Boat (ferry) transport capacity

The boat (ferry) I created in SD is getting bigger and bigger. I want to expand to be one of the biggest, if not the biggest in SD.
But even though it’s huge, it doesn’t have the capacity to carry a single tire.
I still can’t understand, to this day, why.
I went to transport a tire to another island, in order to find another tire to add another part to the boat, and the tire simply pushed my boat away from the island where it was, causing it to almost spin around.
Please developers! Make the boats capable of carrying any material. The boat can carry multiple chests, but cannot carry a single tire. Also, it doesn’t even carry a dead boar or crab.
Oh, I can’t understand this dynamic! Or rather, the lack of it.