Hi- I recently had allergy patch tests completed after a very nasty allergic reaction and found out I'm allergic to a preservative- isothiazolinone compounds and also some fragrances, limonene and linalool. I had never heard of it, but it is responsible for an epidemic of allergies and dermatitis.
Its a preservative and used in anything from toothpaste to washing liquids, toiletries, shampoos, printing inks and also paints. Some sufferers can experience a reaction from being in a room that has been painted with a paint containing it. It's suspected that many people suffer mild issues and dont know they have it.
Heres a link to a page I follow- It may be completely unconnected but it might give you an idea of things to try- or consider what is different between home and boat- do you have different laundry liquids etc. Good luck
https://www.facebook.com/pages/Allergy-to-Isothiazolinone-Methylisothiazolinone-and-Chloroisothiazolinone/307128722674171