I need to do some work to my boat trailer. Tandem axle....The spring qualizers are stuck, I'm going to go ahead and R&R springs, hangers, u-bolts, the works.....

My questions it this: How do I re-align the axles, I know you can measure it out somehow, but for the life of me I can't remember how!

I replaced the springs, axles, u-bolts, etc. on my tandom trailer about 2 years ago. On mine, I did not have to align anything. I bought the same length springs and did not remove the hangers. The springs typically have a locating pin in the center and the axles have a receiving hole on a piece of flat stock that is welded to the axle. Thus, everything centers itself - as long as you don't need to remove a hanger.

If your new axles and springs don't have this locating system, you will need to measure in a diagonal pattern from side to side until you get the measurements exactly the same. You also need the lines to cross in the exact middle beween the frame. Do this for each set of springs and just keep the center to center distance between the axles the same. This is a tricky process and is much easier if the boat is off the trailer.
Ron

Trailer axles can normally only be aligned by phisicaly bending the axle. The average guy can't do it. When I worked in the trailer buisness, we either used chains and hydraulic jacks axles on the trailer or a HD press if off tyhe trailer. Measurements were taken at either the hub face or the wheel face. 1/8 - 1/4 tow in and camber is needed. IE: the measurement is 1/8" - 1/4" less on the hitch side as opposed to the rear side, and the same from the top of the hub measurement to the bottom hub measurement. We aligned hundreds of axles this way, when I worked for a trailer manufactor. I'm not familar with Ron technique but it sound like he setting it at 0 tow and camber. This will get you close I guess. Most people buy a new axle beam, measure yours from spring center to spring center and hub face to hub face and note your bolt pattern.