I agree the best option is a small reverse osmosis water maker. The distillation bags were about $30 and merely required a little sunlight, or heat of the day, and some brackish water.
I used a similar method when traveling in the remote bush of Oz. All that is needed to create fresh water from a saltwater source is a bucket, a cup, a small rock or fishing weight and some cling film.
Here is a product which employs the same technology, but comes ready made WaterconeÂ® The Product
Of course if you are on the boat and your water supply becomes contaminated at sea, you can distil via condensation, a lot of water as long as your stove is working and you have a pot or pan with a concave lid.
I have tried to find the distillation bags I referred to above, but it seems the suppliers in Oz have stopped supplying them. However, the following is available on eBay HTI Seapack KIT Emergency Desalination Purification Filter Clean Water Htisp | eBay
Fresh water is vital to life and I can't imagine going to sea without a system, primitive as it may be, to back up water tanks in case of contamination, and in case my katadyn water maker fails.
For a lot of information on distilling water from the sea, Google or search YouTube for emergency desalination.