Rule 19 question

As Yellow has the choice which side they pass of the obstruction then the correct tactical choice would be to pass ahead as long as they can do so without impinging red. The rules say if they choose to pass astern an inside overlapped boat is then entitled to room. We come back to 19.2b..... 

I certainly wouldn't fancy sitting on a PC trying to sort that out! Case 11 in the casebook may provide some guidance though. I guess it may hinge on whether a line of Stv tackers would be considered a continuing obstruction in this case. As the OP pointed out there was sufficient space behind the second Stb boat for both boats to pass. 

I would say that Blue going through the gap between red and green is a risk that Yellow has to take. If blue didnt pull it off then they failed to keep clear.

On congested 'round the cans' dinghy courses this happens quite a lot. I usually make a call as to whatever will lose me the least time (or gain me the most time). Usually this is the option where there is less messing around with other boats.

D'oh schoolboy error there from me, should have checked that particular definition.  

Either way, subject to 19.2b and the timing of the tack of Green I still think Yellow is required to give blue room. I do think 19.2b is unlikely to feature as well given that we are talking about 40foot boats under spinnaker so unless they had just rounded a mark this is unlikely to come in to play.

It is because Yellow has the choice which side of the obstruction to pass. As she chose to pass astern of Red she must also allow room for Blue to pass astern (Case 11). 

As she cannot now go through the gap because it was not big enough for both boats she effectively has no choice other than to pass astern of Green as well. 

She cannot choose to pass ahead of Green as Blue in taking the room she is entitled to in order to pass astern of Red. So she either needs to pass astern of Green as well or take herself and Blue across the bow of Red (a risky proposition).

In theory both boats would pass astern of Green but Blue could elect to go through the gap as long as she keeps clear Green.

I think that sounds about right.

The thinking man would have seen this developing and Yellow might have gone a bit lower a bit sooner to pass astern of Green and thus minimise the loss or perhaps make a gain as thy come back up to their correct course after the duck.

That's the problem. 

Personally, whatever I decided, I'd send it upstairs to the RRC under 70.2 for confirmation. 

Agreed