Ok thanks, I found a different solution and am now using the MaGUI mod, which has both RAOBF wheel and a chronometer. Some little adjustments in the menu.txt were necessary but it works like a charm now. And the JFO mod CTD appearently came from faulty installation instructions in ther German readme, no problems when using the English instructions, don't know why though.
I do have two other questions, though:
Is there some optional mod for NYGM that adds a little more radio traffic? I'm feeling a little lonely out there
and:
I've read in the NYGM manual that all convoys -even early war convoys- have at least 3 escorts. Why is that? And is it even true for convoys in the Atlantic that are out of escort range? I haven't encountered any convoys so far so I can't tell.