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Anchor Rodes
Selection of anchor rodes should be based on existing and potential anchorages, boat windage, and displacement. Just like anchors, no one rode will work in all anchoring situations.
RODE TYPES
All nylon rodes: - Place less load on the anchor and boat because of the amount of stretch inherent in nylon.
- Are quiet and easy to handle.
- Are easier to replace if in remote cruising grounds.
- Anchoring rode is available in either three-strand or double braid.
- The breaking strength of double braid rode is greater than three strand, doesn’t "hockle," but has less elasticity and is more disposed to chafe.
- Nylon’s lightweight and ease of handling is ideal for small boats, lunch hooks, and spare anchors.
- The biggest drawback to nylon rodes is chafe. If a nylon rode is used, chafe gear is essential in rough weather or for prolonged use.
All chain rodes: - Used primarily in coral and rock bottoms.
- Under wind loading may become bar tight and place a tremendous load on the boat and anchor.
- Usually necessitate a windlass, which together with the chain, adds considerable weight to the bow, affect the boats performance, and produce a "hobby horse" effect in lighter displacement performance cruising boats.
- Chain Types Available:
- Proof coil chain is sufficient for most anchoring uses.
- BBB chain fits windlass gypsies better and is stronger than proof-coil.
- Hi-test chain has a higher strength to weight ratio than proof coil.
Chain/Rope Rodes: - Provide a compromise to all chain or all nylon rodes.
- The nylon portion will absorb shock, but chafe guard is needed where it passes through the bow roller or the chock.
- A length of chain, equal to or greater than the boat length, is connected to the anchor, usually by a swivel. The chain is connected to the Nylon rode either by splice or shackle, and is laid on the bottom to manage chafe.
SIZING RODES FOR WIND LOADING
The chart below is a guideline to wind loading for an average low profile boat. | Boat Size | Load at 30 knots | Load at 60 knots | | (In Feet) | (In Pounds) | (In Pounds) | | 20 to 25 | 500 | 1,950 | | 26 to 30 | 700 | 2,800 | | 31 to 35 | 900 | 3,600 | | 36 to 40 | 1,200 | 4,800 | | 41 to 50 | 1,600 | 6,400 |
NYLON
Below is a general selection guide for cordage size, based on premium New England Rope. The working load is accepted industry wide as 25 percent of the breaking strength. Consult each manufacturer for the recommended size in its product line. Rodes should be sized to working load and not breaking strength.| | Braid | 3-Strand | Size
(in Inches) | Breaking
Strength
(lbs) | Working
Load
(lbs) | Breaking
Strength
(lbs) | Working
Load
(lbs) | 3/8 | 4,700 | 1,175 | 4,400 | 1,100 | 7/16 | 6,600 | 1,650 | 5,900 | 1,475 | 1/2 | 8,500 | 2,125 | 7,500 | 1,875 | 9/16 | n/a | n/a | 9,400 | 2,350 | 5/8 | 13,500 | 3,375 | 12,200 | 3,050 | 3/4 | 19,400 | 4,850 | 16,700 | 4,175 |
CHAIN
Below is a general selection guide for chain size, based on working load. | BBB Short Link | High Test Link | | Size (Inches) | Working Load (lbs) | | 1/4 | 1,250 | 2,600 | | 5/16 | 1,950 | 3,900 | | 3/8 | 2,750 | 5,400 | | 7/16 | n/a | 7,200 | | 1/2 | 4,750 | 9,200 |
TIPS All parts of a rode should be matched to an equal or greater working load, including chain, rope, swivels, shackles, and thimbles. For instance, if the required working load on a rope/chain rode is 1,200 pounds, a double braid nylon rope size would be 3/8 inch, while using three strand the working load size would increase to 1/2 inch, and BBB chain size would be 1/4 inch. The swivels, shackles, and thimbles should also have working loads of a minimum of 1,200 pounds. Size one anchor rode to cover worst condition loads, which may be 60 knots of wind. Size two or more rodes, each, for 30-knot wind load. Scope is normally defined as the ratio of the water depth to anchor rode paid out. The water depth should include the height of the bow above the water and tidal range, if any. The optimum scope is 7:1. In eight feet of water, with the bow five feet off the surface of the water, and a two-foot tidal range, scope should be approximately 105 feet. This average will depend on whether all chain, all rope or a rope/chain mix is used, and the wind and sea conditions of the anchorage. Connect the chain to rope with a splice, eliminating the use of shackles and thimbles. Connect the chain to the anchor with a swivel. To connect an all rope rode to an anchor, a variety of options are available.INSTALLATION
Connecting chain or rope to the anchor, and chain to rope requires knowledge of splicing but can be accomplished by the average skilled person with minimal tools. Toolbox: - Seizing wire, where shackles or swivels are used
- Pliers
- Swivels or shackles
- Thimbles for rope
- Whipping twine for finishing rope ends
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