Anchoring


This page, initially within the pages of the Banjer 37 Motorsailer's Club,
is now available in this Motorsailers & Motorsailing web site. Enjoy it!


CONTRIBUTIONS FROM READERS
You may go directly to this section by clicking HERE


ANCHORING
(Storm at Martial Bay, Tierra del Fuego, Chile)


Rules to choose the Anchoring Tackle has been, till recent times, a matter of experience and sometimes even a matter of wisdom and wishful tinking.

Rules and Regulations of the several Classification Societies allowed (and still do) for simple formulae to choose a ships' tackle, based mainly in Britany style anchors and all chain rodes. As those are empirical, based on many ship's tests and thousand of feedbacks from the industry, as well as only considering good mud or sand bottoms as those found in the charts' anchoring spots, results are quite similar from one Society to the other. Nowadays engineers have powerful and precise calculating methods, used to design, case to case, permanent anchoring tackles for big floating structures as oil rigs, etc.

Working and fishing boats usually do not anchor, simply because they do not need to, excepting in specific situations not highly demanding. So anchoring is an skill not mastered at all by most of the professionals in these fields. All fishermen I know through my professional activity only know and use the local variation of the grapnel anchor, good only for rocky bottoms.

Away from the higly demanding offshore rigs world, yatching is probably the most demanding field for anchoring techniques and equipment, because of the variety of bottoms, weather and other anchoring spots conditions. But until recent times it was based on simple 'rule of thumb' or semi-scientific methods.

The better approach for anchors manufacturers/developers was to do several anchoring tests, results varying significantly from one manufacturer to the other, because they were made under different conditions:  Bottom quality, depth, rode composition and length, etc., were not uniform, and manufactures having not standarized published data to compare their results with others'. So the only way of comparing was to perform their own testing against competition units. And some manufactures tend to 'bend' reality towards their interests and hide to the public the negative aspects of their anchors. Unluckily this still applies in many cases....

A more scientific approach is taken nowadays by designers, as well as several independent studies have being performed and released.  But again the not standarized tests conditions make it difficult to obtain general conclusions, although well stablished myths are falling quickly down. Many owners still doubt, feel confused or believe they do not have enough knowledge when choosing their anchoring tackle, being  to them the best source of information the feedback from the cruising community, through Forums, etc.

Just to try to help fellowmembers of the Banjer 37 Motorsailer Club to better choose their equipment or judge the existing one, I'll navigate through all (to me) available information, post it here, analize it, and then, with the help of other experienced members, try to arrive to some conclusions and recomendations to be used in our beloved Banjers. I'd very much appreciate all contributions.

Guillermo.


First let's have a look about what has to be taken in account when designing an anchor. I find these pages useful to this end.

Anchor design theory  
From the pages of the Dutch firm Vryhof Ankers, specialized in big anchors for the offshore industry.

Anchoring Theory - Compuserve Sailing Forum Discussion, 1997
"We are all aware that real-world anchoring is more complex than an idealized mathematical model or lab test..."

Anchor Catenary Details
"An anchor rode is not an straight link between the bow and the anchor..."
Includes an useful Anchor Catenary Calculator.


Now, we'll have a look to several anchors tests available in internet:

The Sailing Foundation Anchor Tests. Puget Sound 1995.  
"Of the anchors tested, only five passed the threshold of 1,000 lbs. and only four could arguably pass as storm anchors. The holding power of those four exceeded storm anchor requirements, but failed to do so on a consistent basis."

AVERAGE HOLDING POWER (SAND)
FX 37
3,263 lbs.
Performance 35
1,724 lbs.
CQR 45
1,304 lbs.
MAX 17
1,268 lbs.
Delta 35
 801 lbs.
Bruce 44
496 lbs.

"It would seem preferable for an anchor to not set than to set and hold at only moderate conditions"


1994 West Marine Sand Anchor tests  
"Anchors which come highly recommended, even those which are successful in the marketplace, may not perform in the real world."

1990 San Francisco Mud bottom Anchor Tests  
"These tests were conducted in order to establish a reliable, controlled database for comparing the performance of various popular recreational marine anchors in soft muddy sea floor conditions."

Here you have their results:

TYPE
WEIGHT
Lbs.
AVG.
DEPTH
MAX
PULL
AVG
PULL
MIN
PULL
SLACK
LINES
HP/LB
Bruce 44
46
25.4
300
280
250
0
6.1
CQR 45
47
22.2
525
440
400
4
9.4
Delta 35
33
24.8
625
502
200
4
15.2
H-1800
33
24.4
825
725
325
4
22.0
T-4000
30
23.0
1050
725
450
0
24.2
FX-37 32 deg.
20
22.5
1325
825
675
2
41.3
FX-37 45 deg.
20
24.8
2500
2175
2000
0
108.8
VSB-3600
28
24.6
1315
1150
2
47
WILD CARD GROUP
FX-85 32 deg.
44
21.3
1400
1200
850
0
27.3
FX-85 45 deg.
44
20.7
5150
4716
4300
1
107.2
FX-125 32 deg.
65
21.3
2500
2283
2150
0
35.1
FX-125 45 deg.
65
21.7
6600
6166
5400
1
94.9

From this Test Series, we can conclude that for soft mud bottoms, we should use devotedly designed anchors, as the Fortress FX, set at 45º. They have holding power/weight ratios around 100, which is outstanding.

On the other hand it seems to be clear that plow type anchors, as CQR, Bruce, Delta and the like, are not good for soft mud bottoms.

2003 Soft Mud Bottom Anchor test
"All of the manufacturers of these anchors recomend them for boats between 33 and 38 feet in length..."
Test Series performed by the manufacturers of the Super Max anchor, not being enough accurate, in my opinion, due to the low number of tests performed (only one per anchor!) and not rigurous enough method.

The French Regulatory anchor tests.
From the pages of Fortress anchors.


