A crash gybe is when the mainsail unexpectedly and violently swings over to the opposite side of the boat. It most often happens when the wind suddenly shifts to the leeward side, sending the mainsail suddenly to the windward side.
It's a shock under any circumstances. But in a VOR 65 (65.6 lwl) it is particularly complicated. A running (movable) backstay supports the mast from the windward side. In a strong breeze the canting (swing) bullet keel is extended as far as 45 degrees to the windward side to stabilize the boat. In a crash gybe (used to be called a Chinese gybe) the boom swings over to the formerly windward side and strikes the running backstay. That makes it impossible to release the backstay in order to let the sail out and let it flap like a flag. Only when the crew has set the backstay on the new windward side can the now leeward backstay be loosened.
Complicated enough in a boat lying on its side -perhaps in the dark- but the VOR 65 has a canting (swinging) keel which is now on the wrong side, threatening the boat with capsize, not just a `knockdown'.
Starting at about 9:45 you will see footage of two crash gybes - one in the dark, the other in daylight. The narrator - staring about 12;30 demonstrates what happened on a model.
