Police are concerned for the welfare of a 49-year-old man and his young daughter who left Kawhia Harbour on a catamaran nine days ago and haven't been seen or heard from since.

Alan Langdon and his daughter Que Langdon, 6, were heading for Bay of Islands.

They left Kawhia Harbour in the Waikato on December 17 and haven't contacted their family since.

The pair are travelling by catamaran to the Bay of Islands from Kawhia Harbour in the Waikato. Photo / Supplied via police
The pair are travelling by catamaran to the Bay of Islands from Kawhia Harbour in the Waikato. Photo / Supplied via police

Police said they had grave concerns for their welfare and are seeking information from other boaties who may have seen them.

Advertisement

The white catamaran is 6 metres (21ft) in length and has blue anti-fouling paint under the waterline and a sail ID number of T878.

Police urge anyone who has seen the pair to contact police. Photo / Supplied via police
Police urge anyone who has seen the pair to contact police. Photo / Supplied via police

Police urge anyone who has seen or had contact with them since December 17 to call their local police station.​