Being sea sick (motion sick) is the first ailment most sailors and passengers on ships experience. The movement of the waves can affect people the moment they board the ship at the dock. In most cases, the body will adjust to the constant motion of the sea and the symptoms will fade. In some people, the continual vomiting will cause dehydration and could eventually lead to death. Below is a description of sea sickness and treatments written in 1855, from the book, A Collection of Documents on Spitzbergen & Greenland, edited by Adam White (QH11.C651855).
Between Hitland and Spitzbergen it is to be observed that here the waves of the sea run longer, almost as they do before the narrow channel between England and France in the Spanish Sea (and what hath been observed heretofore of the rowling and tossing of the sea, belongeth properly to this), with a continual tossing of the ships, which maketh the men sea-sick.
The vomiting and sickness is attributed to the sea water; but it really proceedeth from the great and continual motion of the body, when oftentimes we are forced to creep on all fours.
Neither meat nor drink tasts well, the head akes and is giddy, and they are always reaching to vomit. Costiveness of the body doth generally accompany this distemper, and the urine is highly tinged. I reckon it no more than if one is not used to ride in coaches or wagons; only that it is always accompanied by a bad stomach and restlessness.
The best remedies for this distemper, I believe, are aromatics chewed in ones mouth, as cinnamon, cloves, galangal, ginger, nutmegs, and the like. Many think to drive this distemper away with fasting, but they will find themselves mistaken. Some drink sea-water, and believe that will make them vomit, which notwithstanding is not occasioned by the sea-water, but by the loathsomeness thereof.
To take away the ill-taste out of ones mouth, in my opinion, the best means is to eat and drink plentifully, it easeth quickly; neither ought one to sleep too much, but keep in the air, and look into the wind, and to walk up and down in the ship is also very proper.
The author of this was insightful for his time. Symptoms of motion sickness include: not feeling well, nausea, vomiting, headache, and sweating. Motion sickness happens when one part of your body, such as your inner ear, senses movement, but another part, such your eye, does not sense it. To relieve the symptoms while on a ship, you can stay on the deck and look to the horizon (or into the wind as stated above), or lay down in the center of the ship where the motion is felt less. Many people have a variety of remedies for motion sickness, but the only tried and true method is to get off the ship!