Modern sprit rigged boats carrying asymmetrical spinnakers, like OUTSIDER, rarely round down to leeward. Leeward round downs usually happen to symmetrical spinnakers when the spinnaker pole is squared aft in big breeze.
A leeward round down results when the helmsman gets too far by the lee, and the spinnaker overpowers the rudder and pulls the boat over to windward. This undesirable maneuver can happen in an instant, as the below video shows.
Two unpleasant things are likely to happen as the boat spins to leeward and the mast goes horizontal: The first is the spinnaker pole goes into the water, often breaking the pole. The second is the main boom jibes at a high rate of speed, potentially causing serious injury to the rig and/or crew.
A third thing can happen when the pole goes in the water. The compression of the pole sideways onto the mast may break the mast.
Last, on a leeward round down, crew can be thrown over the side. WILDFLOWER once rescued three crew from a Moore 24 who had been pitched overboard and left behind by their boat during a leeward round down.
We are fortunate to have a 5 minute video of a Farr 40 in the recent San Francisco to Santa Cruz Windjammers Race. At 3:38 the Farr does a round down in a 35 knot puff while planing at 18 knots. The boom goes vertical, then jibes as the boat is thrown on its beam ends.
https://drive.google.com/file/d/0B0R-zXyxEWb6Y25OTmthWmNQNmM/view?pli=1
A short while earlier the driver had called for spinnaker down. But the crew was frozen in place, and nothing happened. Then as the boat began its round down, the driver called for the afterguy to be eased. But that didn't happen either. The starboard side trimmer was busy holding on for dear life. Had the afterguy been quickly eased a few feet, before control was lost, the situation might have been saved. But things were happening very quickly.
Farr 40's carry smaller fractional spinnakers as well as masthead. This may have been a situation where the masthead spinnaker could have been switched for a fractional several minutes earlier, as the breeze began to increase into the 30's.
An "outgrabber" is one of Stan Honey's favorite things and pulls the spinnaker sheet outwards and stabilizes the spinnaker while spreading its foot. On the Farr 40, and other boats, an outgrabber can be simply rigged using a clew reef line from the boom end and snatch block.
Congrats to the crew of the SSS OUTSIDER for keeping the front end aimed downhill and winning this challenging race down the Coast. And then coming back 24 hours later, 80 miles away, to compete in the Jazz Cup.