Had a good friend tell me once (very accomplished long distance sailor): Everyone gets seasick... we all just have different thresholds.
SOmoeone above mentioned diesel fumes. They get me too. Going down below and making plots gerts me in seas about 10+ for 24+ hours. I know my threshold. Once I get sick, that's it and I am usually fine.
I have found that some people are extremely sensitive to it. Medicatoins you should conider are Scopolamine (put on about 24 hours ahead of time, though some will say 6 hours early), phenegren, and valium (for vertigo). All of these are prescritpion only and docs are really careful with Valium as it is addictive.
You need to find something though. I wonder if the valium might not be the trick for you since it could be anxiety. Also, ginger snaps and peppermint are the non medicinal options. If none of this works and you are finding yourself being sick for days on end, it strikes me you have an inner ear problem or simply are one of those people that are very sensitive to motion. Can you read in a car? What about a plane?
My warning to you is that many of these meds (ginger and pepermint aside), have side effects that vary with individuals. Take them before you get on a boat to test them. DIscuss this issue with you doctor. You may have a lot of fluid in your ears that is screwing with your balance. SImple OTC meds like Alavert or Sudafed with Psuedoephedrine (can be used to make Meth so have to get from behind pharmacy counter) may help with the allergies and decongestion. Liek I said, Valium is good for vertigo and anxiety, both of which may b effecting you. If none of those meds work and you are sick over 48 hours at sea, well, I would look into a differnt type of boat - like a hard chimed boat that planes or partially planes (non-sailboat).
Anything over 48 hours sick is a danger to me. I don't even like 24 hours. On a small boat, that person becomes a real liability. You can become sick enough to endanger yourself and the crew taking care of you can become taxed and endanger them as well. Not trying to sound like doom, but I personally would not intentionally let anyone on the boat with me that got sick over 24 hours. Too dangerous for everyone involved. But you can't help what you can't help. SO talkk to your physician and start on some meds and get your ears checked out.
Thanks everyone for the responses. So far I've tried mescaline (sp?) dramamine and I think benzodrine. They all seem to help, but put me to sleep quickly and for a long time. My 'plan' is to single hand so this obviously won't work.
So I'm reluctant to try vallium too because I think it zonks me out pretty completely.
I've also taken alavert, claratin and benodryl for pollen allergies I have, and I don't *think* they work, but I usually only take them inland where the pollen is
I do get sick in a car if I try to use a laptop for too long. I don't get sick in planes, but as a child I would barf every time so I guess I'm 'prone' to getting motion sick.
I'm also pretty adverse to meds you have to apply beforehand. I mean if you are departing a trip offshore, and take that to get over the initial period, are you fine afterward or are you just delaying the sick part & taking meds 24/7 on a long passage?
I guess the bottom line is I'd hate to spend a few years fixing up a boat and then selling it the day I get to Hawaii (assuming I survive 30 days of vomit)