Anchoring 32' Sloop

[rgleason]

Ground Tackle Examples:

1. Mantus Chain Sizing Chart shows 1/4" HT G43 for 20-30' boat with 11,000 lbs. displacement.
2. Nova Scotia 35' Cruise Sailboat 14,000 lbs 9/16” nylon on primary anchor with 25’ of ¼” chain and 1/2" nylon on the back up.
3. mitiempo Canadian SailCraft CS27 6500lbs, Lewmar Pro 1000, self stowing chain under V berth (removed tank). all-chain 1/4" G43 x 225' (168 lbs) Rocna 15 (33lbs),
4. Don C L Columbia 29 MK1 28.5' LOA/ 22.5' LWL 8,400 lbs, No windlass. Hauling 80 lbs up from below and to the foredeck is a bit if a challenge. Danforth 20H + (2) 12Hb, 100' chain + 3-strand nylon typical depth 20-25' 5:1 100' chain + 25' nylon. Can shackle 45' chain + (2) 100' lengths of chain. Always anchors bow and stern. Snubber double wrap prusik loops of 3-strand nylon. 250' more chain stored over the keel for ballast for hurricane..
5. Don CL friend Luders 30, 9,900 lb Manual Windlass, 50'of 5/16" chain
6. Viking Iso Kalvo response Bristol 32' loa / 22lwl, 10,800 lbs, Viking 7, 200' 5/16" G43 chain, add snubber plate with long climbing ropes in hurricane conditions.
7. Shrew suggests: 150' x 1/4" g40 + 5/8" line + 22 - 25 lb anchor (Spade, Rocna, manson, etc)
8. Orion Jim Cape Dory 31 11,500 lbs Lofrans Royal manual windlass, which I rarely use. Spade 33# (2) Crosby 7/16” G-209A shackles + 110’ of Acco 5/16” G43 chain spliced to 115’ of New England Ropes 5/8” three strand nylon line. Kedge Mantus 25# anchor (2)Crosby 7/16” G-209A shackles to 20’ of Acco 5/16” G43 spliced to 175’ of New England Ropes 1/2” three strand nylon line. This combination has kept me safe from New England to Bermuda.
9. mlydon Allied Seawind 32' Ketch,14,900 lbs, windlass gypsy, 30' 5/16" chain + 300' 5/8" 8 plait. Originally had 210' chain, when removed bow came up 3".
10. Stu Jackson C34IA 12,000 lbs No windlass, 50' x 1/4" chain with 200' x 5/8" (oversized) 3 strand, depth 20-30'
11. Stu's friend C34 12,000lbs & Manta 40, 13,000 lbs Windlass Rocna 20kg of it with 100ft chain works great in 25-50' depth
12. Pete7 31' Moody 11,243 lb S-L Anchorman Manual Windlass, 45m x 8mm (147' x 5/16") chain plus 10m(33') of double braid rope, snubber 10m 3-strand 10mm with a chain hook half way between bow roller and the water so snubber is dry, runs back to the genoa winch. Simple and works. 12Kg Vulcan.
13. Mathias Wagner - in tight space, not optimal using his calculator, 44 metres (144') chain + “good” snubber, with anchor alarm on to act quickly, not to using best snubber/bridle, as the good one is easy to get off.
14. rslifkin Catalina 381 27,000 lbs. 5/16" G43 x 90' with 3900 lbs WLL (From ABYC Table a 55 knt wind will reach the WLL). Worries most about 5/8" 8 plait (11,000 lbs MBS, 2200 lbs WLL)
15. Apollo Hunter 37 17,800 lb 50' x 5/16 G4 chain & 200 ' 7/16 nylon 3 strand, 4 anchors, same rode on each: Vulcan 15 kg, Lewnar Claw 22#, Danforth 25#, Danforth 15#. A new generation anchor of 25-35 lbs would make it pretty bomb proof.
16. ScottMeilicke, 30,000lb Windlass, 250' chain + 150' Yalex, backuprode 60' chain + 300' Yalex never used, even in 100' depth 250' chain + 150' was ok, only used twice, with Yalex polyester, always skinny 3/8"-1/2" 3-strand nylon snubber with rolling hitches length dependent on situation (shock absorption, chafe protection, chain quieting) Likes the abrasion coating on Yalex.
17. David Mathis Wellcraft 43 5/16" G43 x 30' with 1/2" nylon double braid with Bruce 44 and Danforth 25 lb backup.
18. Boatman likes Liros Anchorplait 8-plait nylon, from JimmyGreen.com Bruce + 200ft chain and Fortress kedge: 50ft of chain + 150ft of multi-plait performed just fine with all that chain up forward..plus water tank.

