What type and size of rope do I need for my boat’s anchor system?

What type and size anchor rope for a boat's anchor system

If you are wondering, “What type and size of rope do I need for my boat’s anchor system?”

When choosing your rope size and type for your anchor system, there are a couple of things you should consider and we will discuss them here. But remember, these are just guidelines, not set in stone rules.

Some reputable sources say a good rule of thumb is 1/8” rope for every 9’ of boat.

Anchor Rope Sizing Rule of Thumb

That being the case, then an 18’ boat would need ¼” rope and that may very well be sufficient, but it just seems a bit too small for my liking.

Now, jump up to a 19’ boat and that would make it 3/8” rope. Now that is starting to make more sense to me and that is what I use for my 19’ boat.

You don’t hit the ½” need until you get to about a 35 – 40’ boat, unless it is a very heavy craft.

All that being said, I think that 3/8” rope is the sweet spot for most boats up to about 30’ and I would even use 3/8” as a minimum, no matter how small the boat is.

So, in determining what size of rope you need for your boat’s anchor system, I hope that sheds some light on the subject.

Now, let’s discuss the rope type that you would use for anchoring.

First off, you will NOT want a rope that floats. Ropes that float, like polypropylene, can create a hazard if you must cut your line because your anchor gets stuck or you throw your line overboard to chase a fish.

Polypropylene Rope for anchoring a boatFloating rope for anchoring a boat

If left floating, you or some other boater can run over the floating line and get caught in the prop or impeller and can be dangerous.

Nylon rope is the accepted norm for anchor line, not only does is sink, it is relatively inexpensive and elastic as well, so when a wave hits, it will stretch and absorb some of the shock, then go back into shape.

3 strand nylon is a good choice for cost reasons, but solid braid is more flexible and doesn’t cost that much more, so personally, I don’t scrimp on that.

The only downside to solid braid compared to 3 strand is, 3 strand is easier to splice than solid braid, but good knots on solid braid are more than effective, so I choose solid braid.

Well, I hope that was informative and gave you some good information on what type and size of rope you need for your boat’s anchor system.

Don’t hesitate to leave a comment below if you have any questions or other input you have on the subject.

For more information on the right anchoring equipment for your boat, visit your local outfitter or go to anchor-caddie.com today and thanks for listening!

Reviews (4 comments)

  • Anchor Caddie On

    Hi Donald,

    If you are just mooring, you could probably get away with something smaller than 3/8", but 3/8" is a good choice! You can’t go wrong with a 3/8" sold braid nylon!

  • donald ladouceur On

    Nice informative video which assisted me in my selection of rope for a mooring system on a 14 1/2 for aluminum Lund boat. Guess I will go with 3/8 nylon braid line.

  • Anchor Caddie On

    Hi Christa,

    The length of rope is not based on the length of the boat. It is based on the depth and current conditions of the water you are anchoring in.

    When anchoring, the Coast Guard recommends a 7:1 scope, meaning that if you are anchoring in 10’ of water, you would use 70’ of rope. Now this is for extreme conditions and I don’t know many people that use that much. What I see out there is that most folks, including myself, are using about 3:1 or 4:1 in moving rivers.

    In a lake condition, where there isn’t much current to speak of, you could probably get away with about 1:1 or 1:1.5, meaning if you are in 50’ of water, you could drop straight down with 50’ of rope with a little extra to compensate for wakes from passing watercraft.

    Myself, I carry 300’ of rope and only let out what I need at the time, based on what I mentioned above.

    Paul Anderson

  • Christa McLane On

    How long of a rope would you recommend for an anchor? My boat is 16 foot!

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