Its definitely havois. When theres a nekuda next to the vov with a dagesh in, then its pronounced as a vov. It has a dagesh in the vov because its after a hey with a patach under it.
Blueprints – if a vov with a dagesh is always voo then how do you read what we read as Shivisi which has a dagesh in the vov? Or yivoshu? Etc etc