What are those longships floating at sea?

[Hayashi.226]

I came across a couple while sailing from Undvik to Faroe. They are just floating there, something piled on the deck but I couldn't make out what. No crew to be seen.
I'm guessing they are funeral boats? But are they exactly?

 

[slothman32]

Background boats.
Just like islands and mountains.
They are out of bounds.
If you use cheat mode you can boat over there and actually go through the boats.