I was curious about power outages as well, and why tugboats aren't required for all container ships that navigate under bridges. I'm not arguing that tugboats MUST be mandated; just wondering about the cost/benefit analysis. This claims that power outages are more common now (but doesn't cite sources/stats) in areas (specifically California) where diesel fuel is required, rather than bunker fuel: https://baykeeper.org/news/column/tugs-test-towing-giant-shi... It also makes it clear that relying on tugboats to be on standby and "swoop in to the rescue" is seriously wishful thinking where bridge safety is concerned. This article from 2019 is about a power failure due to an Oil Mist Detector that didn't have a "harbour mode" option of keeping the engine running at reduced RPM so you can still maneuver. It also shows the link between engine failure and a need for tugboats under "lessons learned":
"– Although it is tempting to free harbour tugs as quickly as possible, in the restricted waters of a small port their assistance can be invaluable should something go wrong."
On the other hand, what safety or economic issues do tugboats cause? It will probably become a topic of discussion or investigation at least.