[rgleason]

Nylon vs Polyester Anchor Rope
The Right Rode by Steve Dashew Polyester 8-plait improves strength and abrasion resistance. Cconservative selection same size as nylon (consider Windlass).
Polyester over Nylon Rode? (Cruiser Forum Thread) 8 and 12 plait polyester lines make great rodes, really flexible, and a good balance of stretch and strength. As a extra bonus, they are really easy to splice." In the Polyester over Nylon? thread Unity Post #14 has a good public spreadsheet and analysis. His Unity Post #17 gets even better and more detailed.
rslifkin: Depends polyester line. Tenex specifically, it stretches 2.3% at 20% of breaking load. 8 plait nylon is typically around 10% stretch at 20% load. And size for size, Tenex is stronger. So the effective stretch (at the same absolute load in pounds) is something like 1/6 of nylon, meaning you'd almost certainly need to use a snubber unless you have 200+ feet of the stuff deployed. ( So Polyester 8-Brait 5/8" x 200' x 2.3% stretch at 20% Breaking Load (of )5/8" = 4.6' stretch at

Post: How to scale the stretch to match the boat and swell & veer conditions

E-rigging Comparison See Rope Comparison at bottom of page

• Polyester strength is a little less than nylon, but it does not loose 15% when wet and does not absorb water.
• Polyester is a little less elastic than nylon,
• Polyester Elongation at Break 15-20% whereas nylon is 20-34%
• Polyester has better abrasion resistance than nylon.
• Polyester 8-plait anchor line would probably be very good with similar handling to nylon 8-plait.
• Strength Comparision: Double braided Polyester vs Nylon
  • 1/2" polyester 7425 lbs /5 = 1,485 lbs MLW vs nylon 7800 lbs x .85 (when wet) = 6,630 lbs wet /5 = 1326 lb MLW
  • 9/16" polyester 11250 lbs /5 = 2,250 lbs MLW vs nylon 12200 lbs x .85 (when wet)= 10,370 lbs wet /5 = 2074 lb MLW
  • 5/8" polyester 16000 lbs /5 = 3200 lbs MLW vs nylon 17350 lbs x .85 (when wet) = 14,750 lbs wet /5 = 2,950 lb MLW
  • Polyester is about 8-9% stronger than Nylon.

Polyester Rope and Stretch

Novablue 5/8" 12.6 lb/100') 16,100 lb Break Strength, 3220lbs MWL(5:1) Abrasion Resistant. Polyester double braid
Polytec-12 5/8" 13.1 lb/100' 15,100lbs Break Strength 3000lbs MWL(5:1) Polyester 12 strand
Blendtec 5/8" 20.2lb/100' 11,000 lbs Break Strength 2200 MWL(5:1) Polyester 12 strand
Yalex Polyester 12-plait

1/2" 8.4 lbs/100' 15,370 13,833 3,074 lbs MLW (5:1)
9/16" 10.3 lbs/100' 18,860 16,974 3,772 lbs MLW (5:1)
5/8" 11.6 lbs/100' 20,900 18,810 4,180 lbs MLW (5:1)

Sampson Tenex Polyester 12-plait

1/2" 8 lbs/100' average strength 12,500 lbs min.strength 11,300 lbs, 2,260 lbs MLW (5:1)
9/16" 10 lbs/100' average strength 14,400 min.strength 13,000 lbs, 2,600 lbs MLW (5:1)
5/8" 12 lbs/100' average strength 18,500 min.strength 16,700 lbs, 3,340 lbs MLW (5:1)
3/4" 17.2 lbs/100' average strength 24,400 min.strength 22,000 lbs, 4,400 lbs MLW (5:1)

