One of the preparations your parents will have is to buy food and find places to store this food. Most of the food has a long expiration date. So it can be stored for a longer period of time. In every country your parents will buy fresh food like vegetables and fruit. During the trip the stock runs out but there will be bought new food in every harbor. During long distance trips your parents will even buy more food than usual. This food will be stored in every corner of the boat. After 4 years we still found food in our boat, because we forgot we stored the food there. So there is no change you will run out of food, your parents will buy more than needed.