Thanks. I do know what a preventer is. So it is a good strategy to haul in the main under a windy run and using a preventer to protect from an accidental jibe?
I wouldn't necessarily call it a good strategy. At best, it's a temporary strategy. If the wind is building or is already overpowering the boat, best to reef that main. When in doubt, reef. It's easier to do it earlier than later.
I normally only employ the "over-trim-the-main" strategy in moderate conditions when I want to slow the boat down (like when approaching a dock under sail from upwind, or waiting for another boat to catch-up, or trying to avoid crossing a start line early). It can be dicey to employ it for very long in heavy air -- even with a preventer rigged -- when the best solution is to reef.
On another subject, is a broach happening any time we are perpendicular to the wind with the sails close hauled (for example when making a mistake similar to mine above) or is a broach happening when the boat accidentally rounds up due to being overpowered by wind and/or waves?
What is the technical difference between rounding up due to weatherhelm and a broach due to weatherhelm?
Thanks for all the help. Eric
Rounding up occurs when the center of effort on the sails shifts too far aft or outboard, usually when the mainsail is overpowering the helm. A little rounding up is normal when sailing upwind in puffy conditions -- it's the natural tendency of the boat. But severe rounding up is generally undesirable, especially on a downwind leg -- it slows the boat and can put it into a squirrelly oscillation, and can even result in a collision if another boat is nearby. But rounding up does not always result in a broach.
Broaching is when the boat goes so far over on its side that it loses rudder control. A broach most often occurs during a round-up, but it can also occur when bearing away if the sails are not sufficiently eased (like your situation above, although it sounds like you didn't have a drastic or full broach).
If you poke around a bit, you can find lots of photos of wild broaches, and most of them show racing boats that broached under spinnaker. Usually these broaches result from the overcanvassed boat first rounding up in a puff, at which point the forces on the huge spinnaker are no longer pulling the boat downwind, but instead are inducing excessive heal. It can be wild and scary, especially if the boat oscillates. Good to avoid.
Rounding up a bit at times -- not so bad.
Rounding up a lot, almost losing control -- Undesirable, re-trim sails or reduce sail area.
Broaching and losing rudder control -- to be avoided. If this is happening too often, maybe get a more experienced sailor to come out with you on a blustery day for a few pointers.