. . .multiple anchors, of the longer type, are needed with two in front and two aft, with lines over the hulls between each set.
Keeping the boat secured to the trailer may not be enough, as one boat flipped with trailer attached.
I think that is an extreme measure. Remember that the boats with masts down, and secured to their trailers, didn't move at all. Those included a Taipan, H-16, and A cat.
My boat flipped while attached to the trailer, but the mast was up.
