An amateur kayaker who drowned with his workmate when they got caught in windy conditions off Port Phillip Bay had reportedly just put down a deposit on an engagement ring for his fiance.

Paul Washington, 36, and Kevin Caithness, 40, died after setting out on a fishing trip from Sandringham Yacht Club on their new motorised kayaks on Tuesday morning.

Their bodies were found yesterday morning after an overnight police water patrol and air search.

Mother-in-law to be Colleen Gusman told the Herald Sun Mr Washington, of Windsor, had his eye on a ring for her daughter.

She said the two plasterers had only had the kayaks for a couple of days and it was the first time they had used them.

Mr Caithness, of Ardeer, had a wife and two children, and had almost completed renovating his house.

His uncle told the Herald Sun: "He was very much a family man.

"He had spent the last three or four years renovating their house, and, sadly, they were not far from having it completed.

"He very much lived for his kids, and his wife, Beccy."

A member of the public found one body at the mouth of the Patterson River at Carrum just after 6am (AEDT) on Wednesday.

Police found and recovered the second body from the bay about 8.30am (AEDT).

Inspector Tim Hansen said both men were wearing life jackets when they set out in windy conditions.

"We believe it's the first time they've used these kayaks and they were inexperienced in that type of watercraft," Insp Hansen told reporters.

Police are unsure how the pair got into trouble, although the calm, heatwave conditions of the morning on the bay had turned rough during the afternoon.

"The weather was fine at the time these gentlemen are said to have left, but it gradually worsened in the time that they were out there," Water Police Sergeant Lachlan Holding said.

Insp Hansen said fishing from motorised kayaks was gaining popularity on Port Phillip Bay.

He said that with summer approaching, the tragedy was a reminder for people to check the weather before going out on the bay, ensure their vessel was appropriate for the conditions, and let others know where they were going and when they were expected back.