However, at 0:33, H7 rounds the offset and M87 (and another boat on port) are already in the frame - about 3 boatlengths away. H7's only way to avoid collision is to head up - and instead, they bear away.
At time 0:33, M87 (Port) was still sailing a course (or could turn to a course) to sail behind H7 (Starboard). M87 does not turn in front of H7 until 0:36.
H7 was not obligated to anticipate M87's turn-down and attempt to cross. She had every reason to expect M87 to avoid her. See ISAF Case 27, which states "a boat is not required to anticipate that another boat will break a rule".
Watch the port boat behind M87 and the two starboard boats behind H7. They managed to avoid a collision, why couldn't H7? Because he had his head in the boat - when there were not one, but two port boats on a collision course.
I have watched the video and did not see another boat on a collision course with M87. There is another boat that could have read-ended H7 if she turned down, but she did not.
"Not reasonably possible?" Not when you t-bone someone dead square amidships at a right angle - and when there are other boats that manage to avoid a collision in similar circumstances.
Yes. I do not think it is reasonably possible to turn a 28ft boat that is going over 7kts 90 degrees within a 6ft radius in one second in a seamanlike way given no time plan the maneuver nor inform the crew .
I'm very well aware of 14(a) and Case 87. Take a look at Case 123. This one doesn't pass the sniff test when you look at the video.
I've looked at Case 123 and don't believe it applies. At time 0:33, which is when you say H7 needs to react, it is not "clear to a competent, but not necessarily expert, sailor...that there is a substantial risk of contact". At that time, M87 could still pass above H7. She doesn't commit to the cross until time 0:36.
I thought for sure you'd refer to Case 26
Have you determined from the video evidence that there was damage or injury? It isn't clear to me that there was either. Even if you feel H7 broke rule 14, she might be exonerated under rule 14(b). Oh, and by the way 14(a) is the exception part of the rule, stating "need not act to avoid contact until it is clear that the other boat is not keeping clear".
Regards,
Eric