If you set out across an ocean then you need to plan how much food and water are required as obviously there are no shops in the vast blue yonder and the only additional source of food that can be obtained from the sea is fish. As a rule of thumb for the food you multiply the number of days that you anticipate for your crossing by the number of crew and multiply the result by three to calculate the number of meals. You would be well advised to add another 50% in case you take longer than estimated.
      For water consumption you should plan two liters per person per day. Liquid consumption does not have to be water and can be replaced by fruit juices or other soft drinks. Dehydration is always a risk especially in the tropics and ii is important that each crew member drinks a large bottle of water per day and by having separate bottles for each person allows everybody to gauge their own consumption. Another easy way to see if you are correctly hydrated is to check the color of your urine. If it is any darker than a light straw color then you need to increase you liquid intake. You may be able to collect rain water from water running off the sails or Bimini top however be aware that in the tropics a lot of the time that it rains in the ocean it is either at night during squalls or during periods of bad weather where you may be occupied steering or reefing sails. Many cruising yachts have large fresh water tanks and these tanks need to be kept clean and alga free. Drinking poor quality water during an ocean passage is a recipe for disaster. Although we had 800 liters of water tankage we did not use this for drinking water as our tanks are made from aluminum and I believe this could create a health problem if we consumed this water over many months. The water in the tanks was used for showering, washing clothes and plates. We took bottled water and collapsible plastic jugs filled from the port in Gran Canary for crossing the Atlantic but we needed another plan for the Pacific as there were no ports on our 5000 mile onward passage. I had taken the precaution to have a water maker installed on the boat before leaving which could produce 30 liters per hour and this was run off the electrical system. If you count on using a water maker in the Pacific it would be wise to learn how to service and maintain your system and take spare filters as you will not find repair facilities until you reach Tahiti. If you are going to drink the desalinated water from the water maker then you need to ensure that you absorb sufficient vitamins from other sources such as food or tablets as the water is demineralized.
      Having calculated the quantity of food required you then have to decide what food you are going to take with you and the storage requirements both in terms of space and conservation. You need to decide on how much fresh food you are going to carry and calculate how long it is edible. Additional caution is required whilst at sea so that the crew remains healthy and fit. A past sell buy date on your favorite yogurt or a refrigerator that has not kept its contents at below 5° Celsius can incapacitate the crew. Whilst on land we are used to buying fresh food every few days however the reality of an ocean passage of several weeks means that you only have fresh food for three to five days and the for the rest of the passage you only have preserved food. Freshly caught fish and freshly baked bread have a very special significance in the middle of the ocean when you have been eating tinned food for ten days.  Due to the limited use of a refrigerator for ocean passages due to their high energy consumption we met several cruising boats who did not have such equipment on-board. Using a deep freezer to conserve food for months is an option but it is costly in terms of energy and must be run twenty four hours a day even when you are anchored in a bay. It adds an additional complication if you have to leave the boat for any period of time as the energy consumption is twice that of a refrigerator. Many of the boats that we met that have a freezer also had to install a genset. This is a diesel motor whose only function is to generate electricity and can be run automatically when the level of the batteries drops below a certain voltage.
     I decided not to install a freezer and we relied on preserved foods when the fresh food was finished. The range of preserved food available in Europe is wide from canned fruit and vegetables to fish and meat. We tested before leaving on our voyage both dehydrated pasta mixtures and tinned meats and found that we did not enjoy eating any of these products. North America has a large domestic canning history and they preserve meat, fruit and vegetables while in Europe home based preserving is centered on fruit and vegetables. There are several reasons for this in Europe as many types of meat are preserved in the form of pates or cured to produce ham or salami. Meat is rarely tinned in Europe without being in a sauce such as bolognaise. If the food you are trying to conserve has a sufficiently high acidity content such as fruit and many vegetables then you only have to heat the product to just above boiling point and then bottle it and it will keep for months. If you want to preserve chunks of chicken, pork, beef and lamb then you need to use another technique which is reserved for the professional food industry in Europe but is available to individuals in North America. You need to use a pressure canner that heats the food to at least 116°C which is required to kill any botulism bacteria. This bacterium is much more common in the U.S. and possibly explains the widespread use of the pressure canners. In Europe I could not find a domestic pressure cooker that reached the required temperature and autoclaves are restricted to professional users and are very costly. I presume that there is a degree of protectionism by the European food industry which does not allow the general public to purchase meat preserving canning equipment. There have also been some well documented accidents in the U.S. where aluminum pressure canners have exploded.
