I have previously got seasick a couple of times when sailing in the Baltic Sea. Thus, I was also a little bit worried about this, since I knew that at North Sea and Skagerrak we would probably experience worse conditions in terms of sea state. Luckily, we did not experience any gales at offshore and although the waves at Skagerrak were higher than we have used to in the Baltic Sea, they were also longer. The steep waves result in uncomfortable movement of the boat, especially when going upwind.
Causes of seasickness
Seasickness is caused by the conflicting sensory inputs to the brain; i.e. your eyes are telling that the world is staying still, while the ears tell a different story. One of the most interesting evolutionary explanation for this is that the brain interpret the conflicting signals as hallucination and start a vomiting reaction to get rid of the cause of poisoning.
The key thing for preventing seasickness is to avoid those conflicting signals. Usually seasickness attacks when going down below. Staying on deck and keeping your eyes on the horizon is often the best prevention method. Furthermore, steering the boat forces one to concentrate on every wave so the movement of the boat is not unexpected.
However on longer journeys, one eventually has to go indoors to cook food, to go to the toilet or to get some sleep. This is often when the problem start. When cooking food for instance, it is important to frequently watch out from the window. Cold sweat is often the first symptom so it is important to recognize that and immediately turn eyes out of the window. Keeping head down is the worst position so that should be avoided. I have for example got seasick when searching something that has fallen on the bottom of the fridge. Preparation is the key: food can be made already on the harbour and stored to a place that is easily accessible.
Keeping eyes closed when staying or moving inside of the boat can also be helpful — at least Minna found this method useful. If the seasickness has already struck, laying down face upwards, eyes closed in the center of the boat (saloon bunks are the best) is often the best remedy. Body can then get used to the movement of the boat without getting those conflicting signals from the eyes.
Heaving-to is a good method to make the boat's movement more comfortable and to give the crew some time to rest. It can also be used to ease the motion of the vessel for cooking onboard for example.
Prevention is the aim also with medication — most of the drugs will be most effective when taken 5 to 10 hours before going out to the sea. Treating seasickness is more difficult after the symptoms have already started. This is also true with the acupressure bands applied at the wrist. I have tried them a couple of times without remarkable success. However, no single drug or treatment is effective for everybody, so it is important to try to find one that works for you.
Onboard, we have always Marzine (cyclizine) and Scopoderm (scopolamin) in store. Both of these have turned out to be effective when battling seasickness. Marzine is a non-prescription drug in Finland and it has low incidence of side effects. However, it is not sold in UK anymore due to the hallucinatory properties. We have not found any remarkable side effects with Marzine. Scopoderm skin patch is a widely used and effective prescription drug for treating seasickness. The major disadvantage of this drug are its side effects. I have not used Scopoderm, but Minna reported a very annoying dryness in mouth. At higher doses it may produce even hallucinations. Therefore, we prefer Marzine in normal conditions.
The natural product most used for treating sickness is ginger. In a couple of studies they have found it to be superior to placebo. The good thing with ginger is that it has few if any side effects. However, we have not tried it but would be interested to hear comments on ginger or other seasickness remedies? By the way, feel free to comment in English, Finnish or Swedish! Some other languages might get more difficult for us...
Read more on Noel Dilly's article "Seasickness remedies" on Adlard Coles' Heavy Weather Sailing (6th edition)