SD, "fair use" is actually rather specific and I can't think of it being applied in this case. "Fair use" means that if you want to rave about a book you just read, you can post a couple of lines from it without asking permission. And, a batch more specific instances.
But when it comes to copyrighted IMAGES...taking someone else's image and using it for your own commercial purposes is simply illegal. (In the US and the other Berne signatories.) Just because something is on the web, does not mean it can be used. Just because you buy a boat, doesn't allow you to use the pix that the manufacturer uses in their brochures. Again, especially not for commercial purposes. Since his question is about using the images for his BOAT CHARTER BUSINESS...this is a commercial copyright question.
It is way safer to ask permission from the image owner, than to steal the images. (Especially when commerce and profit are involved.)
An attorney can be a good idea...but the rules and explanations of them are all on the Copyright Office web site, they were one of the first federal agencies to make real good use of the Internet.