My personal preference is 3/8” solid braid nylon. I use this on my 19’ fiberglass I/O boat and I have found it to be more that effective. For me, it’s the right size and strength to give me confidence in anchoring.
Some say that they prefer a ½” or even 5/8” thick rope. The reason that some prefer that thickness is, it is easier to grip in their hands when pulling the anchor up.
I completely understand that and agree if I were have to pull my anchor up by hand, I would opt for something thicker than 3/8” rope.
When I get asked, what rope size do I need for my anchor, the first question I ask is, are you using an anchor puller with a buoy ball attached? If so, then you probably don’t need anything thicker than 3/8”, since your anchor puller is doing the pulling of the anchor off the bottom. All you are pulling in is slack rope, so you wouldn’t need that grip as you would pulling it by hand.
To see how we use the anchor puller system with a buoy ball, check out the video below.
Another thing to consider is, the thicker the rope, the more drag it creates when anchored, as well as the added weight that a thicker rope has. You may or may not notice it when anchored, but it is something to consider.
The best way to figure out what rope size you need for your anchor is, find out what the others are using in the area you want to anchor in that are using similar boats and equipment. You don’t need to reinvent the wheel, use what is known to work and adjust from there, based on your needs.
If you don’t currently have a setup that works for you in the area you want to anchor in, stop by your local outfitter that offers anchoring equipment and ask them what people are using in your situation. That should help you answer the question on what rope size do you need for your anchor.
Hope this helps!