Four-year-old Euan Gordon had only been able to wave to his dad Alasdair when the vessel docked just 100m (328ft) from their home in Oban.
But now Alasdair has finished his stint at sea and returned to his family.
Mum Seonaid Russell said it had been like Christmas Day when her son was reunited with his father.
She said Euan had woken up at 05:00 with “excitement” and anticipation.
Alasdair Gordon, 41, is in charge of the deck on the Pharos, which is responsible for the operation of Scottish lighthouses.
Under normal circumstances, when the boat is moored near his home he can spend the night with his family.
But since the lockdown began, Alasdair and his crew have been instructed to stay on the ship when it is tied up in dock.
However, he has now finished his latest stint at sea and been allowed to go home for 28 days.
Seonaid, 34, said Euan had been counting down the days and knew his dad would be allowed off the ship on Thursday.
She said: “Euan was very excited and woke up particularly early because he he was so looking forward to seeing his dad. It was like Christmas for him.
“It was so lovely to see the smile on Euan’s face.”
The family live in a cabin in the grounds of Seonaid’s mother’s house.
“Euan loves baking and his granny had promised she would bake a cake with him in the morning for his dad,” Seonaid said.
“So he ran through the garden to his granny’s house at 06:00 and baked a beautiful cake for Alasdair’s welcome home.”