Wat does this mean, many a man ought to have a bath tub larger than a boat?

just a little brief xplanation would help..thanks!Wat does this mean, many a man ought to have a bath tub larger than a boat?
In the immortal words of Lowell George (Little Feat):


';The music was hot, but my baby was not...


There's a fat man In the bathtub with the blues. Hear him moan.';Wat does this mean, many a man ought to have a bath tub larger than a boat?
They might think they know how to sail, but would be much safer in the bathtub.