     The reason that we prepared 90 one liter mason jars of food was not for the Atlantic crossing where food is both plentiful and adapted in the Canary Islands for ocean sailors but to cope with a Pacific voyage where supplies are often rare and sometimes restricted to very basic supplies. In the Canary Islands the large supermarkets will vacuum pack and freeze different types of meat which will keep in the fridge for up to five days which can be a big help on the typical 15-20 day crossing. They also have dried hams and semi-cooked bread that only needs heating in the oven and which will keep for several weeks. They also have a large selection of fresh fruit and vegetables, fruit juices and canned products. Compare this to provisioning in Santa Cruz in the Galapagos where we had 3000 miles of ocean to cross before reaching the Marquises and only had access to flour, a few loaves of bread, some grapefruit and you will realize why we were interested to take with us three months of bottled food. Provisions were even more basic in the smaller islands of the Marquises and we had difficulty in obtaining local currency to purchase the few items that were for sale. On some of these islands there are no shops or restaurants, the local inhabitants produce or catch their food and have no great need for food shops. The situation is a little better for visiting yachtsmen on the main atoll of the Tuamotu Atolls, Rangiroa where they had a couple of supermarkets and several restaurants but are situated nearly 5000 miles from Panama.
     The pressure canner, which was purchased in the U.S. via mail order, was put to work in the middle of August 2010 two weeks prior to our departure. Mireille and group of her friends spent the weekend preparing ninety jars of food which included chicken, lamb, beef and pork chunks without any sauce. They also prepared some complete meals such as Boeuf Bourguignon, Navarin D’agneau and Bolognaise sauce. They partially cooked the food and then placed it in sterilized sealed mason jars which were then cooked for 90 minutes in the pressure canner. The air escaping via the rubber seal when the jar cools creates a vacuum in the jar which seals it. We only lost two jars due to faulty seals during the entire trip and the pleasure of eating a Boeuf Bourguignon while crossing an Ocean in a sailing yacht is exceptional. Another aspect to consider when cooking at sea is that one pot meals are far easier to prepare than three pan meals especially in rough weather and if the food is already chopped into bite size pieces it is easier to eat with one hand while you hold your bowl in the other hand.A normal Pacific swell is 2 to 3 meters high and we would have to either hold the closed pan on the galley stove or attach it with wire to stop it falling off the stove when the boat rolled heavily. Our galley stove only has two burners with an oven and only simple meals were made on our ocean passages while more adventurous culinary meals were left until we arrived in a sheltered bay.

    When we had run out of fresh salad items we would replace them with tinned sweet corn and tinned lentils that would be put in the fridge in the morning so that they were cool for the midday meal. We did the same with tinned fruit as it tastes better when it’s chilled. 
    In bad weather we would adopt an ”eat what you can” attitude where we would wrap a piece of cheese in a tortilla. There was never a queue to be the galley slave in poor conditions and the crews’ appetite was often diminished. During one three day storm in the Atlantic my brother-in-law only managed to eat two apples and we all benefited from reduced waistlines when we arrived in the Caribbean.
     We were lucky to catch a significant number of fish both in the Atlantic and the Pacific which improved our bottled food diet. We would have sashimi (raw fish) in lemon and olive oil. When we cooked the fish in a pan we would not use any oil or fat but put a fine sprinkling of salt in the pan to stop the fish steak from sticking and sometimes we would curry the fish especially if it had been in the fridge for two days. Bread making only started in the Pacific after we had run out of bread several days before. Magali attempted to make bread however the result was not edible. Necessity being the mother of invention we tried again and realized that the initial failure was due to adding hot water to the flour and yeast mixture which killed the yeast and hence the bread did not rise. Using cabin temperature water 26-30°C the bread rose correctly and from then on we had our daily bread or at least until the gas ran out in the Marquises Islands.
     To cook the food on-board and to prepare hot drinks we needed gas which was supplied via camping gas propane bottles. We carried four bottles of 3kgs each that can be exchanged or refilled and each bottle lasted about three weeks. We had full gas tanks which were refilled in Panama and expected to be able to refill them on reaching French Polynesia however neither the Marquises Islands or the Tuamotu Atolls used this type of gas bottle and we had to hire a local boat to take as to a village in Fatu Hiva where they sold 12kg bottles that also required a different regulator. The large gas bottle would not fit in the gas locker and had to be disconnected and lashed to the rear pushpit (balcony) while we were sailing which was not a safe solution in a storm situation.
     It is also useful to have a food inventory system that allows you to calculate what provisions remain otherwise you may end up without vital ingredients for certain dishes. Mireille used a simple note book that indicated both the quantity and location of each food item. Location is important as you do  not want to have to search the boat every time you cook a meal. The location of most of the provisions was under the bunks in each cabin in order to keep the weight low in the boat. Tins and bottles were stocked in large square padded freezer bags which could be pushed into the spaces under the bunks. This allowed more storage than if we had used rigid square plastic crates. The frozen food supermarket cashier in Monaco was rather surprised when we went in and purchased 16 large padded freezer bags of 30 liters each.
     If you ever have to provision for this type of voyage do not forget that taking along food that you really enjoy can provide a welcome relief when the going gets tough. We also took along Coca Cola and other soda drinks and lots of chocolate bars which although they are not necessarily healthy options are very good at keeping you awake and alert during rough night conditions.They are also excellent for receiving and improving relations with customs and immigration officials who come on-board.