small boat with windows, houseboat
舲 centers on a small, windowed boat used as a dwelling: a houseboat or a compact vessel with cabin-like openings.
舲 combines 舟 (boat) with 令, which likely provides the sound. The character specifically denotes a small boat with windows or a houseboat.
A boat 舟 with a window-like 令 on the right: imagine a small houseboat where the 令 shape resembles a window frame, letting light into the cozy cabin.
For レイ, picture a ray of sunlight shining through the window of the houseboat: ray -> レイ, and the light fills the small boat.