[Fish53]

A butterfly knot is more easily made than in the two examples given, simply twist the head of a bight twice and pass it through the resulting opening. Where you place the twist determines the size of the eye.
By the way, doing the same with two bitter ends instead of a bight produces a carrick bend.

 

[Fish53]

Personally, I always use a bow and stern line and however many springs as required by the vessels size and the tide, also I always keep the lines on the boat, the boat is made fast to the dock, not the other way around.