Elise Marie Eliasen

I am looking for the birth record of my great grandmother and the names of her parents. She was born in 1858, possibly April. She lived in Holmestrand as far as i can tell but I don't know whether she was born there. Her father was a sea man, possibly a ship's captain, who died at sea. Her mother remarried. Elise sailed on the Friedeberg from Hamburg to New Zealand in 1872. Her age on the ship list was given as 18 years but this does not fit with the birth date on her grave stone. We suspect she may have falsified her age to be allowed on the ship. She married in NZ in 1873, oddly her maiden name on the marriage certificate is given as Gundersen! Her husband was Robert Cullen. Her sisters emigrated to the USA. I have tried the 1865 Census with no luck and don't know where to go from here. Any help or suggestions would be appreciated.