There's nothing magical o mystical behind, there isn't a hidden or unconscious meaning indicating that "Boat" isn't a dream.
This Lynch's exercise (still using the freedoms that allows digital video) doesn't have a high technical quality neither the visual aesthetics that generally uses on his films but it shows a glimmer, a thought or rather to say a dream of those who many times happening to us, where we are a strange more going towards night, towards the dark side of our being where, while we sleep, we are true, we're real.
The journey to the real part of oneself.
Only a dream of Lynch.
There's nothing to fear unless we jumped out of the boat.