At the 'Explosion' museum at Priddy's Hard they have an early 20th century 'river' mine of possibly Rumanian origin.

Not knowing what your mine looks like I can only describe the one from Priddy's Hard and hope that it is similar.

The mine consists of two drums.  The bottom drum is the larger and has a row of holes (12?) around the top on the sides.  Just above these is a row of spikes (possibly 6). Halfway down the drum is what appears to be a copper band to hold it together.  I believe that this is the 'business' part of the system.

The upper drum is connected to the bottom one by a metal 'stalk' and is half the width of the bottom one.  It is a plain drum with no holes or spikes.  I suspect that this is the buoyancy float the weapon system.

Apologise that I cannot give any scale or actual dimensions, but from  memory it was much smaller than a normal naval mine.