One of SH3's big drawbacks is that the way that escorts detect your boat isn't as accurate to historical standards and there isn't much that the modders can do without a dev released tool. So its not very easy to do what Kretchmer did, zipping in and out of convoys though getting close can be done, however it does require about as much attention to your position as the real kaleuns needed. Just keep plodding on. The benefits of being an armchair Kaleun is that there's always next time.
