Length might depend on your usual launch ramp conditions (also spool capacity). But the ramps I normally use, for instance, never require me to use more than about 5' of strap ever. I usually drive the boat right up onto the trailer to within inches of the front bump roller. And during launch, the ramp is not so steep as to have to even use the strap...I just loosen it enough to unhook, and push the boat off enough to get in if I'm alone and power it off the rest of the way. But I imagine that different ramp slopes and launch area conditions might require considerably more actual winching of the boat, and consequently more strap.