Three men were forced to swim to shore off the island state's remote west at the weekend when their five-metre dinghy capsized.

A few days earlier, a 65-year-old man died on a boating trip with his son in the southeast. His son, 33, was rescued at night after spending about eight hours in cold seas.

Three friends died on a mid-October day trip after getting into trouble off the northwest coast. Widespread searches were unable to recover one man or the vessel.

"All boat owners are urged to ensure their vessel is seaworthy and safety equipment is in good condition," Sergeant Kriss Lawler said.

"Police want to see people enjoy their time on the water and to make it home safely."

Sgt Lawler, of the Tasmania Police Marine and Rescue Services, said life jackets must be worn by everyone aboard boats less than six metres long. Flares and emergency beacons should be stored in an easily accessible place.

"It's vitally important that anyone heading onto the water in a boat is aware of their limitations, and that they carry all of the equipment required to keep them safe," he added.

Police also advise people to plan their trip, never mix alcohol and boating, and be aware of forecast weather.

Rough conditions hampered searches for the three locals in the northwest.

Australian Associated Press