One word of caution: when you start boring your hole it is likely the hole boring bit will grab the material (your cabintop in this case) and jump out of control, skidding along the deck and making a mess. To avoid this start drilling, slowly, and at a slight angle to your cabintop. This way only a small portion of the bit is cutting. Slowly revolve the bit around a full revolution until you have gone all the way around. Then you can drill more vertically, although you may still find it easier to keep it at a slight angle.
who is staring at the sea is already sailing a little