Great to get so many responses. I have good news. I bought some 3" angle iron and screwed it to the cracked part of the strongback. It turns out the strongback was not warped, just bent at the cracked part. The crack was kind of a double crack on one side causing a bend rather than an angular break. Once the angle iron was in place it is straight as an arrow as checked with a string strung across the station molds. Sorry for not responding to all. I was very busy trying to get things ready for the strips, but I did read all responses and you all gave great advice.

HOWEVER>>> I am going to make a frame for building which is staked into the ground and braced by angle braces also driven into the ground, just until I get the hull done. The strongback will be screwed to this. When I flip it over, however, I may tether the boat when not working on it! Maybe they need to come up with a new weather warning flag with a picture of a kayak wrapped around a tree to warn builders of high winds. It could be flown from the roofs of woodworking shops as opposed to near the water, since that's where we will be most likely to see it! Or maybe a weather broadcast bulletin "This station is conducting a test of the emergency kayak broadcasting system. Had this been an actual emergency you would have been advised to move your kayak into the living room and send your wife on a vacation for the next couple of weeks. This is only a test."