in or on a boat

[phoebemia]

In Kid's Box, Level 1, Cambridge University Press.
The same kind of boat, sometimes it's in the boat, sometimes it's on the boat. What's the difference?

 

[phoebemia]

Could anyone help with this question?

 

[5jj]

I think that if we have a deck to walk on, we are on a boat. If we haven't, as with rowing boats, canoes, sailing dinghies, etc, we are in them.

 

[jutfrank]

I can't see the picture very well, but I suspect the people's sitting position on the edge of the hull led the writer to prefer on instead of in in this case. They're not really 'in' the boat in this picture, as far as I can see.