A little additional information (or entertainment), the tariff rates on products from China vary depending on the good. This article describes how the actual tariff ranges from 0% to 245% depending on the product -
The tariff rate on Chinese imports can be as high as 245% or zero, depending on the type of product that is being imported.
www.nytimes.com
I spoke with a major boat manufacturer this week who told me the net tariff on boats built in China is now
171.5% 
(he also quipped 'it might as well be 10,000%').
I was going to make a joke that 'it could be worse, could be 245%' but it doesn't apply. Once the price to consumers reaches an unmarketable level, the actual 'number' of the tariff becomes irrelevant.
I know little about the ‘foreign flag’ issue that’s been extensively discussed other than what I’ve read here. FWIW a friend of mine who is Canadian suggested it’s more complicated than some may think, or the term is misused. To “foreign flag” a boat it would mean that you do not US Document it but instead put it on the Canadian Registry which is Canada’s equivalent. In Canada you can only register a vessel if you are a citizen of that country. The way the big yachts do it is to form a company in someplace with loose regulations, like Micronesia or Aruba, and then flag the boat as a corporate vessel. Then you’d need to deal with the paperwork for annual cruising permits etc. as a foreign flag corporate vessel operating in U.S. waters (and hope that some software geeks involved with the U.S. government don’t come up with some sort of system that cross-references cruising permit applications with IRS, Social Security, Medicare, etc. or other databases to ferret out U.S. citizens who might be doing this to evade taxes).
I was told you could U.S. Document a boat and take delivery in Canada. But that would only buy a year since the boat would have to leave Canadian waters within 365 days. As soon as you cross the border you’d need to import the boat into the US. You could take delivery of a US Documented vessel in Canada, pay Canadian duty + Provincial State Tax on the boat (around 25%), get Canadian vessel license numbers (like state numbers in the U.S., costs $10 filing fee), put them on the bow, and be fine — as long as you never cross the border into the U.S., when you would need to pay the import (tariffs) fee. It might be worth the gamble if you think (hope?) the tariffs on Chinese products might be lifted during the next year, but it still seems to work primarily for those close to Canadian waters (Washington and Pacific North West, and northern Maine, seems easy; for boaters in the rest of country, not so much).
FWIW and YMMV. Like most things involving taxes and evading them, it depends on how good your lawyer is, and how much risk and hassle you're willing to take.