Well I don't see how some fossils of bones millions of years old leads to the conclusion that dinosaurs didn't have the manual dexterity and intelligence to build boats, so I guess the possibility remains open.
Actually, biomechanical analysis of skeletal remains can give quite a bit of insight into the range of motion of various body parts as well as brain size and structure. Granted, brain size alone doesn't necessarily say much about intelligence, but relative size to the rest of the body and the structure of the brain can provide enough information to help make an educated guess. Just remember that dinosaurs didn't need to be smart. They just needed to be smarter than the competition (predator or prey).
Any 'educated guess' we might make based on brain size falls squarely in favour of the intelligence of dromaeosaurs, because the EQ of the average Deinonychus comes out at roughly 5.8, far, far higher than any living non-human animal today. The ratios for its smaller descendants, Adasaurus and Dromaeosaurus, are probably even better.
As for 'just needing to be smarter than competition', this is not what determines the intelligence of a predatory animal at all, you are simply completely wrong on this point. Lions and prehistoric humans both hunted antelope. By your faulty reasoning, lions and people ought to be at the same intelligence level, since both are 'smart enough' to overcome their prey. I take it you don't claim that lions are as clever as people?