Well that can work. Necessary as radar is, especially in later half of the war with the convoys, it is sometimes more fun to not have it. Can still do pretty well in early period of war without it. Also, perhaps consider it training for having the real life discretion of US submarines, because in forthcoming version of TMO, some land based radar units and observation posts/naval bases will have radar detection as well as aircraft and a few later in war.
I do wish I could have had the work around etc ready for this release but at time of release it was not a sure thing. I have it ironed out now, not a fix, but a work around so player avoid the issues you suffered.