Breaking free  
"If you, like me, enjoy anchoring in those small, remote coves, you are sure to have dragged your anchor at some time : no matter what anchor you use, poor holding or strong winds will have made sure of that." (Alain Poiraud). Interesting tets series, where the setting ability of anchors on sandy bottoms was observed. Very interesting conclusions on instability of Flat Anchors.

Practical Sailor's 1999 Mud Tests  
In Mud, the CQR and Barnacle Rank at the Top of 17 Anchors

Anchor Reset Tests   ( Practical Sailor, 2001)       
Comprehensive test performed by  "When direction is reversed 140º. a third of the anchors never broke out, another third reset at some length, and two never reset".


Value guide table from Practical Sailor's 2001 tests


Yachting Monthly 2006 anchors test  (In my opinion this is one of the best set of tests, including most of nowaday's anchors)
Yachting Monthly collaborated with SAIL magazine in America to carry out the most comprehensive group test we have ever performed. Over three days in California we conducted tests on 14 anchors – a mix of traditional, proven designs, several ‘new-generation’ models and some futuristic-looking newcomers.


Well, having read down to here through all of the previous Tests reports, I feel somewhat confused. To try to help fellowmembers of the Banjer 37 Motorsailer Club to make their own decissions on what anchoring tackle(s) should be better for Banjers use,  I'll try to arrive to some conclusions, based on my own experience and knowledge, as well as on most welcome expected contributions from BMC members and friends.

Some other interesting pages related to anchoring:

Anchor rode - by Alain Hylas
"The main and ONLY advantage of the chain is that it is the only and perfect mean to avoid chafing of the anchoring rode on agressive sea beds. Except for this point, chain has all the disadvantages..."

Rope to Chain Splice Test, by Chuck Hawley
"If the chain splice is examined for chafe on a regular basis, we find no objections to the rope to chain splice from a strength reduction standpoint, as it appears close in strength to other components in the system and to commonly available nylon line."


Now, let's go on working on what is needed for Banjer sized boats:

CALCULATED ANCHOR CABLE TENSION  IN WIND AND WAVES, FOR 36' KETCHS

The following table is based on Bob Smith's analysis of the force applied to sailboats of different sizes in wind and waves based on observations in the Columbia River. Correction factor of 1.25 applied for ketch rig. (Excerpted from The Sailing Foundation Anchor Tests)

WIND VELOCITY (KNOTS)
21
24
27
30
33
36
39
42
45
48
51
54
57
60
63
RODE TENSION  (LBS)
169
220
280
345
417
496
581
675
774
881
995
1116
1244
1352
1520
RODE TENSION (KGF)
77
100
127
156
189
225
264
306
351
400
451
506
564
613
689

(Rode scope of five times depth. Boat veered 30 degree to wind)

Notice that with a 63 knots wind (Superior limit for Force 11) the rode tension (equal to wind & waves force) acting on the theoretical typical 36' ketch, is only slightly less than the Bollard Pull estimated downwards in this page for a 27" diameter propeller (746 kg) in Banjers with the Perkins 4236. This means that even with full engine throttle, a Banjer would not be able to make a headway. In real life this is even worse at sea, because waves are really much bigger than those found when the Columbia River test, where fetch was (most probably) relatively short.


The Beaufort Scale
Light Air
Light Breeze
Gentle Breeze
Mod. Breeze
Fresh Breeze
Strong Breeze
Force
1
2
3
4
5
6
Knots
1-3
4-6
7-10
11-16
17-21
22-27
Near Gale
Gale
Strong Gale
Storm
Violent Storm
Hurricane
Force
7
8
9
10
11
12
Knots
28-33
34-40
41-47
48-55
56-63
64+

The worst time for an anchor to drag is in extreme conditions. Those situations often occur at night, on lee shores or when a vessel may be surrounded by coral heads, breakers or other boats. So we have to calculate our anchor for the worst expectable conditions, let's say the top of  Force 11, 63 knots winds, as we have to put a reasonable limit, unless wanting to carry something like an oil rig's anchoring system aboard.

The tests we've seen upwards here, indicate that because most anchors do not perform well in rocky, kelp/weed-infested areas, a selection of suitability of bottom for anchoring, may be more important than selection of an anchor. Indications on nautical charts of bottom characteristics are very general. Investigation of holding ground is possible through experience and, if all else fails, experimentation. Since it is generally difficult to verify the quality of the set, the best insurance is personal experience with a given anchor design and its suitability for specific bottom conditions.

We know now what kind of forces our grounding tackle has to withstand. Now, how can we calculate what is needed for our Banjers?

I'll try to follow some recommended methods, commonly used by the boating and shipping community. But first we may have a look at the web sites linked inmediately down here, as I find they are helpful stuff to simply calculate the anchoring tackle, as well as having very interesting info.

Principles and Performance of Anchors  
Detailed information from the manufacturers of the Flook anchor. Although rigurous, is easy to follow. Includes an useful nomogram, the 'Anchor Computer'.
Fotografía de Microsoft Photo Editor 3.0
(Click on image to find it in Dunhulty's pages)

Tunning an anchor rode  
From Al's Software Sailing Page. Most useful. Most probably all you need to know about anchoring calculations, although some simple maths are required. You may download from there several useful spreadsheets, allowing you to simulate your rode configuration. Down here you'll find a link to download his Synthetic Formulae spreadsheet.

