Only Way to Grow

Medium Used by Smart Hint

This part-found ship can only continue one way — every ship still in the fleet that could cover it agrees on where it goes.

Ship segment
Water
Cells that establish the pattern
Where the conclusion lands

How it works

Suppose every submarine is already placed, so the smallest ship still missing is 2 cells long.
This confirmed ship cell has water above it, below it, and to its left — a ship can't bend, so the only way anything still in the fleet can cover this cell is by continuing to the right.
The cell to its right is ship, whichever of the remaining ships this turns out to be.