A 12" jackplate will not stress the transom any more than an 8" in my opinion. The splashwell design of a Cobra was a poor design to begin with and made for a weak upper transom. Bass boat manufacters became wise to this weakness and began to create a concave splashwell area instead of the squared style. This new style strengthens the upper transom area and less cracks form because of it. The new style has less 90 degree angles which often have difficulty flexing properly. Cobra redesigned this area as well on their last production of boats. In light of all of this. I believe that you are going to get some superficial cracks in the gel coat because of the design no matter what plate you put on the boat. I run a 12" plate and had tiny cracks in the gel from flexing. The cracks were only skin deep and were not causing the transom harm. I had them repaired and later found that most of the cracking was due to too much gel coat being used in that area. This causes the gel to be brittle and have poor flexing characteristics. After some glass reinforcement and the proper application of gel, I have had no cracks.
