Well. my recent patrol in the Caribbean while navigating IXD2 got me 93k BRT. And I still, after some 40 days of cruising in the area, managed to sail back to Europe with 10knots
IXD2 is VERY nice if you know how to handle it though. First - they are available since 1942 which means the ASW is rather serious. Therefore, I never engage in the European waters - single merchants are the only exception.
There are good hunting areas neer Freetown and generally near Africa. Not that strong ASW and many targets. Additionally, IXD2 has the range - if you cannot engage a convoy at conditions that favor you, all you need to do is to wait - sooner or later you`ll find a perfect target.
Even the very single merchants can boost the tonnage easily
IXD2 are great for those madmen who enjoy extreme long-range patrols. So far, my longest patrol lasted for 156 days and included some succesfull engagements near Mogadishu and south of Ceylon
Any VII skipper been there ?
Let`s face it: VII are meant to beat the convoys in the Atlantic, IX type boats ( especially C and D, later in the war ) are not meant for this unless you know how to do it.
PS strange..... I got engaged by ASW for few times and managed to escape... rough weather and Tauschkoerper with some tactics can do wonders.