The vang isn't that useful close hauled. Your mainsheet has more downward force on the boom.
I don't agree. In big air you can dump the mainsheet without having the mainsail power up. Of course you can drop the traveler in a puff also, but that may be either harder to reach or take too long to think of. As seas build you'll want the sail flat even as you ease it out as the angle of close-hauled changes.
An effective preventer needs to be led from the end of the boom to a point well forward of the mast, in my opinion, and when it's led back to the cockpit, it's an arrangement easily adjusted on any point of sail off the wind...
Exactly. I've run the numbers a bunch of times and there is no substitute on any boat I've sailed for a preventer that runs from the boom end to the bow and back to the cockpit or stern quarter.
The preferred method of rigging a preventer is to take it forward to a turning block and then back to a quick release in the cockpit. The line should be stretchy enough to absorb an impact should the boom hit the water, but no so stretchy that it will allow the boom to reach within 30-40 degrees of the centerline of the boat.
I strongly disagree with having a stretchy preventer. The loads increase dramatically over a system that holds the boom as steady as possible. You have to look past static loads to dynamic ones.
Let your attention wander and get a little by the lee, and that little "topsail" will start heeling you to windward, toward what we in dinghies used to call the "death roll" or the "burnout". And that heel to windward will immerse your port side more, and move your Center of Effort to the "wrong" side of the Center of lateral resistance. Presto! you've now got a much bigger case of lee helm you may not be able to cure, and crew (if not clicked in) losing their grip and tumbling to leeward, and a crash jibe at about the same time.
To quote one of my favorite movies "the big boats get the glory but the small boats make the sailor." I'll take a dinghy sailor on board a delivery in a second. I can teach systems pretty fast. You can't teach the kind of understanding nolatom describes on your way out an inlet.
I've found that accidental gybes in air up to the mid 30s, result in only a few inches lateral boom movement if the preventer is vertical prior to the gybe and snubbed such that there is no slack.
You'll have to help me understand what you describe. You want the preventer as near perpendicular to the boom as you can. Perfect isn't attainable of course but it is much more horizontal than perpendicular, and much more longitudinal than transverse.