For definitive information on car floats check out Phil Goldstein's site.
http://members.trainweb.com/bedt/IndustrialLocos.html#unloading
The main index on the home page has the link to the loading and unloading procedures. It was a nine step process. Idler cars were not always used. The switch engine would commonly reach onto the bow of the carfloat to reach the first cut of cars and on step four. For the other succeeding cuts, the cuts served as the handle.
Ray
Any cargo ship must have its load balanced at all times
The heaviest cars must go on the centre track of three, and first. Then pick cars to go on the side away from the mooring line a partly fill the track.
Then the other side with slightly more cars, then alternate sides with short cuts of cars until the barge is full, or no more cars to be loaded.
You want the vessel balanced side to side and front to back.
Always use empty idler flats to push/or pull cars. The switching engine must not put weight on the barge.
To empty the barge, the same in reverse, half of one side, all the other, all of the centre.
Dave
Were railroad car floats, such as those in NYC and NJ, loaded according to the weight of the cars? On a three track float, was the center track the preferred track for loading?