vast, expansive
漭 centers on vastness and expansiveness, especially of water, like a boundless sea or flood.
漭 combines the water radical 氵 with 莽, which likely contributes the sound and the idea of thick or overgrown, together suggesting vast, spreading water.
The water radical 氵 beside 莽, which looks like a dense thicket, suggests water spreading endlessly through a vast landscape.
For ボウ, imagine a vast ocean stretching to the horizon, and you throw a bow (ボウ) into the water, watching it float away on the boundless sea.