This last summer, our Hunter 260 (2000) developed a leak in the transom area. It was most apparent when healing quite a bit with a lot of people on board. I recently removed the rub rail from the transom of the boat at saw a pretty substantial crack where the deck and hull come together. This photo shows the portion of the crack just below the rudder post.

I called Hunter to ask about the fix they have listed on their web page. It was specifically for a bow deck separation problem. Apparently one person drove under a bridge and the act of the mast hitting the bridge pealed up the deck from the hull at the bow. Their fix strengthens this area. The engineer I spoke with looked at my picture and recommended that use a tool such as Dremel to cut into the crack area, only taking out the prior marine putty, but only going 1/4 to 1/2 inch deep. I was told to make sure I didnt cut into the fiberglass, but just the putty. Also, it was suggested that I go passed the end of the cracks just a bit to make sure that all of the separation would be dealt with. Once this was done, use a marine putty (I will probably use Marine Tex as I can get it locally) to fill the new cut. 5200 was not recommended due to its physical nature. I guess it is fairly runny in warm weather and I would probably not be able to keep it from running out of the grove. The putty should do the trick. He said that I may have to do a couple of layers of the putty since it will shrink as it cures. Once the putty is to my liking and cured, put a layer of gelcoat on, then replace my rub rail. Id suggest calling Humter Marine prior to making any repair like this just to make sure this is appropriate for your situation. They were most helpful. John Denison adds his experience with his H26: Jim, I had the same problem but the crack was so small that we could not see it until we found water coming into and under the bed cushions thru a small hole in the glass on the inside about two feet from the battery. The water only came in during sailing, not sitting. I am assuming the extra stress of sailing opened the crack more. I used a small chisel and removed the putty from the entire bottom and up about a foot on both sides. By using the chisel I could feel whether the putty was firm, soft or loose as I chipped away. I felt I had more control doing it by hand then using something motorized that can get away from you and put gouges where you dont want them. It was loose and crumbly for a total of about six or seven feet. Believe me, as I kept chipping away I began to think I was going to go all the way around the boat but eventually the putty began to feel firm and I was able to stop removing material. But, I felt it was better to do it right the first time. I used the Bondo brand Bondo-Glass to fill the gap for two reasons. 1. Because of the fiberglass strand in the product it stays where you put it better. 2. It has greater strength because of the glass filler. I filled almost to the top and then used either marine tex or gelcoat to cover, I cant remember. It has been two seasons and I have had no problems with the fix.