In reply to ZacMoss:
Steve King, in my caving club, did some research into washing caving ropes. About 15 years ago. He then analysed the molecular structure of them ( he worked at Harwel).
One of his conclusions was relevant to this discussion. The ropes became stiffer after washing but this could be alleviated by adding fabric conditioner (NOT detergent). He surmised that washing ropes removes any lubricating chemicals present from manufacture - hence the rope doesn't handle very well. Using fabric conditioner helps the fibres to slide over each other, restoring the nice handling of the rope. It didn't affect the strength (which he subsequently tested).
So if you've washed it loads and it still feels stiff, it's not salt crystals - it's a lack of 'lubricant'. Try another wash with a bit of conditioner!
And no, I've not a clue which one to use!