Hello, I live near Tønsberg and can probably help you if you like.
I found 2 photoes of the Southern Venturer on the net.
Give me some time and I look into Olaf Kirkeberg. One of the whaling ships that followed the Venturer , "Southern Actor" is preserved as a museum ship in Sandefjord. There is also a" Salvesen Ex Whalers club" that might help you.
You could probably ask for help in the local newspaper http://www.tb.no/
Many of the readers are ex whalers.