A man has died in a fire on board a yacht moored at Albany on Western Australia's south coast, with police believing him to be the owner of the vessel.

Firefighters were called to the Princess Royal Sailing Club in Albany's harbour just after 8:30pm on Thursday to extinguish the blaze.

Police said they later found the body of a person on the vessel.

"Formal identification will take some time but it is believed the deceased is the owner of the yacht, a man in his 70s," a police spokeswoman said.

"The cause of the fire is undetermined and police will prepare for the coroner."

Earlier on Friday, police declared the yacht a crime scene pending investigations into the fire by Arson Squad detectives.

Fire crews were called to the harbour on Thursday night, with a crime scene now set up. ( ABC News: Ben Gubana )

Superintendent Dominic Wood said several lines of inquiry were being pursued.

"As a matter of course we have our arson investigations teams coming down from Perth today and they will liaise with fire investigators.

"That is the big question: how [did this fire start], so we are just waiting to find out.

"We have secured the scene here at the yacht club."

Shock among sailing community

Princess Royal Sailing Club manager Rod Hedderwick said he first noticed the fire from across the harbour.

"I live in the middle of town with a view over the harbour and I noticed a lot of flashing lights out at the sailing club area," he said.

Arson Squad detectives are expected at the sailing club to probe what caused the fire. ( ABC News: Ben Gubana )

Mr Hedderwick said the death had already been felt by the close-knit sailing community.

"It certainly is impacting on members already, we've had a number of enquiries about who it might be and whether everything is safe," he said.

"[We are] trying to get through the ordinary day's business, looking after the members who are concerned about the situation."

Mr Hedderwick said there was no extinguishing equipment on the boat pens.

"But the boats are certainly required to have fire extinguishing equipment," he said.