Ship choices: from Cruise ship to Tanker

Using multiple resources at wiki answers and how stuff works I have realized that most cruise ships do not travel at a very high speed, usually in or a round 19 knots (just under 40kmph). Also I have realized that cruise ships run at a seemingly high cost, but if costs are compared with commercial cruising (i.e. added price because it's a business) it would be cheaper to spend your ENTIRE retirement on cruise ships than it would to live in most retirement homes. With certain adjustments a cruise ship is our ideal boat. So my question was there…I wanted a cruise ship but that was faster, had less luxury, and was more prepared for storms. I did some research on the largest cruise ships I could find, and came up with "The Freedom Of the Seas" the ship with the biggest gross tonnage. It lays 338.77m long stands 63.7m high (15 decks) and six motors each with 17, 000 hp! Unfortunately this ship comes for a high cost and at $800,000,000 (US) might be running a tad bit over budget. However considering that, think about how the cheapest room I could find on this boat was $659 (CAD) holding 2,147 more people than the titanic!!! I'm sure these costs even out. So to take the basic structure of a cruise ship and to put it with a different body would take up to much room and cost far to much. So I finally dawned on the conclusion of a tanker, with the amazing cost of only one (US) cent per gallon! I started to research this new idea, and realised the gigantic sizes of these monsters! Finally finding the "Knock Nevis" one of the largest which is taller than THE EMPIRE STATE BUILDING. In 2005, 2.42 billion metric tons of oil were shipped by tanker.[44] 76.7% of this was crude oil, and the rest consisted of refined petroleum products.[44] This amounted to 34.1% of all seaborne trade for the year.[44] Combining the amount carried with the distance it was carried, oil tankers moved 11,705 billion metric-ton-miles of oil in 2005 (wikipedia info in grey) The knock nevis can hold 564,650 DWT of cargo and is 458.45 m long, It has also been out of service since 2004 is the perfect ship to modified to our new ship since it has been lying around for the last 50 years.