The topside crew was still involved in that when the sub cleared the breakwater and exposed the topside crew to the full force of the sea conditions beyond the breakwater"
If this is true, it betrays a severe lapse in judgement.