Paint and gelcoat are different animals. If you roll on true gelcoat I
can only imagine that your boat will look a lot worse than it does now.
Gelcoat doesn't 'flow' like paint, rolled on gelcoat can actually serve
as a non-skid surface. Paint that is rolled on and tipped with a brush
doesn't look like paint that is sprayed on. Picture painting your car
with a roller and brush, that's what your boat would look like. Most
likely all you need is to remove the haze as S. Barthfarkle suggests,
or with any auto or boat buffing/polishing compound, preferably with a
buffing wheel, and to then re-wax it.