Could have saved yourself a little time, by re-purposing the boat rack into a new wood shed! I've been pretty lucky with the elm I've split too - but it's mostly been fairly small, very straight, and very dry. Those strings make me think maybe it was a little tougher than ash though. Nice work!
You stood on the top of the shed and cut the top of that elm off with a pole saw? That sounds like quite the job to me..... My luck and that elm top would have hit me square on the head and then my fall off the shed would have broken the boat rack.
It did get a little tedious making all the cuts so that the pieces weren't too large. I figured the small pieces would have a better chance of fitting within the rack as they fell, plus if they did hit the rack they wouldn't do as much damage. I was lucky the tree just about had the perfect lean.