Al's Anchoring Tackle Calculator
(Click on anchor image to download it directly to your computer)


26.10.2005
At the Safe Anchoring Guide web page from Fortress anchors' web site, they provide a table to determine the holding power needed as a function of wind velocity and boat length, for average beam and windage boats:

WIND
SPEED
BOAT LENGTH in FEET. Holding in pounds
20ft
25ft
30ft
35ft
40ft
50ft
60ft
70ft
15 kts
90
125
175
225
300
400
500
675
30 kts
360
490
700
900
1,200
1,600
2,000
2,700
42 kts
720
980
1,400
1,800
2,400
3,200
4,000
5,400
60 kts
1,440
1,960
2,800
3,600
4,800
6,400
8,000
10,800

WIND
SPEED
BOAT LENGTH in METERS. Holding in kg
6m
8m
9m
11m
12m
15m
18m
21m
15 kts
41
57
79
102
136
181
227
306
30 kts
163
222
318
408
544
726
907
1,225
42 kts
327
445
635
816
1,089
1,452
1,814
2,449
60 kts
653
889
1,270
1,633
2,177
2,903
3,629
4,899

They also state the following:  A “Lunch Hook” should be able to hold your boat in a 15 kn breeze. A main, or “Working Anchor” should hold up to 30 knots of wind. A “Storm Anchor” is for winds up to 42 knots.


And now let's put to work.  


 BANJER'S GROUND TACKLE ESTIMATION (Several Methods)

1.- Following different Rules and methods.

1.1.- Spain/CE
First let's use one of the possible recomended tables to choose an anchor and it's rode that are available around there.  In Spain we have a compulsory regulation for the recreative market, based in CE's rules & regulations, as follows:

Anchor and Rode chooser, under the Spanish Rules & Regulations
Boat hull length             Anchor weight                    Chain diameter (*)            Rope diameter (nylon)
Anchor weight is supposed for what Spanish authorities assume as to being high holding power anchors
(CQR, Delta, Bruce, etc., and the like).
Chain shall be at least equal to one boat length long, and total rode at least 5 boat lengths long.

(*) Galvanized steel, under EN 24565

So, allowing for some margin, let's say that for a 36 footer, like Banjers, we should use, as a minimum, a 20 kg high holding power anchor, with 12 m of  8 mm chain and 48 m of 12 mm nylon rope. From here you can go up to the sizes your experience (or fear!) dictates.


1.2.- USA
Now the recomendations from the ABYC (American Boat and Yacht Council). The table express the recommended holding power in pounds. From the pages of BoatUS, where you'll find more useful info about anchoring.

Boat Dimensions Horizontal Load (lbs.)
Length
Beam (Power)
Beam (Sail )
Lunch Hook
Working Anchor
Storm Anchor
10’
5’
4’
40
160
320
15’
6’
5’
60
250
500
20’
8’
7’
90
360
720
25’
9’
8’
125
490
980
30'
11'
9'
175
700
1,400
35'
13'
10'
225
900
1,800
40'
14'
11'
300
1,200
2,400
50'
16'
13'
400
1,600
3,200
60'
18'
15'
500
2,000
4,000

So, for our beloved Banjers, we shoud use something slightly bigger than found in the bolded line. Let's say:

Lunch Hook: 240 lbs (109 kgf);  Working anchor: 960 lbs (436 kgf); Storm Anchor: 1920 lbs (871 kgf)

Comparing this with the upper Bob Smith's analysis, where 1520 lbs were calculated for a 63 knots wind, indicates the ABYC seems to be somewhat conservative, as I've also read about at some cruising forums. But, at sea,  to be conservative increases your security and, on the other hand, I'm not so sure about Bob's data interpretation, as well as not knowing the wind force used by ABYC for Storm conditions.

On the rode side, Boat US recommends a lenght of 300' (91.4m) of 3-strand 1/2" (12.7 mm) Nylon, and 3/8" (9,5 mm) chain for a 35 footer, so in our case we can asume:

Rode:  Length, roughly 100 m; 13 mm Nylon rope; 9.8 mm chain

Chapman’s suggests using one half foot of chain for each foot of boat length, so in our case 4.75 m. But Earl Hinz, a former aeronautical engineer and inveterate Pacific Ocean sailor, in his work The Complete Book of Anchoring and Mooring, says “the chain lead should weigh at least as much as the anchor whose weight it is supplementing”. From his experience, he has determined that the length of the chain lead has nothing to do with the depth of the water or the length of the boat. His suggested formulae:

Minimum Chain Length = (Anchor weight in lbs * Anchor material factor) / Unit weight of chain in lbs/ft

Anchor material factor = 1 for steel and 1.6 for aluminium

For a 20 kg (43 lbs) steel anchor and a 8 mm chain (weighing 1.15 lbs per foot), as those recommended in the Spanish regulation, we should use 11.4 m (37.4 feet) of chain, more or less one boat length for Banjers.  The Spanish chain's length reccomendation seems to be quite adequate, according to this, but asks for a too short total rode length, according to Boat US. I believe Spanish authorities are taking in account the almost universal recommendation of letting out a rode length of about 5 times the depth, for "standard" anchoring.

1.3.- The traditional method.
Among the cruising community there is a simple rule many folks used to talk about: "You need a main anchor weighing 1 pound per waterline foot". So, for Banjers with a waterline length of about 31.17 feet, we shoud go for a 32 lbs anchor. I find this number not really enough at all for Banjers, as my own 'working tackle' with a 33 lbs Admiralty anchor has proven inadequate on sandy bottoms with strong winds in the range of Force 6. Confirming this, numbers obtained with the calculator mentioned in point 4, suggest that my working tackle will not withstand winds in excess of 20 knots (Force 5).


1.4.- Calculations using Al's Anchoring Tackle Calculator.
We enter Al's calculator with the following data, taken from my own good old MARIE:
11.13 m boat length, 10 mm chain diameter, 50 m available chain length, 63 knots wind speed, 800 daN selected rode tension, 6.5 m total depth (5 water + 1.5 freeboard), Medium seabed holding.  (Note: 1 daN = 10 N = 10/9.81 kgf = 1.02 kgf)

Results:
a) All chain rode: 3.5º rode angulation at anchor. 8:1 scope, 21 kg minimum anchor weight.
b) Mixed rode for a 0º angulation:  20 kg anchor,  50 m chain,  22 m nylon rope.

Notes:
Static mode tension for 63 knots appears at the calculator to be 650 daN (663kgf), which coincides pretty well with the upper Bob Smyths analysis (689 kgf), although data there is said to include waves effect (?). Dynamic overtension with mixed rode goes in Al's calculator up to 1430 daN, and with all chain rode staggers to an incredible 3251 daN.

