I have it in my mind to build a c-channel alum trailer next summer to replace my alum I-beam rig. Can someone give me a size of c`channel that either target or manning or another top builder has used for a mid 30's boat? 8"-10" ?

you will never know if it is to strong but you will know if is not strong enough !!!!!

There was a build thread by Zero Patience in the cig section...He built his own