Мой друг сел в лодку, и его куртка сразу стала мокрой.

the friend

Breakdown of Мой друг сел в лодку, и его куртка сразу стала мокрой.

• мой: my
• и: and
• сесть: to sit

Questions & Answers about Мой друг сел в лодку, и его куртка сразу стала мокрой.

Why is it сел and not сидел in Мой друг сел в лодку?

Russian distinguishes between:

• сесть → сел: to sit down, to take a seat, to get into a vehicle/boat (a change of position)
• сидеть → сидел: to be sitting (a state)

In the sentence, the important idea is that your friend got into the boat / sat down in the boat (a completed action), not that he was already sitting there.

So сел в лодку = got into the boat / sat down in the boat, while сидел в лодке would mean was sitting in the boat (describing his state after he got in).

Why is it в лодку and not в лодке?

With в, Russian uses:

• Accusative (here: лодку) for movement into something:
  • в лодку – into the boat
  • в дом – into the house
• Prepositional (here: в лодке) for location in something:
  • в лодке – in the boat
  • в доме – in the house

Since сел here means “got in / sat down into,” it describes motion into the boat, so you need в лодку (accusative), not в лодке.