AS I said previously "This one APPEARED to be solid, no stress cracks, rust stains etc"
I spoke on the phone with the owner, he struck me as a honorable man.
If the boat was not what it was portrayed to be, I haven't (and wouldn't) given him any money until after inspection. I would go down there fully prepared to walk away. It would have been a quick overnight vacation with my wife.
You said the seller sent you another email back shortly after rescinding your offer... did he give you a reason? Or did he sell the boat to someone else? If he sold the boat to someone else, you can't really blame him, or at least I couldn't. For me... it's a first come, first with cash or other form of payment, type of thing. Nothing personal, but as they say "A bird in the hand is worth two in the bush" or in terms of fishing "A fish on the boat is worth two in the water". When I was in the process of trying to sell my last boat, I had so many people that "were serious" and wanted to come take a look at it. Some of them would come up with excuses as to why they didn't email/call you back, others just simply ghosted you. So for me, if someone shows up with cash or another form of a legitimate payment, I honestly don't think I could turn them down because someone from out of state, and even out of the country, says they'll buy the boat from me.
I try to give someone the benefit of the doubt and take them at their word... but coming back down to reality, you simply can't trust and rely upon everyone to follow through with what they say they're going to do. I had so many people making me offers over the phone or via email and telling me they wanted to buy the boat and they all fell through. I was about to pull the ad out of frustration with all of the tire kickers and low-ballers when I finally had a serious buyer come and buy the boat from me. That's the reason why the company that I bought my boat from said they only do in person transactions. Because they've been screwed over too many times in the past with people calling from out of state saying they want the boat, then they hold onto it for a couple of weeks for them, and then come to find out the potential buyer couldn't follow through for one reason or another. And they had to give them their down payment or deposit back. Which just allowed them to miss two weeks of where they could've sold the boat to another potential or serious buyer. I was annoyed with their reasoning at first as I live out of state from where I bought my boat, but I definitely now see why they do it that way.