I restarted my career after putting RSRD in place, and went back to Yakishima (?), which is the first port you meet on the way to Tokyo. I did quite well ( though not always at first try) as I sunk two minehunters, a destroyer and a heavy battle cruiser - oh, and a little sub chaser. Might sound impressive except that the destroyer and battleship were moored and as easy as sitting ducks. I still didn't get any reaction after sinking these two - possibly because I had seen off the three active ships patrolling the area first - but I think I found a 'bug', which made it easier for me to get away with it all. Up to the north of the bay there is a long spit of coast, with plenty of traffic behind it - I found three warships patrolling there, and figured they might come looking for me, but I was in no danger because they could not seem to work out that they had to go ROUND the spit. What they did was travel up to the spit, stop, and then travel back the way they had come, in reverse! It looked quite odd watching a ship with a bow-wave going backwards, but that is what they did and continued to do, backwards and forwards. Great fun, and now having got back to the open sea, I see a merchant heading my way - so I am on a roll!!
