I'm certainly not a class purist since I only race PHRF but I would recommend against the modification described for all the same reasons listed in the other responses. You are looking at an siloated design element of the boat - Johnstone considered the entire hull shape, keel, sail plan, etc. when designing the J30 - modifying your boat would mean finding a like minded individual who belives in "innovation" like yourself. Likely you would find that people would shy away from your modified boat once you attempted a sale... I certainly would. One last BIG issue - I assume you race PHRF since you aren't a "purist." Your local PHRF guys will hammer your rating if you effect such a modification. In my area, it seems to be an annual ritual for PHRF to consider lowering the rating of the J30 - your mod would provide ample opportunity for PHRF...
