Early this year I crewed on a yacht that was crossing the Atlantic and all of the crew were doing this for the first time. For our leg from Lanzarote to St Lucia we had 1,000 liters of fresh water in the tanks and this with careful use would last for 30 days for a crew of five. So from a practical experience I can answer some of the questions based on our 26 days and nights at sea, living with just the bare minimum of fresh water.

We all brushed our teeth twice a day with toothpaste and salt water. This is very common practice and I've done this a few times for extended periods. I found that my teeth and gums were clean and healthy and it's something I look forward to when traveling on or near the sea.

We washed our hands after the toilet use using saltwater from the foot pump tap. Our dishes were washed with sea water every day. This includes the coffee cafetiere which was not rinsed with fresh water and we noticed no real difference in taste. We did have to use more washing up liquid than you would do in fresh water but this is normal in sea water.

Washing ourselves was another issue altogether. We had to strip down to our underpants and put on a safety harness and climb over the rail to the platform on the back of the yacht just above the water. Yes the yacht was moving at approx. 7 knots and there was not much room, but just enough to stand up. We would throw a bucket into the sea and wet ourselves and then apply soap and rinse off. It was not an easy process and you did feel very exposed as the yacht was always moving. A slip over even with a harness attached would cause an injury. We would then take time out to dry naturally in the breeze and sunshine. We tried all the soaps on board and even a bit of detergent. Liquid shampoo worked the best as it would rinse off well and not leave a residue. The down side was that we had to use a plastic container. We tried really hard to minimise our plastic and shred and compressed it. After 26 days we had the amount of plastic in the picture below for our crew of five.

We did not wash our clothes and just lived with them being dirty and sweaty. A clean set of clothes was a real treat but only lasted a few hours and then they were just like the rest of your clothes and the rest of crew. Our risk was actually drying them without them accidentally going overboard and the reality of getting them back was zero. There was also the risk that drying clothes would get in the way of the normal running of the boat, with a greater potential of initiating unnecessary problems. So for us it was that if clothing went overboard we would not alter our course. We washed our clothes after we made land. We did this by hand and rinsing does use quite a bit of fresh water.

As for pollution, well, the fact that you are using soap in the sea means that your bodily dirt is being attached to the soap lather and is entering the sea. It is a sad reality that if you want to be clean your dirt has to enter the water system, be that fresh or seawater.

To be clean you will have to spend money to generate a lather and you will pollute. If you are going to wash in seawater I would check the ingredients, and ideally for there to be nothing that you are not personally happy to put into our seas or oceans. Unfortunately they have to use the International Nomencature of Cosmetic Ingredients naming system.

Normal bar soap does not lather and what is left on your skin is hard to rinse off. This is because the seawater has approx. 3.5% Salt or NaCl and most bar soaps convert the fats and oils to soap using a lye solution that is made from water and Sodium Hydroxide (NaOH). Chemistry of soap.

So chemically soap for seawater needs to be made using Potassium Hydroxide in the Lye but this is more expensive than the Sodium Hydroxide. Liquid soaps are made with a Lye that has a high content of Potassium Hydroxide and they will work in sea water. The main issue here is that they are all in plastic containers and they can easily slip overboard.

If you are looking for a bar soap that works in seawater you need to go no further than looking at this website. Their bar soap is specially designed to work in seawater. It has a high Potassium Hydroxide content and is packaged in cardboard, so no plastic, even in the packaging glue. It has a high Glycerin content with the bare minimum of ingredients so what you are leaving behind is minimal.