The data taken from MARIE, with a 20 kg CQR, 50 m chain, and the adition of 22 m of nylon rope, as well as using the 800 kgf rode tension, indicates that the boat is able to withstand winds of 47 knots, the upper limit of a Force 9, with a 0º rode angulation at the anchor, which is more than enough for my usual sailings.

If we calculate with 1430 daN, we arrive to the needing of a 30 kg anchor and 58 m rope, in adition to the 50 m chain, for a 0º setting.

Note: Author says he consider CQR, Danforth, Bruce, Britany, etc.,   "classic" anchors, and Spade, Brake, Bügel, Delta, etc., "high-holding" ones, for which a 30% reduction in weight can be considered.


1.5.- Calculations based on Banjers wind profile and Phil Dunhulty's Nomogram.
I have been doing some preliminary work with this Nomogram, but numbers for Banjers move in the limits of the curves and I am not sure about anchors efficiency index. Not enough trustable information about this indexes, in my opinion, is posted at Dunhulty's web pages. But making efficiency index equal to 40,  which seems to be a fair index for high holding power anchors, I arrive to an anchor weight of 22 kg for a 63 knots wind, so not so far away from other methods. But lower efficiency indexes call for heavier anchors. I've written a letter to Dunhulty asking for help. Let's wait.

On 09/02/05 I received this kind e-mail from Phil Dunhulty:

"Dear Guillermo
Thank you for your interest in the anchor efficiency paper
1. The answer to your first question is yes, certainly you may extend the graphics.
2. The different anchor efficiencies are fairly well explained in the paper. See Figure 16 and 17 and 18
These tables cover most of the anchors commonly in use with their respective indices
What more can I tell you.
Regards
Phil Dulhunty"

Figure 17, from Phil's pages:
Type
Test Results Efficiency Index (Holding Power to weight ratio)
Average
Admiralty Pattern
5, 7, 14
8
Bruce
16, 11, 9, 24, 22, 17, 25, 39, 30
21
CQR
36, 9, 12, 40, 26, 70, 12
30
Danforth High Tensile
34
34
Danforth Standard
17, 38, 34, 20
27
Flook
45, 55, 27
42

When I read Phil's article I asumed these data were not good enough to use them in the calculations, I recognize. I thought they were only indicative. I find dispersion of values too big and probably they are not comparable. I think it's risky to say, i.e., that 30 is a mean value for CQR anchors, when dispersion of values goes from 9 to 70 (!). And if we have to asume this kind of enormous variation, How can we asume 34 is a trustable mean value for Danforth High Tensile's?

Well, but using anyhow these data, and assuming for a 45 lbs (21 kg) CQR anchor an efficiency index of 30, we come to the conclusion that it's holding power, as per the nomogram, should be around 500 kg in sand/mud, which is not enough to withstand the Force 11 winds we are working with. We should go for a bigger one or either use some other anchor with a higher efficiency index, but which one is that one? We cannot say it from Phil's table, except for Danforth High Tensile and Flook, so, as I told before, those data are not trustable enough, in my opinion.


1.6 What for Hurricane conditions?
We'll now use William's van Dorn's formula, developed for oceanographic vessels in storm conditions, to estimate the forces acting on a ground tackle subject to an anchorage subject to severe wind and sea conditions:

Rode Forde = 0.20* Wind speed^2*Displ^(2/3)  (lbs)

Using a 75 knots wind (well into Force 12) and a  Banjers' displacement of 13.7 tonnes (30870 lbs), as per hydrostatic curves, we come to an staggering:

Banjers Rode Tension = 6545 lbs (2,97 tonnes or 3026 daN!!!)

This is really a huge tension, much more than that those obtained from Bob Smyth's analisis or the ABYC rules (1920 lbs).

Using Al's calculator for a 11 m boat in 10 m depth, good seabed holding, 1.5 m bow and a ground tackle using a mixed rode of 15 m, 10 mm chain and nylon, to obtain a dinamic overtension (due to wind and waves) of 3026 daN for mixed rodes, we need to introduce in the calculator a wind of 92 knots instead of the 75 considered in Van Dorn's calculations. So, we can realize the difference among both methods. Van Dorn takes into accoun the Displacement and Al's calculator takes Length, which may be the cause of the discrepancy.

With the preceding data, following Al's calculator to handle a 92 knots wind, (Assuming a rode angulation at the anchor of 8º), we need an anchor of 35 kg, as well as 70 m nylon rope in adition to the 15 m chain , to get a 6:1 scope.

 Following Van Dorn's tables (From the pages of C&C Yachts):
"...However William van Dorn in "Oceanography and Seamanship"; Dodd, Mead (1974),  presents a graph based on calculations for anchoring oceanographic vessels in storm conditions (?). It suggests that the optimum chain/nylon combination for anchoring vessels < 50ft. in 30 ft. of water under storm conditions is a 20% chain, 80% nylon rode with an overall scope of 6:1. Assuming that the boat's bow chock is 6 feet above the water and that the waves are 4 feet (8 feet peak to trough = 2.4 m) this works out to a 240 foot total rode comprised of 48 feet of chain (14.6 m) and 192 feet (58.5 m) of nylon. Clearly these are extreme conditions. In shallower water the rode could be reduced proportionately. However, the length of chain required approximates one boat length and a good working rule for a combined rode is a boat length of chain plus whatever nylon is required to give a 6:1 scope. In shallower water, the scope should be increased, within swing limitations, to 7:1 to permit the bow to lift more easily to the choppy waves near the shore".



