rgranger, you ask a fair question so i'll give you my opinion. very simply, bridges can create very flukey winds and usually do. canals between two different bodies of water can create unpredicted currents and often do. so what is my issue as seen in that video. if you watch the video from the south side of bridge you will see that the boat is the last through the bridge and the bridge closes right behind him. the bridge span closed blocked all the wind propelling the boat. anyone sailing around bridges will understand such. if you want to sail through a bridge you need to have a means to create way at all times. the closed bridge stopped that. the prudent sailor knows this before trying this stunt. seamanship to me means that you are prepared to deal with a given situation.
bridges, especially that one, are known for flukey winds. canals are unpredictable too, especially that one. good seamanship dictates a backup plan. in the video that sailor had no backup plan while doing a stunt in a dangerous location. all sailors doing that stunt should have the engine running while showing off.
i sail through bridges daily. my engine is on just in case.
he should have known he would loose way. he should have been in control. had he had his engine on he might have been able to deal with the new wind blast.
so what's my lesson for the sailors on this thread. bridges are very dangerous. use extra caution. he should have known this. having not been prepared he put his crew in danger.
very poor seamanship in my opinion. his poor skills are right there on video.
my $0.02