Always check the weather.
Always check the directions on the paint can first for recommendations on roller type.
Many bottom paint manufacturers recommend using a 3/8" nap roller. A 3/8" nap will apply a thick coat and an orange peel-type finish because of the heavy nap of the roller. On ablative paints, that orange peel texture will smooth out some as the boat moves in the water.
A smooth, slick finish results in faster speed through the water. If you want a smoother finish, use a 3/16" to 1/4" nap roller.