There are many different opinions about seasickness. Some like the homeopathic remedies like the sea bands, ginger, etc. Others tend to trust modern medicine. As to over the counter, Bonine (which is actually Meclizine HCL) is the same drug as is the prescription drug Antivert (this is also the same formula for the anti-drowsy Drmamine)is very effective for most folks. Since you only need one pill (25mg) per day, you can take the pill at bedtime, and it will probably not make you drowsy during the day. There is also a more effective prescription product called Transderm Scop (which is scopolomine) which is a patch you wear behind the ear. This product can have some side effects (some have trouble reading when on the patch) but its very effective.
Personally, after more than 30 years of cruising (and also using small boats) we (wife and I) have found Bonine to be good enough for us (they have this over the counter stuff at most pharmacies