Polyester Break Strength - Elastic Elongation

10% 1.4% 16700 lbs x .10 break strength for 5/8" = At 1,670 lb, 100' 5/8" x 1.4% elongation = 1.4 '/100' of stretch
20% 2.3% 16700 lbs x .20 break strength for 5/8" = At 3340 lbs, 100' 5/8" x 2.3% elongation = 2.3'/100' of stretch
30% 3.00% 16700 lbs x .30 break strength for 5/8" = At 5010 lb, 100' 5/8" x 3.0% elongation = 3.0'/100' of stretch

Nylon Break Strength - Elastic Elongation

10% break strength 3% Elongation 12,840lb x .10 break strength for 5/8 = At 1,2840 lb, 100' 5/8" x 3% elongation = 3'/100' of stretch
20% break strength 5.3% Elongation 12,840lb x .20 break strength for 5/8 = At 2,5680 lb, 100' 5/8" x 5.3% elongation = 5.3'/100' of stretch
30% break strength 7.7% Elongation 12,840lb x .30 break strength for 5/8 = At 3,850 lb, 100' 5/8" x 7.7% elongation = 7.7 '/100' of stretch

Summary

For 5/8" Line at 20% of the breaking strength,

• Polyester - 2.3'/100'ft
• Nylon - 5.3'/100'ft

Polyester line is approximately 8-9% stronger than nylon.

If you chose polyester 8-brait anchor line, a 1/2" nylon snubber or bridle will be needed, depending on size and length of chain to provide (adjusted for the force (lbs) needed as calculated by Mathias Wagner's calculator).

• 40-50 knots - 8'-11' of stretch
• 30-40 knots - 7-8' of stretch
• 20-30 knots - 4-7' of stretch
• 0-20 knots - 1-3" of stretch

For chain-rope rodes, using the strength of a polyester anchor line, and controlling stretch with an "excellent" nylon snubber for wave surges and veer, may be a good way to respond, however the standard approach is to use a nylon rode with its built in stretch of approximately 5.3'/100' for 5/8" line (often without a snuber).

[Barkingmad]

You can laugh if you want but I don't drag!
CS33 with a lewmar windlass. 75' 5/16 g43 chain, 250' 5/8 3 strand nylon.
55 pound lewmar delta! (primary anchor)
Anchored everywhere from Lk. Ontario to the South Shore of Nova Scotia.
I can pull it by hand easily if I have to.
And yes it does fit on the roller if I pull the shank a little bit to starboard to clear the drum on the furler.

Got that anchor for free, always laughed at it calling it the hurricane anchor, until I started using it.....
I am considering adding a Fortress.
Back up is a 35# CQR, lets just say once it sets it will hold. How many tries it will take to get it to set is another story. I wouldn't want to sleep through a tide change with that one either.

[rgleason]

Calculators
Anchor Chain Calculator-online version – Mathais Wagner (excellent)
Snubber Size Calculator -Snubberhead (excellent)
Anchor Chain Length Calculator- Liveaboard
Anchor line diameter calculator- Liveaboard
Snubber Size and Diameter Calculator -Fryes Formula- Livaboard
Fryes Snubber Calc- Practical Sailing

[rgleason]

I liked Steve's latest testing s/v Panope 45lb Anchor. Sandy Mud Winch Testing. Video # 130 .

He tested big anchors with short chain 12'x 5/16" chain + 3/8" Dyneema 5:1 scope (depth:30" scope:150")

Rocna 44 - Anchor Force 660 lbs / about 30 knots on Panope 34' 6-7 tons
Force on anchor goes up by the square of the wind.
Heavier 3/8" BB all-chain 3:1 rode improved performance to about 900 lbs.

Bruce 44 - Anchor Force 700 lbs
Earlier test with 3/8 BB all-chain 3:1 improved performance to 750 lbs.

Viking 20 (51 lbs) - Anchor Force 5300 lbs - amazing.
Vulcan 20 (47 lbs) - Anchor Force 5300 lbs - incredible.

