You probably did not have the trailer back far enough into the water. The boat needs to be put on the trailer as close as you can get to the bow roller. Make sure the centerboard is all the way up in the centerboard housing and you will hear a klunk when it is up all the way. Rudder needs to be up when you pull out. You will not be able to get it all the way to the bow roller but as close as possible. With the water ballast opened, you will want to pull partially out of the water to allow the ballast to drain. In some cases it was reported the wing nut on the threaded rod had been loosened but the rod had not gone down and that is due to the gasket stuck to the bottom of the hull. Simply put your foot on it to go down. It will take about 2 1/2 minutes for the water to escape the ballast tank. Pull the boat up and trailer up. On a flat surface, if the bow of the boat is several inches from the bow roller, I taught my customers to pull forward and brake suddenly to get the boat to move forward on the trailer, then tighten up on the winch strap. It may take several times doing that. Remember the weight of the boat is on the bunkboards and there are several things you can do like adding to the bunks something that will allow the hull to move better on the bunk boards. When done, allow the centerboard to rest on the keel tray but do lock the line anyway to prevent the centerboard coming down when launching the boat the next time. I suggest a strap over the back end of the boat and twist the strap on both sides to prevent the wind from slapping the strap against the hull. Also, put the safety chain on the bow eye in addition to the winch strap and if too long, simply twist the chain to shorten it. I also added a line to lock down the winch handle as that can come loose when traveling. Saved many a boat over the years with that little trick. Go about 10-20 miles, stop and recheck your tie downs as well as the winch strap as things do loosen up in the first few miles of travel.
You will find useful information in the archives on this but if you want to call me and discuss in detail, feel free to do so. Send me a private email and I will send you my phone number but remember I am 3 hours behind you being on the east coast.