Water in the rudder.
I can't speak for Hilco but had the experience of frozen water eventually separating my rudder. She spent the majority of her life in Michigan through four owners, then a short stay in South Carolina and now finally in SoCal. Within a year or so of getting her, the starboard side of the rudder up to the waterline simply peeled off, held in place by mere threads, literally. The bottom, starboard four feet of our seven foot long, transom-hung rudder with foam attached, merrily floated to the surface, buoyed by that foam. We have four pair of Wilcox Crittenden boarding steps on the rudder that came into play in the moments after. I gave the helm to Marilyn and climbed over the stern and down the steps to the water line. Somehow I summoned the strength with my right arm to reach down, rip it free and in a wide arc, stowed it between the stern rail and the split aft stay. At the time we were headed toward our slip in the entrance channel of Marina del Rey so I hailed the LA County Sheriff to inform them what had happened and what I was up to while I limped back to our slip at a mere crawl. We got back safe and sound without assistance, repaired and re-foamed the rudder, all has been well since. The mirror image halves became compromised over the years, presumably due to freezing and thawing time and time again, to the extent that it finally gave up the ghost on our watch, all's well now, Glyn Judson, E31 hull #55, Marina del Rey CA