Having been in a similar situation myself when i was confortably clearing the starboard boat then a windshift when and sent it all awry. Now in my case the SB boat heads up and proceeds to hurl abuse at me. After the race a calmly showed him rule 16.2 which governs right of way boat changing course. He was a little sheepish after that. Regardsless of anything else ALL boats are duty bound by COLREGS (which override RRS in some areas) which say a collision should be prevented if it can be. So my conclusion... The guy on Port was in the wrong and should have taken a penalty (I believe even if it is right on the line you can still take the turns and then re-cross the line, possibly best to make the RO aware of what you have done). The guy on Startboard if he headed up and hit you on the rear quarter was also in the wrong and should also have required (the first word from your mouth should have been Protest, nothing less will suffice or the Protest Committee can throw it out on a technicality). This way when you get ashore you can quite legitimately fill out your protest form, depending on facts found he may be liable for your reapir costs (most insurance companies will not even entertain a blame on damage when racing unless there is a protest).