Remember that $247.5 million convention center hotel the mayor wants to build? Well, the TriCounty Lodging Association thinks its revenue projections don't reflect "Portland Market Realities," and has done its own calculations showing projected income 29 to 50 percent lower than being forecast by the hotel's supporters. Build it privately, or get someone to cover the risks, they say, in a letter sent Monday to Adams and Metro Regional Council President David Bragdon.