1st off, the new superfuns are great.
But i agree with Jeffy, isn't this a warranty issue?
If not, i fixed two cracks down the centerline of my new Superfun using the technique here:
HOW TO: Repair a cracked boat
I know you're thinking there's no way duct tape can work but read through it first. I fixed mine about 3 weeks ago while waiting to pick up my new boat and it's been holding up with no leaks in some really shallow rivers with lots of sharp rocks.
I guess your other option is Dave Frank's technique. I must say I'm really curious about it also. I didn't think you could weld or patch crosslink, just linear. Dave, do you mind putting up some info about that?