My interest was in the effectiveness of the short, relatively light chain with rope rode which is how we've been anchoring for 30 years with a lighter Bruce 22 lbs. I am starting to realize that our gear is perhaps a little light for our boat, but these tests were encouraging.

Hopefuly I will have some additional information about Mathias AnchorChainCalculator next, showing how to calculate for a chain-rope rode. I am hoping he will review my figures first.

[rgleason]

Here is Mathias Wagner's strong argument, calculations and illustrations for using all chain. Mathematic approach to anchoring scope Post #360

Partial quote:

The maximum of m g /2 Y (L - Y) is reached for a fixed chain length at L/Y = 2, i.e. when the chain has twice the water depth and the scope is 2. Then the chain works best in this scenario.

However for more safety 3:1 or larger scope for all-chain is used.

Then:

Therefore, in practice, one will choose a much larger chain length to water depth ratio - the scope L/Y.

But as I said, the chain does not like shallow water. There, a very elastic snubber / bridle must take over and absorb all load peaks.

For anchoring with a short chain and long rope rode in shallower water a good elastic snubber and an elastic rope anchor rode is necessary for leveling out peak (yanking) loads and veer loads on the anchor, because there is little anchor catenary.

However is there a limit to the amount of stretch that should be provided? Should we be considering an 8-plait polyester anchor line which is more abrasion resistant, about 1/2 the stretch and is not subject to 15% reduction in strength when wet like nylon? Then rely on a relatively long snubber or bridle to adjust for and provide the necessary stretch and elongation needed for wave impact and veer?

[rgleason]

Calculation of a rope-chain rode

using AnchorChainCalculator, Mathias advised:

The iterative calculation of a mixed chain rope rode I would do as follows:

1. Select the chain thickness of the chain you are using.
2. Use the MAX field to enter the amount of chain you actually have.
3. Fill in all vessel details and wind strength.
4. Play around with the water depth until the tool tells you the angle at the anchor shaft is zero.
5. Now use a calculator to calculate the amount of rope required to get up to your bow roller.
6. To do this, use the bow angle alpha as given by the tool, and the sum of height of bow roller over water line and remaining water depth to the loose chain end.
7. Use sin(alpha) = remaining height / length of rope, for length of rope = remaining height / sin(alpha)
8. Length of the rope is known (first approximation) and bow load as provided by the tool.
9. From your rope data sheet find what percentage stretch under the working load.
10. Then use the rule of three to work out the stretch for a rope of this length at 8 Beaufort, or 40.2 kn of wind.
11. Use this distance for the tool's snubber "custom value" in Basic Mode or Expert Mode.
12. It is fiddly.
13. To make matters worse, we have not handled Velocity at anchor which is more complicated to include and would require more iterations until all is consistent.

I have not heard back from Mathias, so he is probably sailing. After playing around with his purchased Android App "AnchorChainCalculator" a lot, trying light chain that is shorter and similar to the 10'x3/8" chain + Rope 8:1 scope we've used for years, to understand the dynamics more completely:

Vessel weight 11500 lbs
Vessel length 32 feet monomed
Chain size 1/4" Max 40.0 feet
Wind strength 26.0 knots
Anchor depth 0.0 + 2.0 feet <--- Yes, this adjusted to get anchor angle=0 under the conditions...
Seabed angle 0.0
Swell energy or Vessel velocity
43.1 Joule 0.24 knots <-- somehow adjust for gusts and waves in harbor with medium fetch.
Snubber Excellent
Calculate
Bow swinging circle 39.9 feet
Anchor load 230.0 lbf Angle 0.0 degrees
Bow load 231.1 lbf Angle 5.7 degrees
Snubber stretch 3.10 feet 90.8%
(Screenshot attached below)

Calculate Rope Rode using Bow Angle and depth at 26 kn Wind

• Depth = bow roller down to the end of the chain = 17' (3' bow + 14' depth to chain)
• Sin(bow angle) = remaining height / length of rope
• Rope rode length = remaining height / sin(5.7degrees) = 17 feet / sin(5.7 degrees)
• Length of rope = 17 / .099319 = 171 feet of rope anchor line required

Calculate Snubber and Snubber Load (actually the long Nylon Anchor Rode)
This is just preparatory to learn about strech and loads, and get a sense of how it works.

