Several years ago, before we were aware of the easy to use and commercially available "sand anchors",
we had a problem with boats blowing around at one of our local lakes druing weekend regatta's.
One weekend in particular a mini twister went thru the fleet and several boats ended up in a pile.
After that, when the days sailing was done, not only did some of the guys drop their masts, they also added 5 to 10 gallons to each hull. given that water weighs about 8# per gallon, the thinking was that 10 gallons in a hull made it highly unlikely that the wind could lift the additional weight. Then in the morning everyone pulled the hull plugs and let the safety ballast run out onto the beach. I am not advocating this as a solution instead of a sand anchor, just offering it as an idea if you are desperate for a margin of safety and do not have a sand anchor available.
One other example, a couple of years later, I was trailering the boat between Laramie WY, and Medicine Bow WY, and we had a front quartering crosswind that was just brutal. My tow vehicle was rather narrow, and at one point I looked into the rear view mirror and the boat and trailer were flying a hull/wheel. Scared the bejeusus outta me, so after slowing down until everything was on the ground again, we stopped at the next gas station and added about 5 gallons per hull for the remainder of the trip. We didn't want to add too much weight for a couple of reasons one because of the slosh factor when changing speeds, two because of the load on the hulls where they were supported by the trailer, and three because of the load on the springs of the trailer itself. We also could have removed the trampoline, but, at the time, it just seemed like a lot less work to just add the water weight. Also, time was a consideration as it was late on a Sunday afternoon, we still had a long way to go, and Monday mornings came early after a weekend of racing.
Anyway, just thought I would share an emergency solution that has worked in the past. It is not a perfect solution for many reasons, but it could be used in a pinch.

Stephen
H-18