Denise knows what she's talking about. The Chessie typically gets well into the 90s for extended periods, and the heat radiates through the coach roof into the cabin. A portable AC isn't enough to cool it. If you intend to spend time on it in it's slip, I'd negotiate with the seller for a price reduction to cover at least part of the cost of installing an onboard AC unit. He's selling a boat that lacks an onboard AC where one is needed. That's a negative against the market value of the boat that justifies negotiation....air conditioning would be the biggest advantage to have, unless you really really love hot hot humid stagnant weather.