FWIW, our 1999 boat
was re-powered in Italy
in 2012/2013. We then bought her in NZ in 2016 and imported her last year. From what I could tell in my own research
and Yanmar seem
(trust but verify) to have EPA certification
on all of their engines regardless of where sold. This may be, in part, because there are other countries that use the EPA certification
so they don’t have to write their own regulations
and do their own testing. I only really looked at those two brands because they were what powered 99% of the boats we considered. Don’t know about the Betas/Nannis/Kubotas/Westerbekes/etc. that power lots of other boats.
we bought had Perkins/Volvos that were certified compliant. They were then recalled over emissions, initially only in the US, but then in China
, and a few other places. Because we were a US boat Volvo
replaced the engines last year.
The importation process itself was quite easy. CBP has a couple of pieces of paperwork they require, plus the EPA form. The only thing they looked at, on the whole boat, was the sticker on the engines. The rest was just paperwork and $.
[Edit] one caution, the Volvo recall
was for D1, D2, (and D3?) series engines from ~2007 to ~2016. These engines have an EPA sticker but the certification was withdrawn. The recall is ended and Volvo will no longer replace the engines. So, at least technically, there is a fleet of Volvo powered boats out there that appear compliant but likely aren’t.