I was at the Ipswich Waterfront yesterday - a few yachts with tall masts plus the following... This relatively small modest ship... in respects to above the waterline barely reaches one storey tall, yet the mast is approximately 4 times as tall... approximately 4 storeys tall. Upon our previous calculations this ship should clear the pedestrian deck... Image from Life on the Waterfront blog. As you can see these tall ships (clues in the name!) are taller than the James Hehir building at the University of Suffolk - due to perception they aren't quite as tall as shown here, however, they won't clear the Upper Orwell Crossings as planned for a fixed bridge.