It will depend on what kind of boat is in the dream as to its interpretation.
A ferry or piloted boat holds all the symbolism of the journey across the river styx after death.
Today it signifies the giving up of selfish desires. Having been able to do this, we may be ‘reborn’ into a better life, or way of living.
A small rowing boat would suggest an expedition of emotional discovery but one often undertaken alone.
A yacht might suggest a similar journey done with style, whereas a large ship would suggest creating new horizons but in the company of others. Early seafarers referred to their ships as ‘she’ largely, it is thought, because of the close dependence they had on them for life and because they were difficult to manage.
Today ships have lost that personal association. What a boat does in the dream will have relevance as a reflection of our waking life, e.G. Running aground, pulling into harbour etc.
To dream of disembarking indicates the end of a project, successful or otherwise.
If we dream of missing a boat it shows we have not paid enough attention to detail to a project in our waking lives.
Also consult the individual entry for boat / ship.