Start with a square piece of paper.
Fold it in half.
Fold again, but by the other corners.
Unfold. You should have an X.
Flip the paper over.
Fold in half again, but in the other direction. This time, do NOT unfold.
You should have a V, with the bottom point facing you.
Squish into a diamond.
End up with this. MAKE SURE THAT YOU HAVE TWO FLAPS ON EACH SIDE OF THE DIAMOND.
Fold in a side.
And the other.
Squish it back into a diamond.
End up with this.
Fold down a sail.
Unfold, but not all the way. Crease.
Tuck the smaller sail into the hull to hide that ugly crease.
Flip the boat over. Fold the bottom of the hull to the top of it.
Unfold, but not all the way.
YOU ARE DONE! Decorate desks, make oceans of sailboats, give them to friends... or not. The choice is yours now that you are an origami sailboat master! And don't forget to have FUN!