This is probably a scam ... they get a lot on that website and some people must get caught. Try asking some tricky questions about the boat or ask about payment and it will probably become obvious. I think they hijack other people's ads, or old ones.
As Whitelighter says it's a very niche thing but always remember ... the scammers do advertise real boats - they hijack other people's ads. If you do follow this one up (I wouldn't personally!) do check out any odd payment instructions! ... Only trying to be helpful.