To my way of thinking there is a continuum between highly tacit stuff and clearly explicit knowledge.
Tacit knowledge is closely related to intuition, gut feelings, compiled experiences and skills. This tacit stuff is very hard to explain, it comes from exposure, arises out of repeated learnings, consists of deeply held feelings and beliefs. Tacit knowledge allows us to reason without logic, to act without reflection and to make sense of new situations.
Implicit knowledge sits in the middle. Here we are able to model, explain, draw, surface, share insights and explicate beliefs. This often requires time, deep reflection, dialog, introspection and mulling around.
Explicit knowledge is documented, illustrated, captured, stored and retrievable. It takes many forms from transcripts, to business rules, from detailed definitions to evolving scripts e.g. such as we see in wikipedia or video sequences.
Not everyone will impute the same meaning to explicit knowledge,personal or group interpretations are context and time dependent and biased by each individuals own tacit knowledge.
The key is not finding a clear definition of explicit or tacit but wrestling with the meaning, exploring examples, situating knowledge along the continuum. For what is tacit now may become explicit tomorrow and what is implicit can easily return to the tacit well or source