How often should running rigging be replaced?
What type of line works best for a given application?
In general, running rigging should be replaced whenever it shows visible signs of damage - core hemorrhaged through the cover, several broken strands close together, "rot" from UV exposure, or green and stiff from disuse. Your sheets, control lines, and other systems should operate easily, with low friction. We discourage practices like saving old halyards to use as dock lines - a low stretch halyard used as a dock line can shock-load a cleat and cause damage to the cleat and boat.
Time to replace this...
Line can be described in terms of the fibers used in its construction, the manner in which it's put together (double braid, parallel core, single braid, 3-strand), and the qualities that result from the combination. When choosing line for your boat, it's important to consider strength, stretch, handling, and abrasion resistance. For instance, stretch is good in dock lines and anchor rode, and a little stretch is nice in sheets, but generally not so in halyards.
Standard working loads should be no more than 20% of the rope's rated breaking strength. Owners should pay attention to hardware like blocks, deck organizers, and rope clutches - they will limit the maximum line diameter.
One of the best, free, sources for starting to learn about running rigging is the West Marine catalog. Each line they sell has a description of its fiber content, construction, uses, and breaking strength. The West Advisor section often has useful, easy-to-understand information.
Manufacturers can also be very helpful - click on the links below for Samson and New England Ropes Line Selection Guides.