Ok, you have your yacht, you have sails and rigging, steering, navigational equipment, and plenty of fresh water; what more could you possibly need to make it across an ocean? Time
Time is by far the most important item to have in order to make the crossing possible. Many sailors have all the required items to make the journey, but lack the time and therefore can never leave their mooring.
Sailing is slow and the ocean is big, having time lets you wait for the right weather, and lets you relax as you slowly make your way through the waves. If you have a short schedule and just enough time to make it from Point A to Point B, then you won't have enough time to make the crossing. Something will happen that will exhaust your limited allotment of time and you will run out of it while at sea. Too much wind will force you to change course or slow down, too little wind will force you to a slow crawl. The 100 mile per day goal is just an illusive figure that is never achieved. Not once in our passage did we ever do 100 nautical miles in a day. Some days we did less, others we did more, but we never managed to get 100 on the nose. Yes, our average at the end of a long voyage was around 100 per day, but what if you don't have that many days available to you and you only get to experience the 80 mile days?
Time away from work, away from friends and family, time away from your life. These are all components of our world that cost time and if you can't remove yourself from these expenses, you will never be able to afford to cross an ocean.
On the other hand, if you simply take the time to do it and allow no time to be squandered on shore, you will then spend all of your time crossing the ocean and getting to the other side. Your expenses will shift and you will find that crossing and ocean is easy, all you need to do is find the time to do so.