Anchors and Anchor Rope; How To Select

Anchors and Anchor Rope | How To Select

There’s little doubt that an all chain anchor rope is the very best solution in most cases. Chain is much stronger than any nylon anchor rope, it doesn’t suffer from chafe and the weight of the chain works as a shock absorber, reducing the loads on the boat if there is any surge or other shock load on the anchor rope system.

However, an all chain rope is very expensive, it’s very heavy (and it’s in the bow, where you least need it), hard to handle, it probably requires a chain windlass to retrieve it and it needs a snubber so that any chain shock load is absorbed before it’s transmitted to the boat.

The best compromise for a sailboat is probably laid nylon line with 20-30 ft of chain before the anchors end. Nylon stretches by about 25% at 50% of its breaking strength and recovers from heavy loads better than braided line. Practical Sailor recommends New England Rope’s Premium 3 strand nylon.

What Size Nylon Anchor Rope and Chain?

This depends to a great deal on where you usually anchor, the bottom conditions and the worst weather conditions you expect to encounter.

As a starting position you might consider:

For a boat length 20-25ft: ½ inch nylon rope with 20 ft of 3/16 inch high test or BBB chain

For a boat length 26-30ft: ½ inch nylon rope with 30 ft of ¼ inch high test or BBB chain

For a boat length 31-35ft: 7/8 inch nylon rope with 35 ft of 5/16 inch high test or BBB chain

If you’re headed offshore, go up at least 2 sizes in both rope and chain.

A tip. Buy domestic made chain. Imported chain may or may not be of the quality specified and your boat is worth a whole lot more than 30 ft of chain.

anchor_ropeFor your primary anchor rope you’ll need at least 10 times the depth of your deepest anchorage. So if your deepest anchorage is 20 feet you’ll need (20 x 10) = 200 ft of anchor rope. This allows for a 7:1 scope on your anchor rope in fairly shallow water (20 feet). As your anchors depth gets greater, you can reduce the scope somewhat, even down to 3:1 in very deep water.

The anchor rope to chain and chain to anchor connections should be by shackle, at least one size larger than the chain (i.e. ¼ inch diameter chain needs a 3/8 inch diameter shackle). The shackle pin must be securely moused with monel wire. The nylon anchor rope should have a metal thimble spliced into the end connecting to the chain.

The bitter end of the nylon anchor rope (the end connected to the boat) should not be connected directly to the boat inside the chain locker. There should be a tail of light line connecting the end of the anchor rope to the chain locker. This tail should be long enough to reach the bow roller from the chain locker. The reason for this is so that you can cut this light line if you ever need to get rid of one of your anchors quickly in an emergency.

Anchors | Anchor Rope

Here’s where we get into dispute territory. I know every sailor has an opinion on the best model for a given bottom condition and will argue all night about the pros and cons of different models.

I’m going to slide out from under by using the results of Practical Sailor’s extensive testing of anchors under $200. No correspondence will be entered into ;-)

Practical Sailor has conducted extensive tests over the years on many different makes and models of anchors suitable for sailboats in several different bottom conditions. For anchors costing less than $200, their conclusions are:

Anchors Guide

Name
weight
sand
mud
combined
sand
rank
mud
rank

holding

rank
 
Barnacle
28#
16
9 tie
12 tie
355#
9
800#

1

577#
4
Bruce
22#
3
2 tie
1
307#
11
550#
8
429#
10
Bulwagga
17#
1
8
4 tie
816#
2
680#
3
748#
2
Lewmar Claw
22#
8
2 tie
4 tie
283#
14
520#
9
401#
12
CQR
35#
15
2 tie
9
583#
3
760#
2
672#
3
Danforth Deepset II
20#
14
15
14
363#
8
640#
5
502#
6
Delta
22#
13
1
7
496#
4
610#
6
553#
5
Fortress FX-16
10#
9
13
11
471#
5
420#
12
446#
8
Hans C-Anchor
15#
17
12
15
0#
17
350#
15
175#
15
Herreshoff
17#
6
-
-
300#
12
-
-
-
-
Hydro-Dyne
10#
failed
-
-
-
-
-
-
-
-
Nautical Engineering
20#
11
14
12 tie
235#
15
390#
14
313#
14
Seagrip
33#
12
-
-
200#
16

-

-

-

-
Supermax (adjutable shank)
26#
7
2 tie
3
410#
7
430#
11
420#
11
Supermax
26#
5
2 tie
2
350#
10
400#
13
375#
13
Spade Model 80
16.5#
2
7
6
1000#
1
660#
4
830#
1
Vetus
12#
4
9 tie
8
285#
13
590#
7
438#
9
West Marine Performance
25#
10
11
10
456#
6
460#
10
458#
7

Note: the Bruce model is no longer made for recreational boats. The Lewmar Claw is a close copy.

The figures give the breakout loads for each model in the respective bottom conditions, and the rankings are out of the 15 anchors that passed the tests.

Setting rank = how quickly the seting was when under load compared to the others
For non-US sailors, the # sign = pounds weight or load.

The 22# Lewmar Claw and the 20# Danforth are quoted as suitable for a 30-35ft boat, but I think it's prudent to go one size higher than recommended by manufacturers. So I'd select the 22# Lewmar Claw for a 25-30ft boat because it sets well in any bottom material. I'd also like the 10# Fortress FX-16, which is an aluminum version of the Danforth, as a lightweight second anchors.

The Spade Model 80 are excellent aluminum plow style anchors that won this test. The shank is bolted to the plow and can be disassembled for stowage.

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