1.7.- 2005 Germanischer Lloyd's Rules
Now let's have a look on what a reputable Classification Society states for Yachts and Boats under 24 m length.
From the 2005 edition of their Rules & Guidelines, Pat 3, Special Craft, Section 3, Yatchs &  Boats under 24 m, Letter G, Anchoring, Towing and Warping Gear, we calculate the following for Banjers:

Numeral     Z = 0.6*L*B*H1 + A  =  53.14 m3
Being:   
L=(Lh+Lwl)/2 = 10.41m  
B = maximum hull breath = 3.48 m
H1 = draft, corrected = 2.3m  
A = 0.5* Wheelhouse volume = 3.12 m3 (over deck, roughly)

With this numeral, and a Displacement of 12 tonnes, we enter the different tables and formulas and we obtain (Minimum values for all around sailing):

Main anchor weight:   21 kg  (For what they nominate as "high holding power" anchors: Bruce, CQR, Danforth, D'Honne, Heuss, Pool & Kaczireck)
Secondary anchor weight : 18 kg. (You must carry both)
Length of chain line: 32.5 m (round bar steel chain, DIN 766)  (for every anchor)
Anchor cable nominal thickness:  8 mm
Towing line length:   50 m
Towing line nominal diameter: 22 mm   (3-strand hawser-lay nylon rope, DIN 83330)
Warping ropes: 2 of 15.6 m and 2 of 10.4 m, 18 mm nominal diameter, same rope as before.


In adition, GL states the follwing:

- The weight of Main and Secondary anchors may vary in +/- 7% if the combined weight is no less than the sum of the stipulated weights. (This sum for high holding anchors is, in our case, 39 kg, which approximates the 35 kg obtained before for 92 knots winds, using Al's calculator)
- Both anchors may be on chains or on lines with chain outboard shot.
- Main anchor weight may be reduced 25%, to be used in inland waterways where strong currents and high seas can be excluded, in our case 16 kg. May be substituted by an Stock anchor of 1.33 the weight of the main anchor,  in this case 21 kg again.
- The chain may be substituted by 49 m of 22 mm three branded nylon rope plus 6 m of 8 mm outboard shot chain, shackled to the anchor. Rope line must have a spliced-in thimble at one end.
- Anchor chains and chain outboard shots must have reinforced links at the ends.
- A swivel is to be provided between anchor and cable.
- The chain has to be made fast to the boat in a quick release safe operating manner, with fastening strength being no less than 15% but no more than 30%, of the normal breaking load of the chain.

    And gives the following caring recommendations for synthetic ropes:

- Stowage below deck once at sea (because of solar radiation)
- Do not stow near heating appliances.
- From time to time inspect them carefully for external and internal defects.
- Replace defective thimbles. Splice-in loose thimbles afresh and seize-in firmly.


My interpretation on this two anchors scheme is that we could use a working tackle with a 18 kg anchor and 49 m of  22 mm 3-strand nylon rope, plus 6 m of  8mm chain, for good weather anchoring, ready to be made fast in line to the main 21 kg anchor with the 32.5 m of 8 mm all chain rode, when strong winds, even up to hurricane forces, are expected. Something to ask Germanischer Lloyd (??).

Both anchors should be fast setting ones.

With the working tackle as said before, we could handle 40 knots winds (The top of a Force 8) in a 10 m depth anchorage, which is good enough for most ocasions. The extra diameter of the nylon rope of the working tackle is needed to be able to withstand the force in a hurricane, when deploying the two anchors, working both on this rope. Well, but I realize we, most of mortals, do not face hurricanes often, so probably we could use a little bit of more chain, let's say 12 m, and a lighter rope, of let's say 16 mm, (much more handable but still with more than enough resistance) for the "normal conditions". When we expect things may deteriorate to really heavy conditions, then we should add the main anchor and substitute the 16 mm rope for a 22 mm one.

To allow for corrosion, etc, I'd go for an all around 10 mm chain, instead of the 8 mm recommended.



2.- What do manufacturers recommend for a 36 feet heavy boat?
Here you have the information from some well known anchor manufacturers. Some of them enter with weight of the boat, rather than length.

   
 


Bruce: Storm, 13kg; Working 6.5 kg; Rope: 15 mm; Chain: 9 mm; Minimum chain length: 6.5 m; Anchor shakle: Pin diameter: 10,5 mm, Body diameter: 9 mm.
Spade: Model 100, 20 kg (steel). For boats with LOA < 50', Disp < 12 tonnes.
CQR: Maximum recommended size (Drop forged): 16 kg / 35 lb
Delta: Maximum recommended size (Galvanized): 16 kg / 35 lb
Danforth (20 knots winds): Standard model, 16 lbs / 7.3 kg; Chain minimum length: 4' (1.22m); Chain diameter: 3/16" ( 5mm aprox)
Flook: 10 kg (22 lbs); 3 strand Nylon rode, 13 mm. Shackle size: 12 mm.
Fortress (30 knots winds): FX 16, 4.5 kg / 10 lbs. Nylon rope, 13 mm; 4 m chain, 8 mm; Shackle, 8 mm.
Max: Max 17 (Pivoting, 50 pounds; Rigid 57 pounds)
Buegel (Bügel): HS Steel, 24 kg; 10 mm chain (For boats from 10 to 15 tonnes)
Luke (fisherman): Storm anchor, 72 lbs (35.5 kg)  (They recommend 2 lbs per WL foot)

Their commercial sites, some of them with interesting info about anchoring and anchor tests.


Notes:

1.- Some of those recommendations seem to be quite low for serious cruising, from my point of view, as we've seen before.

2.- Interesting to find that Danforth and Fortress, the two anchors more prone not to reset after breaking away on sandy bottoms (as per the tests upper mentioned in this article), are the only ones to advert the wind velocity in their anchor chooser (20 & 30 knots, respectively), just telling you have to be cautious for higher wind velocities.

