NURBS help
 

i am building a car with nurbs and am having a problem, not sure wot ive done wrong, the surface just seems strange, any suggestions.

just to let you know i used birail 3+

to get a more accurate result, after i do birail or square operation, i insert a cople more Isos on the surface, then i select the Isos, then duplicate them as curves, then do a loft operation.
it always gives me gr8 results.
but from what i can see , your surface looks fine.

You want to make sure the curves that are opposite of each other have the same number of spans to get the cleanest result.

Yea, do what Mikey said. Before you birail it, rebuild the curves w/the same amount of spans. Thatll make ur mesh so much smoother. :)

the spans look like they match from looking at the pic tho

They cant, because of that double isosparm. Those being so close, means that theres uneven spans. But someone correct me if im wrong... :)

I agree with Hybrid.