Drew -
Although I can’t speak to the issue of liability insurance, I think that I can help you on the lawsuit issue.
The short answer to your question is “it depends.” Basically, it is always possible that someone could file a lawsuit and try to haul you into court. As long as their suit had some “colorable claim” (meaning that a judge, when viewing the facts in a light most favorable to the plaintiff, decides that there is a legitimate basis for the lawsuit) and it wasn’t “defective” (meaning that it was properly prepared, filed, etc.), they would at least be able to get you into court. If their lawsuit failed to state a colorable claim or it was defective, you could get it booted without having go through the headache of litigation. In either case, however, you are probably going to be running up at least a small amount of legal fees and/or experiencing the angst/anxiety/whatever that accompanies being sued.
Having said that, unless you manufacture your boards in such a way as to make them abnormally dangerous (e.g., retractable piano wire leash built right into the board, leading edge of fins made of stainless steel and honed to a razor’s edge), you probably don’t have much to worry about in the way of liability. Put differently, there are a number of defenses that would be available to protect you (e.g., assumption of liability by the “injured” plaintiff).
So, my $.02 is - YES, there is always a theoretical risk that someone could haul you into court if they were injured while surfing one of your boards. And YES, you would probably incur at least some small amount of legal fees in defending yourself (although you may be able to recover those from the plaintiff if you prevail, depending on the state you live in). HOWEVER - and this is a big HOWEVER - that is a risk that each of us faces as part of a very litigious society shaped (in my opinion) at least in part by an overly paternalistic federal government. Think about it - do we REALLY need warning labels on handguns to tell us that someone could get hurt if you shoot them?!
Anyway - political rant aside - my advice is that if you want to manufacture and sell your boards, go for it. Don’t let the risk of lawsuits/liability stop you from doing what you want to do. In reality, the likelihood that you will ever be called upon to defend a lawsuit is probably very, very slim. If it makes you feel better, print up some type of warning label and stick it on your boards. Just collect a few warning labels from sporting goods products and rogue the language from them to make your label.
It occurs to me that there is an analogy here - perhaps a strained analogy - between your dilemma and surfing a new spot. Specifically, when you are sitting there watching perfect peelers at a new spot, you naturally feel a bit of anxiety about paddling out b/c you don’t know what to expect. Are the locals gonna hassle me? Are there rocks or other hazards that I can’t see but should know about? Etc. etc. But counterbalancing the anxiety are those perfect waves! So what do you do? You paddle out, of course!