I have an older allwelded hull. It has longitudinal braces but not cross braces. The bottom of the hull is slightly concave between the braces but It appears the braces are still level left to right. My question for all you boat builders and others, do I need cross braces or is the hull still gonna bend between those braces over time with hitting logs etc?

I guess the better question is, do the bends hurt performance etc? I know hooks front to
back are bad

Its one of those things that we have to see.... the concave affect shouldnt hurt your running.. Though, if it is flexing it WILL break your welds at some point..

Question for you Uncle J, if I decide I want the hull "fixed" what's the solution? Do I beat the hull flat and hve braces added or is it better to cut off the bottom and let u put me on a new 3/16 one? Or is that more expensive than it's worth?

Just beat it straight and add some ribs. Its more work putting a new bottom on a boat than building one from scratch. I actually pulled the double bottom out of my boat today and beat a bunch of hooks out of it. Ill be adding some bracing in between every brace thats in there.