 (02.07.05)  MORE ANCHORS IN THE MARKET:
(Click on images to access their web sites)

SARCA
MANSON SUPREME
ROCNA
BULWAGGA
OCEANE

The recommendations from these manufacturers for a Banjer like sized boat are:

Sarca:  Sarca Anchor Nº 7, Galvanized (25 kg / 55 lbs). Leader chain, 13 m of 12 mm. Stainless shackle 12 mm.
Manson Supreme: No recommendations available at the web site.
Rocna: Rocna 20 (20 kg / 44lbs / 1174 cm2 blade area) (Size kindly confirmed by Craig Smith, of ROCNA Anchors)
Bulwagga: 44 lb ( 20 kg). Because of length it could be 27 lbs (12.3 kg), but they advertise going one size bigger if the boat is a heavy weight (And Banjers are!)
Oceane: Oceane 16, 16 kg / 35 lbs

Interesting to find that the manufactures of all these "new breed - high holding" anchors, except Oceane's, recommend a weight in the range of of 20-25 kg (44-55 lbs), also in line with Spade's and Buegel's. "Older" plough/claw type anchors like Bruce, Delta, CQR and the like, recommend (see upwards) weights in the range of 16 kg (35 lbs) or less, which seems to be not enough at all. So the "high-tech" guys, who talk about special surfaces, chisel blade tips, balanced weight and the like, finally go for a much more conservative weight recommendation than manufacturers of the less sofisticated anchors (!!!). I like this approach, meaning to me that although a good design is important to the performance of an anchor, weight is also a fundamental parameter not to forget for an all around one.


New kid on the block (Nov 2006)
HydroBubble
This anchor has had very good results in Sail Magazine 2006 Anchors Test, with an extraordinary holding power.
From SAIL magazine: "Quick sets and multiple 5,000 pound pulls at 5:1 scope proved it worked beautifully everytime"
Its setting characteristics are not based in weight (neither total or tip's), but in attaining always the right position because of the floatation bubble.
They reccommend their model Standard 45 for a Banjer like sized boat.


Phil Dunhulty's bottom/anchor table

Approximate Relative Holding power of equal weight anchors in different Types of holding ground
Grapnel
Admiralty
Bruce
Plow CQR
Danforth
Stockless
Flook
Mud
2
3
7
8
7
6
9
Sand
3
5
7
7
8
6
9
Gravel
5
6
7
6
6
6
7
Clay
6
6
7
6
5
4
6
Weed
7
8
4
4
4
3
5
Rock
10
8
2
2
2
1
3

(Ratings Out Of Ten)

No anchor is designed to hold well in all kind of bottoms.
For serious cruising you should carry two or three types aboard.


3.- My practical suggested method to test your anchor weight and type: 'Bollard Pull' test.
Here you have something interesting to do this season!
As we found before, a Force 11 wind will impose the rode with a force more or less equal to the Bollard Pull of a 27" propeller in a Banjer mounting Perkins 4236, as a rough approximation.
So, you could take your beloved Banjer to a convenient and isolated location, with a  3/5 mts depth firm clay (**), mud or sand bottom , with no boats around, in a calm day. You should look for a bottom as horizontal as possible, with no weed. Don't test in very soft mud or clay, as most anchors don't hold well (Unless your anchor is specifically designed for this job, as the Fortress at 45º), neither in a hard clay, dense sand, weed or gravel/rocky bottoms, as your anchor may not set, penetrate adequately or bending at the flukes.
Firmly dig your main anchor by means of short bursts of power (you may visual check it with the help of a tender in clear waters). Let out  25/35 mts of a 13 mm+  nylon rope plus 10 mm chain (at least one boat length of chain), making it strong to both rear cleats of the Banjer by means of an 'Y' strong rope connection. Slowly open throttle up to 2250 rpm for Perkins 4236 or around 1700 rpm for Perkins 6354 (If you go all the way up with this engine, you'll be exercing a pull in excess of 900 kg, which makes a more demanding test) Then slowly veer the boat 30º to each side. If the anchor holds, or moves but not breaks out, this could be one to take with you for an extended voyage. If it doesn't hold, or fails to reset, you'd better use it only under trustable conditions, as a Lunch Hook or a Working Anchor, depending on its performance.
Finally, test a 180º veer, not under full revs but easing power, gently turning in a wide circle and then slowly opening throttle when the rode is under slight tension again. Watch for the anchor dragging and reset. If it resets and holds to full throttle again, that should be really THE anchor! (For that bottom type)
Try several locations and tests on the same kind of bottom, if possible, to find mean conditions.

I kindly ask members to perform this test with their own Banjers, whenever possible, and let me know the details and results.

(**) Firm clay may be defined as the one on where your thumb will penetrate several inches with moderate effort.


4.- Rode: Chain,  Rope, Shackles and the like, from other sources.

Chain

The following are typical maximum working loads for common chain sizes. Working loads are assumed to be at maximum a 25% of breaking load. Numbers are approximate and may vary from different manufacturers. Equivalencies among metric and imperial units are approximate. Numbers in bold highlight what should be the minimum choice for Banjers.

Standard Long Link
Size (in)
Size (mm)
Working Load (lb)  
Working Load (kg)
Weight lb/ft
Weight kg/m
1/4"
6
1250
567
0.638
0.949
5/16"
8
1900
862
1.006
1.497
3/8"
10
 2650
1202
1.456
2.167

BBB Short Link
Size (in)
Size (mm)
Working Load (lb)  
Working Load (kg)
Weight lb/ft
Weight kg/m
1/4"
6
1250
567
0.72
1.071
5/16"
8
1900
862
1.108
1.649
3/8"
10
2650
1202
1.639
2.439

BBB short link or "calibrated" chain is required for use with anchor windlasses with chain gypsies.
It is important to match the chain and gypsy.


Rope
Nylon double braid or 3-strand rope should be the material of choice for anchor rodes. Braid is more susceptible to chafe than 3-strand, but coils better in the anchor locker and resists much higher loads. On the other hand 3-strand stretches more than the double braid and has better chafing-resistance properties. You may also use an 8-strand rope ("square" rope), but although with good chafing-resistance and working load properties, elasticity is poorer than 3-strand..
Numbers in bold highlight again what should be used for Banjers.

