type II disks on the hull
 

Good day everyone!

Please help me to understand what are these strange disks on both sides of the hull are for and, subsequently, what color were they?

I am building a type II model and wondering whether i should paint these circles in different color.

Thanks!

I think those are hydrophone sound heads. I haven't found any images like yours yet but there is a museum ship in Finland.
Submarine Vesikko.