An English yachtsman was trying to sail across the Tasman "under the radar'' with no documents and on a boat that was not seaworthy when it sank sometime in early January last year, a Coroner has ruled.

Coroner Brandt Shortland today (Tue) released his findings into the death of Malcolm Waddilove, finding that on the balance of probabilities Mr Waddilove drowned in the area north of Cape Reinga between January 5 and 11 last year. His body has not been found.

The 77-year-old man was a seafarer who sailed throughout the world, and early last year planned to sail from the Far North to Australia.

An inflatable dinghy was spotted drifting about 4km north of Cape Reinga early on January 5 last year with one person on board, sparking a police investigation.

Later in the day the dinghy was seen upturned and deflated.

On January 11 a yacht, known as the Boadicea, was found by a group of holidaying friends and family, submerged off Tapotupotu Bay in the Far North.

No body was found on the yacht, but two British passports belonging to Mr Waddilove were found by a diver employed by the police.

Two witnesses gave evidence to Coroner Shortland about the look of Mr Waddilove's boat prior to him setting sail.

Tim Bingham, a life raft safety service specialist, said when he saw the yacht he thought that it was not worthy to travel across the Tasman Sea and said it was in "very poor state''.

He said Mr Waddilove spoke of sailing to Australia to visit his son, "suggesting that he was potentially going to enter Australia illegally''.

Then on New Year's Eve, Marion McAulay was staying at the same marina in Whangaroa as Mr Waddilove, and said she noticed the yacht because of all the junk on board.

"She formed the opinion that this wasn't ship-shape effectively to be on the sea, and had taken photos of it.''

After the empty, sunken boat was found, a police inquiry was launched to establish whether Mr Waddilove had made it to shore.

His accounts had not been touched and no other sightings of him had been reported.

"Police were satisfied that Mr Waddilove had not come ashore at any stage.''

In his findings, Coroner Shortland noted that Mr Waddilove's yacht was "clearly not in a seaworthy condition to cross the Tasman''.

Mr Waddilove had not completed any Customs or Immigration documents and "it seems it was his intention to fly under the radar to get into Australia''.

Coroner Shortland concluded that he more than likely drowned some time between when he was last sighted on January 5 and when the yacht was found on January 11.

- APNZ