1. Using the attached spreadsheet "AnchorRope.xlsx, with Bow load=231 lbs and Rope Rode length = 171 feet
2. Spec data sheet for Nova-8 Nylon, it appears that with a bow load of 231 lbs
3. 5/8" dia x 171' would stretch about one foot and 1/2" x 171' would stretch about 1.5 feet.
4. Bow load = 231 lbs
5. Find rope data sheet "percentage stretch" under the working load (WL).
6. 1/2" Nylon 3-strand 7500 lb x .10% = 750 lb 3% stretch
7. 5/8" Nylon 8-plait = 2,950 lb MLW (after loss of 15% when wet) (3% elongation)
8. 5/8" Polyester 8-plait = 3200 lbs MLW x .10% (1.4% elongation)

Another trial
Use the rule of three to find the stretch (ft) of a snubber rope (of a given length) at 8 Beaufort (40.2 kn) of wind.
Use this snubber value in the custom value in Basic Mode, or in Expert Mode.

Vessel weight 11500 lbs
Vessel length 32 feet monomed
Chain size 1/4" Max 40.0 feet
Wind strength 40.2 knots Beaufort 8
Anchor depth 0.0 + 1.5 feet
Seabed angle 0.0
Swell energy or Vessel velocity
248.5 Joule 0.6 knots <--- close to .7 because it is high winds and bigger waves & surge?
Snubber Excellent
Calculate
Bow swinging circle 40.0 feet
Anchor load 560.5 lbf Angle 1.0 degrees
Bow load 561.3 lbf Angle 3.3 degrees
Snubber stretch 7.43 feet 99.9%
(Screenshot attached below)

Calculate Rope Rode using Bow Angle and depth at 40.2 kn Wind
Depth = bow roller down to the end of the chain = 17' (3' bow + 14' depth to chain)
Rope rode length = remaining height / sin(3.3 degrees) = 17 feet / sin(3.3 degrees)
length of rope = 17 / .057564 = 295 feet of rope anchor line required to keep the anchor angle at 1 degree.

1. From the attached spreadsheet 5/8" nylon x 295' with Bow load of 561lbs stretches 4 feet.
2. While the 1/2" nylon x 295' with the same bow load stretches 5.8 feet.
3. Neither of these lines are loaded close to 20% of breaking strength, at 4.37% and 6.35%

Using Rule of three at 8 Beaufort

Now to do this with the anchor chain calculator using rule of three...

1. Using NER Premium 3 strand 1/2" 7,500 lb x 20% break strength= WL 1500 at 12% Stretch
2. Total stretch at WL of 1500 lbs = 295ft x .12 = 35 ft of stretch
3. Use the app to calc the Anchor Load with vesssel displacement 11500 chain 1/4" max 0 feet, wind 40.2kn, Anchor Depth 0 Vessel Velocity 0
4. Anchor load AL is 395.7 lbf
5. WS * AL/WL = (Working Stretch) (Anchor Load/ Working Load)
6. 35.4ft * 395.7lbs/1500 lbs = 35.4ft * .2638' = 9.33 ft of stretch
7. Now I need to use the 9.33 ft of stretch at Beaufort 8 40.2kn wind in the calculator
8. So I entered 9.33ft under Custom Beaufort 8 40.2kn
9. Then did two calcs with the calculator:
10. Depth of 10 ft and no max anchor chain, need 117.1 ft of 1/4" chain.
11. Depth of 10 ft max anchor chain 40 ft, anchor load and snubber length increase, anchor angle 12.9 degrees.
12. (See two attached screenshots.) These calcs are assuming a separate snubber, but I am using the nylon anchor rode.

