I agree with this. I am wondering if boat is an abstract class and ship is an implementation.

I think boat is a flexible definition and our view is one valid way to look at it, which the author of the article also shares.

This is my position although instinctively I’d want to require the ability for a person to sit because I haven’t considered windsurfers or kite-boards to be boats.

I think the definition is somewhat flexible.

What would you call a surf or kiteboard instead?

Disclaimer: being subjective here and not too attached to the opinions, I waiver between words having independent meanings or defined by uses (a more Wittgenstein-esque approach, at least at my limited level of understanding)

I think that those could be grouped together but would require a new category that may or may not include water skis or wakeboards. Another condition i was thinking about placing on boat was a steering mechanism akin to a rudder but then realized rowing shells often don’t have those although I’d consider them boats.

I was inclined to agree with you, but research suggests 'boat' specifically refers to a small vessel. A ship is not just a large boat.

Word research?

The dictionary

We must have looked at different dictionaries.

Sure, and it could be argued that "literally" means "figuratively", but should it?

Depends on if you're talking about a class or an object.

What about a hovercraft

A hovercraft full of eels?