The other day I discovered that I was leading a dangerous life. I was unaware of our minefields in friendly harbours. Luckily, I didn't enter any of these fields. I think Seth alerted me to the existence of minefield charts on the top left hand side of the navigation station, next to the convoy route chart.
If you are not aware of the existence of this chart, take a quick look. It may keep you from the Kaleun's Vallhalla

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For your info: the latest instalment of the adventures of U-551 been posted on my website. (gripping reading, I'm told )