E-visa for cruise

I am arriving in Vietnam at the Hi Chi Minh Seaport on a cruise ship. The ship will make 3 stops in Vietnam over a 7 day period. I am spending the nights on the ship and only going ashore for day tours. I will be departing Vietnam by the same cruise ship from Ha Long Bay. Can I use an E-visa single entry since I will be entering Vietnam by ship and leaving by the same ship and not spending any nights on land in Vietnam?