River & Sea Transport - supply distribution

[Templer]

Manual page 59:

Rail, River & Sea Transport
Each turn, the steamboats and trains left unused during the movement phase (see chapter) will be available for supply distribution. These will be used to transport.

For this, do the steamboats have to be on the rivers, or may they remain inside the ports?

[moni kerr]

Supply movement uses your river pool which is abstract, so don't worry about keeping ships in port.

[Pocus]

indeed, the unused points will allow supply to flow more smoothly and farther.