I agree it's likely just hairline cracking in gel coat surface layer. Our previous 2003 248 had some hairline cracking in the steps and walk thru windshield area. We thought it was from the heat generated by the medium tan color gel coat, it can get pretty hot!
Our 2004 298 doesn't have any hairline cracking though with the same color, so perhaps it's just the luck of whatever batch of gel coat they prepare at the boats manufacture. I wouldn't worry about structural issues from it, just not great to look at for sure. It always bugged me a little on the 248 we had.
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2004 Four Winns 298 Vista
"Last Minute"