Anchor Rodes & Chain
How To Choose, Information
The selection of anchor rodes for your boat is of primary importance even if all your outings on the water last only a few hours. If your engine dies or any other emergency arises, knowing that you can drop an anchor and secure your boat is a necessity. Choosing anchor rodes should be based on your current and potential anchorages, your boat's windage and its displacement. And just like anchors, no one rode will work in all anchoring situations.
Best rodes for your Boat are essential insurance for a safe and successful cruising. Lack of confidence and worry over the set of the anchor are not only guaranteed to spoil the next day cruising and sightseeing, they will also cause disenchantment with the cruising lifestyle.
Anchor Rodes These should be all chain, or a combination of rope and chain.
On our Bruce main anchor we have 300 feet of 5/16-inch, high-test chain. Our storm rode is 80 feet of 3/8-inch chain and 300 feet of octoplait rope.
An all chain rode for the main anchor is considered a must in the Pacific and Indian Oceans to avoid coral chafe on the rope. The chain should be marked with color coded paint . After 3 years the chain will need to be re galvanized to protect it from sea water or when exposed to the weather.
The anchor chain is the basic component of the anchoring system which will consists of a combination of the following parts:
Anchor Chain: basic link between the anchor and the vessel. Chain is desirable for it's durability, strenght and weight. Weight of the chain aids the natural burying design of the anchor.
Anchor Rope: a part of the anchor chain may be replaced by a strong nylon rope. This is easier to handle and due to it's elasticity, better suited to absorb shock loads while the the vessel is riding on the anchor or pitching and straightening out the chain. On the other hand an all-rope anchor rode is unsuited for rocky bottoms where it will be destroyed quickly due to chafe. All anchor rode requires more scope to prevent the anchor from braking out.
Anchor Snubber Line: by using anchain anchor rode which - under strong wind conditions - may be pulled straight tight, a nylon rope of 5 to 20 m should be used to absorb the tugging on the anchor chain.
There are three different rode types to consider, each with its advantages and disadvantages: all-nylon rope, all-chain and a combination nylon rope/chain rode.
Three-strand twist, single and double braided nylon rope make excellent rodes.
The inherent stretch in nylon places less loading on the anchor
Nylon is quiet and easy to handle.
It’s easier to replace in a remote location.
Nylon is lightweight and its flexibility makes it easy to handle and stow, so it's the best choice for small boats, lunch hooks and spare anchors.
The biggest drawback to nylon rodes is chafe. Chafe gear is essential in rough weather or for prolonged use.
The light weight allows boats laying on an all-nylon anchor rode to “sail” around their anchor and offers little catenary (horizontal pull) to help the anchor set properly.
When selecting between three-strand twist and braided nylon rope, consider these characteristics:
Three-strand twist nylon rope costs less than braided nylon, has
more elasticity, and is more chafe-resistant than braided nylon.
Braided nylon is more flexible than three-strand, has a higher breaking strength and doesn’t hockle (kink) like three-strand twist.
Stainless steel chain
is available at a price but is considered by most offshore sailors to be impractical; moreover, stainless steel is only stainless when exposed to air, so submerging it for long periods will cause corrosive decay.
Galvanized /High Test/ Grade 40 chain
Fabricated from high-carbon steel with a higher breaking strength threshold than BBB. High-test is also lighter than BBB - by 50% - so you can either carry more of it or you can carry the minimum and save a lot of weight. Because high-test chain has grown in popularity, most windlass manufacturers sell their products with a standard high-test gypsy.
Carbon Grade 30 chain
Proof coil is the least expensive form of low-carbon steel chain on the market. While its rated breaking strengths are similar to BBB, proof coil has longer chain links and these do not fit into the gypsys of most modern windlasses. Moreover, under extreme loads, proof coils longer links have a higher tendency to collapse than either BBB or high test. Good for fixed moorings, proof coil is not the choice for a cruising boat.
All Chain Rodes - Advantages and Disadvantages
As with nylon rope, there are advantages and disadvantages to all-chain rodes.
Chain is nearly impervious to chafe and is the best choice for use in rock or coral bottoms.
Under wind loading, the chain can become bar tight and place tremendous loads on the boat and anchor.
Chain is heavy and usually necessitates a windlass, which adds even more weight to the bow of the boat. This may produce a "hobby horse" effect in lighter-displacement boats.
There are four types of chain: BBB, proof coil, high-test and stainless steel.
Proof coil is sufficient for most anchoring uses and is the least
BBB chain fits many windlass gypsies and is stronger than proof coil.
Hi-test (HT) chain has a higher strength-to-weight ratio than proof coil or BBB, allowing you to use a smaller size to reduce the weight of the chain.
Stainless steel chain is expensive, but its corrosion- and chafe-resistance provide longer life.
The best compromise between an all-chain and all-nylon rode is a combination rope/chain rode. The chain is connected to the anchor with a swivel or shackle, and is joined at its other end to the nylon rode, usually by another swivel or shackle but sometimes with a splice. Unless you anchor primarily in coral or rock, the combination rope/chain rode is all you need for most anchoring situations.
The rope/chain rode has many of the best characteristics of both all-rope and all-chain rodes. The chain provides catenary weight, exerting a more horizontal pull on the anchor, and withstands most chafe from the bottom. The nylon rope adds the necessary shock absorber, lessens the total weight and is easier to stow. The length of the chain is dictated by your boat and the depth of water you normally anchor in, but many use a chain length equal to or greater than the boat’s length as a rule of thumb.
The working loads
The chain, rope, thimbles and shackles or swivels should all be matched to the same working load limits (WWL), not breaking strengths. The working loads are derived from wind loads on your boat (see the tables below). For instance, if the required working load on a rope/chain rode is 1,200 pounds, the recommended double-braid nylon rope size is 3/8". For three-strand the working load size increases to 1/2" and BBB chain size is 1/4". The swivels, shackles, and thimbles should also have working load minimums of 1,200 pounds.
Just as with an all-nylon rode, chafing gear is needed where the nylon rope passes through the bow roller or the chock. If you use a rope-to-chain splice to accommodate a windlass gypsy, check ona and around the splice periodically for chafe. Chafe may occur during cyclical loading caused by gusting wind and/or wave action.
Chain comes with its own set of problems, as noted above. On many modern boats, the weight of the chain in the fore peak will alter the way the boat handles. There are few ways to combat this problem:
- use high test chain with better strength to weight ratio
- when going to sea, move the anchor and chain to a cockpit locker
- move the anchor locker aft, right over the keel if possible
- carry only the minimum length of chain in the fore peak with an extra length stored low in the middle of the boat to be used in unusually deep anchorages
Size, Dimensions, Working Load and Weight Chain
Chain is made if a series of connected chain links. Chain size referres
to the diameter of the link material, but chain size is often also
a trade or product name. A 10-mm chain from the European continent
may be selled as 3/8" chain on the American and Europa continents.
Remember, there are some different standards on chain link dimensions in the world!
Boat Anchor Buyer's Guides- Advantages and Disadvantages