A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Brewer
Date: 2015 Oct 11, 06:39 -0700
Yes, I think they were but also on surface vessls I understand.
They are spun up with an air pump rather like a bicyle pump.
I have the operation booklet in German. Apparently they were spun up then carried up the conning tower to take a sight. All a bit hairy it sounds.
Mine was badly damaged but I got it working enough to see that it would work, accuracy similar to the bubble version.