It is probably a result of the translation of a phrase that was wrong to begin with. In fact, you're not far off with your comparison.
In the German speech they say "Wahnsinnige fahrt voraus" which means "crazy/senseless/mad speed ahead", actually it pretty much does mean "ludicrous speed ahead!"
The German navy did not use that as far as I know. Rather the command would be "Aüßerste fahrt" or " N x Aüßerste fahrt"
|