text: OK, I've sort of got the idea. Geograph has a lot of good pictures of the building, but unfortunately it looks as If the latest aerial imagery we have dates to Sept. 2012. This makes it rather harder to update accurately. I'll see if there are anything in recent OSGB Open Data. Given Plas Heli's somewhat complicated multi-role purposes it will be easiest to map as a named building. The sailing club can just be marked by a dot (node) inside the building outline. It wont show up, but would be available for searches (e.g. all sailing clubs in Wales).