This issue seems to be specific to IE since it works fine in Chrome – although  I still have problems loading in FF.

I start a track replay and click on any of the view buttons to centre the boats in the viewing area

Then click in the window and use the scoll wheel to zoom in  – instead the focus moves South East.

Left click and drag, right click and drag or middle click and drag all do the same thing.

The only way to get back to the boats is to click one of the view buttons.