Definition of well-boat:
(adv) :
(manner) Accurately, competently, satisfactorily.
(adv) :
(manner) Completely, fully.
(adv) :
(degree) To a significant degree.
(adv) :
(degree, UK, Ireland, Commonwealth, slang) Very (as a general-purpose intensifier).
(adv) :
In a desirable manner; so as one could wish; satisfactorily; favourably; advantageously.
(adj) :
In good health.