Essential Safety Tips: How Much Anchor Chain Do I Need and What Size?


Having the right length of anchor chain is crucial for securely anchoring your boat. Choosing the right amount of chain for your boat can be difficult because there are various factors to consider. These factors include boat size, weight, water depth, weather, water conditions, and bottom type.

In this blog post, we will discuss how to choose the right length of chain for your boat. So, let's dive in!

1. Anchor Chain Length:

Experts recommend using a chain for anchoring that is three times longer than the water depth. This will help to keep the anchor secure in calm water. For example, in 10 metres of water, you will need to deploy at least 30 metres. This calculation provides enough scope for the chain to lay flat on the seabed, maximising its holding power. Weather and water conditions change this ratio. In windy or fast current areas, release more anchor chain to ensure stability.

It is important to consider the size of your anchor locker.When all your chain is in the anchor locker, there should be a minimum of a 30 cm of drop from the underside of the Deck to the top of the chain pile. This to ensure your windlass will operate properly and not cause a chain Jam.Check the windlass’s lifting capacity to make sure it can lift the chain and anchor's weight. Decide where you want to use your boat. Additionally, consider the usual places to anchor in that location. In safe anchorages with shallow water up to 10 metres, the chain is usually at least 50 meters long to ensure safety. For coastal or global boating without knowing the depth, typical chain length is approximately 80-150 metres long.

2. Anchor Chain Size:

The formula to calculate anchor chain size uses the length of the vessel, displacement, windage, and weight of the anchor. Generally, the boat manufacturer/designer or survey requirements determine the chain size.

Another determining factor is the grade of chain. Commercial vessels that don't anchor often may choose to use higher chain grades, this allows them to decrease weight by using a smaller sized, higher-grade chain.

While reducing weight may seem a good option, it can have disadvantages for boats that anchor regularly, as the weight of the chain plays a big part in keeping the vessel securely anchored. Heavier chain also reduces the vessel's swing while at anchor.

Typical Chain sizes used:

6mm anchor chain is typically used for boats up to 9 metres (29ft).

8mm anchor chain is typically used for boats 9 metres (29ft) up to 14 metres (45ft).

10mm anchor chain is typically used for boats 14 metres (45ft) up to 17 metres (55ft).

13mm anchor chain is typically used for boats 17 metres (55ft) up to 24 metres (78ft).

16mm chain is typically used for boats 24 metres (78ft) up to 30 metres (98ft).

20mm anchor chain is typically used for boats 30 metres (98ft) up to 40 metres (130ft).

The above sizing is a guide for typical usage and not a recommendation as to what sizes are suitable. A qualified Marine designer/architect, Marine Surveyor, or the boat Manufacturer should determine the correct size of chain.

When buying anchor chain in Australia, whether galvanised chain or stainless steel chain is used, it should meet Australian standards. The chain should be Tested, Stamped with the suppliers brand and should show the Grade of the chain, also the supplier should be able to provide a test certificate.

Whilst it is simple to purchase anchor chain online, consulting an expert in the types of chain available and ensuring your chain is high quality is a key safety factor.

If you need any product advice or have any questions about anything anchor chain related such as range of chains and suitability, anchor winches, link dimensions, hot dipped galvanised finish vs stainless steel anchor chain or how is anchor chain measured, give us a call on 0418 180 421.