X2… buy and use any rope you like, as long as it is made and meant for use as “anchor rode.”
http://www.boatus.com/boattech/articles/rope.asp
I would actually suggest starting with picking out the type of anchor you want? All anchors have one or more drawbacks and you need to use the anchor most successful for your needs – be it whatever? Match the anchor to your intended use (lunch hook, working, or storm anchor) and determine the minimum holding power you need and the type of bottom anchoring to. I actually carried all three types of anchors and overkill really is always best.
“However, always remember that there are few certainties when it comes to anchoring and overkill is always best. And this table is for guidance only. Always get the recommendations of the product manufacturer:”
[TABLE="width: 100%"]
<tbody>[TR]
[TD="colspan: 6"]
Boat Dimensions Horizontal Load (lbs.)
[/TD]
[/TR]
[TR]
[TD]
Length
[/TD]
[TD]
Beam (Power)
[/TD]
[TD]
Beam (Sail )
[/TD]
[TD]
Lunch Hook
[/TD]
[TD]
Working Anchor
[/TD]
[TD]
Storm Anchor
[/TD]
[/TR]
[TR]
[TD]10’
[/TD]
[TD]5’
[/TD]
[TD]4’
[/TD]
[TD]40
[/TD]
[TD]160
[/TD]
[TD]320
[/TD]
[/TR]
[TR]
[TD]15’
[/TD]
[TD]6’
[/TD]
[TD]5’
[/TD]
[TD]60
[/TD]
[TD]250
[/TD]
[TD]500
[/TD]
[/TR]
[TR]
[TD]20’
[/TD]
[TD]8’
[/TD]
[TD]7’
[/TD]
[TD]90
[/TD]
[TD]360
[/TD]
[TD]720
[/TD]
[/TR]
[TR]
[TD]25’
[/TD]
[TD]9’
[/TD]
[TD]8’
[/TD]
[TD]125
[/TD]
[TD]490
[/TD]
[TD]980
[/TD]
[/TR]
[TR]
[TD]30'
[/TD]
[TD]11'
[/TD]
[TD]9'
[/TD]
[TD]175
[/TD]
[TD]700
[/TD]
[TD]1,400
[/TD]
[/TR]
[TR]
[TD]35'
[/TD]
[TD]13'
[/TD]
[TD]10'
[/TD]
[TD]225
[/TD]
[TD]900
[/TD]
[TD]1,800
[/TD]
[/TR]
[TR]
[TD]40'
[/TD]
[TD]14'
[/TD]
[TD]11'
[/TD]
[TD]300
[/TD]
[TD]1,200
[/TD]
[TD]2,400
[/TD]
[/TR]
[TR]
[TD]50'
[/TD]
[TD]16'
[/TD]
[TD]13'
[/TD]
[TD]400
[/TD]
[TD]1,600
[/TD]
[TD]3,200
[/TD]
[/TR]
[TR]
[TD]60'
[/TD]
[TD]18'
[/TD]
[TD]15'
[/TD]
[TD]500
[/TD]
[TD]2,000
[/TD]
[TD]4,000
[/TD]
[/TR]
</tbody>[/TABLE]
Concerning the rode size, that has to do with the “Working Rode Sizes” and suggest using the chart below. If your boat is 15' - 20' you are fine using ¼ inch. That is within the “Suggested Minimum Working Rode Sizes”:
[TABLE="width: 100%"]
<tbody>[TR]
[TD="colspan: 5"]
Suggested Minimum Working Rode Sizes*
(For winds up to 30 knots.)
[/TD]
[/TR]
[TR]
[TD]
L.O.A.
[/TD]
[TD]
Beam (Sail )
[/TD]
[TD]
Beam (Power)
[/TD]
[TD]
Nylon Rode
[/TD]
[TD]
Chain Rode
[/TD]
[/TR]
[TR]
[TD]10'
[/TD]
[TD]5'
[/TD]
[TD]5'
[/TD]
[TD]125’-3/16”
[/TD]
[TD]3/16”
[/TD]
[/TR]
[TR]
[TD]15'
[/TD]
[TD]7'
[/TD]
[TD]7'
[/TD]
[TD]150’-3/8”
[/TD]
[TD]1/4”
[/TD]
[/TR]
[TR]
[TD]20'
[/TD]
[TD]8'
[/TD]
[TD]9'
[/TD]
[TD]150’-3/8”
[/TD]
[TD]1/4”
[/TD]
[/TR]
[TR]
[TD]25'
[/TD]
[TD]9'
[/TD]
[TD]10'
[/TD]
[TD]150’-3/8”
[/TD]
[TD]1/4”
[/TD]
[/TR]
[TR]
[TD]30'
[/TD]
[TD]10'
[/TD]
[TD]11'
[/TD]
[TD]200’-7/16”
[/TD]
[TD]5/16”
[/TD]
[/TR]
[TR]
[TD]35'
[/TD]
[TD]12'
[/TD]
[TD]13'
[/TD]
[TD]300’-1/2”
[/TD]
[TD]3/8”
[/TD]
[/TR]
[TR]
[TD]40'
[/TD]
[TD]13'
[/TD]
[TD]14'
[/TD]
[TD]400’-5/8”
[/TD]
[TD]7/16”
[/TD]
[/TR]
[TR]
[TD]50'
[/TD]
[TD]14'
[/TD]
[TD]16'
[/TD]
[TD]500’-5/8”
[/TD]
[TD]7/16”
[/TD]
[/TR]
[TR]
[TD]60'
[/TD]
[TD]16'
[/TD]
[TD]19'
[/TD]
[TD]500’-3/4”
[/TD]
[TD]1/2”
[/TD]
[/TR]
</tbody>[/TABLE]
*Suggested sizes assume fair holding ground, scope of at least 5:1 to 10:1, and moderate shelter from high seas. Boats that operate generally in shallow waters, as on the East Coast of the United States, may get by with shorter rode lengths.
And… Yes, there is really nothing wrong with using a larger anchor and/or rode (if you want a rode easier on the hands remembering that larger rode is harder to handle and takes up more space)! Here is an excellent article outlining the above:
http://www.boatus.com/boattech/articles/anchoring.asp