How to choose your anchor rode

Anchored in South Caicos, Turks & Caicos

When we decided to buy new anchor rode, I remember the (countless) hours I spent googling something similar to: ‘thing-y that attached the anchor with the other thing-y’! There is so much vocabulary you need to know to be able to buy what you’re actually looking for and will work for your boat. So here it is with plenty of pictures and explanation so (I hope) you will have a better understanding of the whole anchor rode system.

The anchor rode

The anchor rode is what will connect your anchor to your boat. It can either be all chain, all rope or a combination of both. I will describe here the summary of what works for us on our boat. I found a great article about how to choose your anchor rode.

Anchor rode system
Ground tackle overview

How to choose your anchor rode

How to choose your rope type and size

Three-strand twisted nylon is usually preferred for the anchor rode as it is:

  • Light
  • Strong: high breaking strength
  • Elastic, which is good for shock absorption
  • It sinks
3-strand twisted nylon rope

To select your rope size, you should count 1/8″ of rope diameter for every 9″ of boat length. So, let say for a 35 ft boat, the rope size should be:

35 / 9 x 1/8″ = 0.49 or ~ 1/2″

How to choose your chain type

There are three popular varieties of chain: Grade 30, Grade 40 and Grade 43. You can buy galvanized steel or stainless steel chain (same as your anchor), the latter being more corrosion resistant but also more expensive and has a lower breaking point. The links are embossed with their grade marking making it “easy” to identify (see picture below).

G4 anchor chain embossed with “G4” grade

Anchor chain type

If you don’t have a windlass, the chain type and size doesn’t matter much. We bought some Grade 40 (or G4) anchor chain as its working load limit is twice as much of BBB so we could use a smaller chain size.

To understand the different between the different types of chain, it’s important to understand the difference between the pitch and chain size (see picture below).

The pitch is the distance between the centres of two links. If the pitch isn’t uniform, it can’t be used with a windlass.

Chain pitch

The table below is a good summary of the different chain types, grades and their uses.

Anchor chain description

How to choose your chain size

Your chain size should be half the diameter of the line they attach to so for a 1/2″ rope you should have 1/4″ chain. You could also go to your anchor’s manufacturer website and look for recommendations.

For 15kg/33lbs Rocna, the recommended chain type is G40 and size is 5/16″

These articles are great resources for more in-depth information about anchor chain: your-chain-explained-understanding-anchor-chain and how-to-pick-an-anchor-rope-size-type-length-and-more.

Our setup

On our boat, we had 125 ft of 5/16″ G4 chain with 150 ft of 3/8” spliced 3-strand nylon. We bought an extra 25ft of chain that we connected with a 5/16″ quick link as we felt we needed a bit more chain for bad weather.

5/16″ quick link to connect extra chain

And for two reasons, we prefer having more chain:

  • Because the chain is heavy (it’s also its drawback), it lays on the bottom so the pull on the anchor is horizontal (rather than vertical), which reduces the chances of your anchor to unset.
  • It also adds more weight to your ground tackle and it won’t chafe (compare to rope).
  • We don’t fully trust that splice between the chain and rope. The only way I found online to test it is by using cars!

    So why do we even have line then? I read this a while ago and it made sense to me: most people will splice some line to their chain so in case your have to free your boat from your anchor for various reasons (getting dragged towards a reef, tangled…), you can cut the line (which is a better alternative than trying to cut your chain!). Also, rope is lighter than chain so if weight is a concern you might want to use a combined anchored rod.

    As I mentioned previously, the type of chain we use doesn’t matter because we don’t have a windlass. If you do have one, you will have to find out which type is compatible with on your windlass manual. This website is a great reference if you don’t have your windlass manual.

    Without a windlass, we just link our anchor and chain with a galvanized anchor shackle (make sure you pick the same material as the anchor and chain) , one size larger (3/8″) than the chain (in our case 5/16″) and safely secured with stainless steel seizing wire. If you don’t use the seizing wire, overtime the shackle pin will eventually get loose and guess what? You might loose your anchor!
Shackle connecting the anchor to the chain

With a windlass, you should consider an anchor swivel to prevent the chain from getting tangled in shifting winds or reversing current. Don’t cheap out though as some of our friends lost their anchor because of a faulty swivel! This article is a great read about anchor swivel.

Anchor swivel
One type of anchor swivel

The anchor swivel attaches to the anchor on one end and to the chain on the other end, replacing the anchor shackle in our setup.

How to connect your rope to your chain

Now that we have our anchor, our anchor shackle (or swivel) and our chain, we need to either:

  • If you go for an all-chain anchor rode, attach last link of chain to the boat (in case you use all your chain, you want to make sure it’s attached to your boat!)
  • Splice some 3-strand nylon to your chain. There are 2 different ways to do it:
    • You can splice the rope around a thimble and then connect the thimble with a shackle to the last link of your chain,
    • You can splice the rope directly onto the last link of your chain. If you have a windlass, this is your preferred option as a shackle won’t go through your windlass.

This is a great resource that will explain how to splice 3-strand nylon to your chain and this one is a video and step-by-step description for a thimble splice. I love this website for knots or splices with its step-by-step instructions.

Rope to chain splice (left) and thimble splice (right)

I didn’t find any evidence of a rope to chain splice being weaker or stronger than a thimble splice. However, the advantage of a rope to chain splice is that it has no mechanical parts to fail or shackle pins to unscrew. In this article, there is an in-depth explanation about the limitation of the rope-to-chain splice so they recommend regular inspection and if you observe any chafe, shorten your line and splice it again!

How to attach the bitter end of your anchor rode to your boat

 

Eye bolt
Eye bolt

First you need to check if you have an eye hook install in your anchor locker. If you don’t install one and then:

  • For an all-chain anchor rode, with a shackle connect the last link of your anchor rode to the eye bolt. Don’t forget to secure the shackle pin with stainless steel seizing wire.
  • For a line/chain or line anchor rode,
    • Tie a bowline around the eye bolt
    • Do a thimble splice and connect the thimble to the eye bolt using a shackle.

West marine provides a great read about upgrading your anchor rode.

So now that you have an anchor, some chain and/or line attached to your boat, you can go out have fun and anchor! Stay tuned for our next post about Scope and chain length calculations!

 

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