I can see what your saying about being a vertical support. I looked at it closer this evening. I realized that when that area was being glassed in when the boat was being made, that it bridged the corner where it cracked. The glass never got seated into the corner. If you look, you can see that the inner corner radius around the box is tighter then in the area that is cracked. I drilled a small hole in the corner where the crack is and there is a big gab between the corner glass and the bottom and side of the box and hull. I’m sure it’s been there since the boat was built in 2001. The right thing would be to cut it out and relay some glass , paint to match like you suggested. I don’t have the materials to match what the factory did I can lay glass but can’t match the colors. I don’t have a huge budget to take it in and have it done. Thanks for your help and suggestions.