how much renown before I go up in the world?

[She-Wolf]

I have finally got my act together - only taken me about a year realtime (though some of that I have been playing my other two most-liked games the X-series space game from Egosoft, and Oblivion). I have now completed 2 ( two!) patrols without coming home with tail between legs because I drowned a friendly or a neutral. Instead I have notched up three kills on the first patrol, and four on the second, should have been five but the beast wouldn't sink. True, they were not very big, but that means they are harder to hit. I survived being hunted by a pack, and being searchlighted and very(?) lighted at night, so I came home unscathed, with empty tubes,a whole crew and looking forward to renown, albeit of modest proportions. Well, I think I have got somewhere around 900 all told now, which I know doesn't amount to much compared to you clever folk, but it is the first rung.. however I am puzzled. I dished out some medals to my crew and then had a look at the submarines page and saw that there was a whizzier model than the IIA I have had the um, pleasure of careening around in for the last several months. This other model (IID?) had a figure of 500 renown next to it and I thought that meant I needed that much to captain it, so I clicked on it - but I find myself back in the old tub again, bless its rusty little heart. Can you tell me how a girl progresses to the next type - or is it dependent on the year and where you are based??