I use 5/8" braided dock lines and have not had any issues with breakage and limited chafe. They are large enough that when they start to chafe I can see it and have them replaced. I found that 1/2" line had too much give (elasticity) and had to be replaced more often.

I have used 5/8 3 strand nylon for years with out issue. If a tropical storm or worse is forecast to hit the area I will then double up for that period of time.

5/8" here too.

Mike

I have about 8 dock lines; all 5/8" braided and various lengths depending on where being used.

In 2004 during Hurricane Charlie, which had 178 mph winds, I had eight 1/2 inch twisted nylon lines on Caprice here in Punta Gorda, Floida. One line parted. I had two lines tied to one 8 inch piling that where tied to two different cleats on the sailboat and this piling broke. The piling was only about five years old and in good condition.

Since then I put in 10 inch pilings with a Slide Mour system. According to the dock builder this system only requierss 3/8 braided line fastened to the two slides. However, I use 1/2 inch braided Stay-X lines. Also I have two saftey lines that just hang slack "Just In Case" tied to land anchors.

Hurricane Charlie was the only hurricane to hit Punta Gorda in 49 years, but we had a fewl hurricanes that pass by out in the Gulf of Mexico about 100-200 mles off shore giving us 50+ miles an hour winds. The Slide Mours worked well.