DOUBLE BRAID
Size (in)    
Size (mm)    
Breaking
Strength (lb)
Breaking
Strength (kg)
Working (lb)
Working (kg)
3/8"
10
 4800
2086
 1200
544
7/16"
11
6400
3084
1600
726
1/2"
13
8400
3810
2100
953
9/16"
14
11400
5171
2850
1293
5/8"
16
15400
6985
3850
1746

3-STRAND
Size (in)    
Size (mm)    
Breaking
Strength (lb)
Breaking
Strength (kg)
Working (lb)
Working (kg)
3/8"
10
3850
1746
 965
438
7/16"
11
1/2"
13
5265  
2388
1315
596
9/16"
14
5/8"
16
9100
4128
2275
1032


Shakle, Chain connecting links, Swivels, Anchor connectors, etc.

- For the shakle, recommendations are to use one size bigger than chain. So, if you go for a 10 mm chain, you should use a 12 mm shackle. Use drop forged, deep galvanized, load rated models. A 3/8" one will have a WL of 1 Ton, while a 7/16" one will go up to 1.5 Tons.

 How to do a warp to chain splice: Visit this Bluemoment page

- You should be careful with chain connecting links as they may be weak. Check their breaking strength. If in doubt, it's easier and simpler to use a proper shakle when gathering lengths of chain is required. Always respect the one size bigger rule. Never use "quick link" type shackles, as they are not designed for this job.

- Be careful also with swivels design and breaking load. Get sure they resist as much as the chain, at least. They really do not work properly under high loads, but will take turns out of the chain in most normal situations.

-  The same about stainless steel anchor connectors. They are nice looking and easy the passage of the anchor connection through the bow roller, but they tend to be weak in real life, many times with a breaking load being a fraction of that of the chain. Check it.


Chafing gear

Nylon will chafe, so you'll need to make good chafing gear. You may use a combination of heater hose, head hose, and fire hose about two feet long, as used by Jim Hughes on board his 50' Irish Mist, to protect a pair of snubbers used in between the rode and the boat, to absorb the chafe specially in storm conditions. You shoud never trust, for serious anchoring,  a rope rode working on the bow roller. If you have an all chain rode, use 13+ mm  3-strand snubbers secured to the rode by means of a rolling hitch or chain hook, lead them through the fairleads protected by the chafing gear, and make them fast to bollards or strong cleats.
Although original Banjer's windlasses are strong stuff, dont let the chain or rope working on them. Again: Use the snubbers. This will also take away the irritating noise of rode's chain against the bowsprit's chain. In fair weather I'd use only one snubber, leaving the use of two for storm conditions (In this case with rolling hitchs, not chain hooks).


 5.- Contributions by manufacturers.

If you're a manufacturer and want to add your contribution, please send it to me. I'll gladly post it here. You may do it by e-mailing me to g.gefaell<at>mundo-r<dot>com
Thanks in advance.


29.06.05 Contribution from ALAIN POIRAUD, creator of SPADE and OCEANE anchors

In principle, a good anchor must first and foremost hold, and ideally increase its holding power as forces incur heavier loads on the vessel... but in order to hold, an anchor must first deeply penetrate and set in the various types of seafloors. There are two types of setting: static and dynamic.
- Static Setting: Almost always followed by dynamic setting, this setting is typical for cargo ships, where the anchor, from several hundred to several tons of pounds, sinks into the seafloor from its sheer weight alone. No extensive research has been carried out regarding effective setting for these circumstances. In terms of small craft navigation, we can find a similar static setting with the plow anchor, which they don’t manufacture under 15 pounds, simply because anything lighter could not function. Anchors which are not sufficiently heavy may only offer cursory holding in more compact or weedy seafloors, but they might be very effective in soft mud.
- Dynamic Setting: The traction of the rode ought to force the anchor to pierce and bury in the seafloor. Although its own weight may facilitate setting (static), lightweight anchors will also set; it suffices that the anchor tip encounters a sand ripple, or a soft area to pierce, followed by the traction which drives the the anchor into a set position. On compact or weedy seafloors, anchors tend to skim the seafloor for some distance before taking hold. To ensure a speedy setting in virtually all types of seafloors, there are a certain number of physical characteristics to respect: Regardless of the tool, depending on the substance, two parameters ensure good setting: - The proper setting angle and - The highest amount of pressure possible. The optimal setting angle adapted for anchoring is the “wood chisel.”
- Spatula:  Plow anchors, once resting on a hard surface, assume a “spatula” angle with respect to the seafloor. Once the tip encounters a softer spot, it embeds by measure of its own weight to its upper apex, thereby assuming the “chisel” angle, which allows the anchor to completely embed. As previously mentioned, on a compact or weedy seafloor, the plow remains in its “spatula” angle, without setting.
- Scraper Angle: Anchors such as the old FOBs, with a bulky hind portion, tend to do a “handstand,” alighting on their flukes. At this point the flukes meet the seafloor almost perpendicularly, raking the surface without setting.
- Chisel Angle: Three principle examples of this are the Bruce anchor, the German “Bügel” anchor and the SPADE. All three approach the seafloor at an angle superior to 90 °, up to 120 °. These anchors have the reputation for rapidly setting in a majority of seafloors.
- Razor Blade Angle: This angle, superior to 150°, is typical of plate or articulating anchors. They necessitate contact with a sand ripple or soft area for their fluketips to pierce the seafloor surface; they then assume the chisel angle and set. On compact or weedy seafloors, these anchors shave the bottom without taking hold.
- Setting Pressure: Pressure is defined as force divided by surface area. Here, we have two variables: force (daN or Lbs) and surface area (mm² or sq inches). The force must be as high as possible and the surface as small as possible to maximize the pressure. A number of anchors have sharpened setting edges, as do the Fortress, FOB THP, the Bügel or the Spade. The distribution of weight in the fluke tip makes sense in anchor design as it facilitates setting. We can see a great disparity amongst fluke ballasting in various anchors: The fluketips of flat anchors and the CQR comprise between 12 and 16 % of the total weight of the anchor, while the ballasted tip of the Delta contains 28% of its total weight. - The... SPADE anchor... 47% of its total weight in its point. We can see that an anchor will tend to set more easily in the seafloor when it launches with the appropriate penetration angle coupled with the maximum pressure on its fluke tip.

