Pretty common occurance on a boat that gets run hard. I have cracks in both support bar welds for 6 years now. Keep meaning to weld them...hasn't happened yet. At a minimum, drill a small hole on the end of each crack. If doing so stops further cracking, your good to go except for the cosmetics. If the crack continues to enlarge, you'll have to get it welded, and possibly braced to repair the damage