Alain Poiraud's "Hylas" web site: www.hylas.ws

03.10.2005 Contribution from Craig Smyth, of Rocna Anchors

Hello Guillermo,
Given our conversation a few months ago, I thought you may be interested in this diagram we created:
http://www.rocna.com/images/remote/rocna_setting_forces_diagram.gif
Just a diagram illustrating the relative differences between tip-weight and setting forces. There is a great deal of confusion about the concept of "tip-weight", in part due to some manufacturers who maintain that a large amount of tip-weight is required to properly set an anchor. We feel obliged to point out that while some tip-weight is important, it does not need to be all that high.
You are welcome to use this graphic on your website.
Regards,
Craig Smith
Rocna Anchors
www.rocna.com


Read also this article from Peter Smiths, the creator of the Rocna anchor:
http://www.bluemoment.com/newanchors.html

13.11.06 Contribution from ALAIN POIRAUD, creator of SPADE and OCEANE anchors
Hi Guillermo,
Just for your information, I just discover the following web page made by one distributor of the Spade anchor..

http://www.bluewatersupplies.com/new_gen_anchors.htm

Good reading
Alain


April 18, 2007.  New contribution from Craig Smith (Rocna anchors)
Hi Guillermo,
I just took a look over your webpage on Anchoring once more, and thought I could contribute some more material for you.
- The SAIL and Yachting Monthly testing, which I think you are aware of, we host on our website (see "independent reviews"). You may like to link to.
http://www.rocna.com/press/press_0610_wm_sail_testing.pdf
...................
- An article published in the New Zealand Coastguard 2007 Handbook about anchoring: www.rocna.com/boat-anchors/anchoring-in-2007.html
- (New generation anchors explained): http://www.rocna.com/boat-anchors/new-gen-boat-anchors-explained.html
..................
Regards,
Craig


6.- Anchoring Forums & Reports

You can get most interesting user's info about anchors and their performance from real life experience, at these threads from some cruising
Forums:
- Best Anchor - From Seven Seas Cruising Association's pages
- Bruce vs CQR - Also from Seven Seas
- Anchoring - From Lattitudes & Attitudes
- An Anchoring Perspective - From SailboatOwners.com

And also valuable opinions from independent experts-
Reports
- Anchors aweigh (by Greg Jones)


7.- Books
A selection of books on anchoring (Links to some webplaces where to buy them. This is only a facility for BMC members and friends. BMC does not have commercial interests with the linked sites, nor endorses them).

- The Complete Book of Anchoring and Mooring by Earl R. Hinz, Richard R. Rhodes (Illustrator)
- The Complete Anchoring Handbook, by Alain Poiraud, engineer and inventor of the Spade anchor.


8.- For the time being: My own case study:
Now, what do I carry in my own Banjer, good old MARIE? The following:

One 45 lbs (20.4 kg) CQR with 50 m, 10 mm galvanized steel chain, for all around anchoring. I always sleep on this one, after checking for a proper holding and releasing five times the highest tide's depth, even in good weather and shelterd waters. I have not really tested it under strong gale forces, but only under lower gale scale forces (Forces 8-9). I've checked this anchor does not set well in weed bottoms
One 45 lbs CQR with 100 m 14 mm rope, as a secondary, stern and back-up anchor.
One 33 lbs (15 kg) Fisherman style anchor, with 12 m galvanized steel 8 mm chain and 40 m, 13 mm double braid nylon rope. I use it as a working anchor for good weather, low depth, day anchoring; either in sand, mud, weed, gravel or rocky bottoms. Not really trustable with Force 6 gusts on sandy bottoms. I extensively use it in Galicia's summer time, as it is easily and quickly brought back aboard by hand only, even if well digged in sand/mud. Very useful with weed, rocks and gravel bottoms, always using the compulsory buoy/retrieval line. But you have to be very careful about not dropping chain/rope -or veering around- over it, as it gets entangled very easily.

What do I miss, after all this reading and fussing?
Well, today, September 09.2008, I think I'd need to add 30 m of 14 mm nylon rope to the main ground tackle, to be able to withstand the worst of the winds expected in my area, sailing season and sailing behaviour, let's say if I get caught anchored in a Galician beach summer's night anchorage when a sudden SW front arrives with gusts reaching almost Force 10 (Most unprobable!).

If I were to go globetrotting, then I'd go for a higher holding power, quicker setting and strong anchor mounted on 70 m of 14 mm double braid nylon rope in adition to the 50 m chain. I'd also carry an spare full ground tackle similar to the main one, a high holding power flat anchor for soft muddy bottoms, as well my present light tackle with the dismountable fisherman's hook.

Now I'd love to hear from the readers' experience. I'll post at 'Contributions from readers' down here all of them, except those disrespecting or agreding others.


 9.- Contributions from readers

September 16, 2008
A contribution on anchoring from friend Dave Herndon:
Guillermo,
Your new page on Anchoring and Anchors has some great information.
A few years ago, I switched from a 35 lb CQR to a much smaller 17 lb Bulwagga for the main anchor on my Fisher motorsailer. The Bulwagga not only holds as well as the larger CQR, but works well in all the bottoms (mud, sand, oyster shell, and grass) found in the Chesapeake Bay area. It also fits well in a standard Danforth bow holder. The anchor grabs instantly with a strong hold every time I use it in all bottoms. I recommend any boater desiring a new anchor to consider a Bulwagga. To me it has more holdpower than any other anchor of similar weight.
Dave
David H Herndon
Owner, Wayward Wind (1978 Fisher 25)