In this last example I used 1/4"chain x 40' + 250' of 9/16" novabraid nova-8 nylon (normally we have had at the most 160' of 3-strand). I am not sure if we've been in 40 knot wind for that long, but I can recall several nights and one huge fast moving storm where I am pretty sure we hit 30-35 knots. Also we've been able to find protected anchorage places when needed in our 30 years of sailing. In the event of worse weather (climate is getting worse), I suppose we would also put our or 22 lb danforth and 200' + 10' 3/8" chain.

I think having these parameters in Mathias calculator would be great, and save those using chain-rope a lot of trouble:

1. how long the rope is, or can be
2. stretch in % at a certain working load.

BTW

Bruce still makes anchors, but they are huge. This design looks interesting with a double pointed tip and bolt on dual shank, but the smallest is 500kg, too big for s/v Panope to test... I believe there yet another "new generation" ahead of us.

[rgleason]

Here are screenshots of the calcs done in AnchorChainCalculator
My spreadsheet will not upload. but I will add .pdf to it which has to be removed.

[rgleason]

Thinking about this further:

testing s/v Panope
45lb Anchor. Sandy Mud Winch Testing. Video # 130 .

He tested big anchors with short chain 12'x 5/16" chain + 3/8" Dyneema 5:1 scope (depth:30' scope:150')

The Viking 20 (51 lbs) and Vulcan 20 (47 lbs) anchors were winched up to 5000 lbs. load until breakout. The Rocna 20 (44 lbs) was winched up to about 700 lbs.

It is clear that these loads pulled all of the catenary out of the chain and the rode was very tight. Calculations show that the Anchor Angle = 7.8 degrees.

Granted, that these loads are unusual, and the sandy mud was good holding, but it is very interesting that the anchor angle went up to 7.8 degrees before pulling out at such high loads.

In our case with a Bruce 22lb and generally letting out 10'x3/8" chain + 100'-120' of rode, in 16'-18' of water, (approx 8:1) when the anchor load increases to stretch the rode straight, I calculate the Anchor Angle as between 7.6 - 9.2 degrees. We have been in 30-35 knots of wind and the anchor performs well and generally does not pull out.

Using Alain Frysee's Dyn-Mix spreadsheet with the same basic conditions, this spreadsheet calculates "Angulation" as 12.3 degrees.

His sta-mix spreadsheet shows "Angulation as 4.9 degrees with similar conditions.

My conclusion is that it is certainly preferable to have the anchor angle = 0 degrees, but in our use, the anchor has been tensioned to at least 5 degrees and has held. Therefore provided we improve the anchor and rode gear, we should be able to continue using a mixed rope-anchor rode.

[Don C L]

I am trying to imagine the conditions where a 32 foot boat will exert 5000 lb of force! Will the cleat or capstan on that boat hold that? And 50lb anchor, is that necessary? By the time things get that hairy you'll probably be letting out more scope, no?

[rgleason]

Don, we aren't going to have a 50 lb anchor, I am considering 12kg anchors (26-27lb) as a second phase of the plan. The things I find most interesting about these tests is:
1. The short chain (12') and long rode 5:1 (150') in 30' depth and excellent holding.
2. The Anchor Angle = 7.8 degrees at the final breakout load of 5000 lbs.

We can certainly have this scope with 250' of nylon rode. While the breakout angle will be less in worse soils, it does inform me more about how necessary it really is to be at the optimal Anchor angle of 0 degrees!

In bad soils and anchorages and wind and wave conditions, it is best to try to keep your anchor angle at 0 degrees, but having anchor angles greater than that (within reason) does not necessarily mean that it will break out. We need to exercise common sense and judgement.

He did these tests with 12' of 5/16" chain, and I am considering 40' of 5/16" or 1/4", which would be better. Alain Fraysee shows that the place to put additional weight is at the bottom down near the anchor to help keep the anchor angle smaller, and considered a kedge, but determined that chain is better. The rope rode then provides the necessary elasticity.

I am also considering having 60' of 5/16" or 1/4" in a bag on top of the keel water tank, in the rare event that we need it.

[rslifkin]

Originally Posted by Don C L

I am trying to imagine the conditions where a 32 foot boat will exert 5000 lb of force! Will the cleat or capstan on that boat hold that? And 50lb anchor, is that necessary? By the time things get that hairy you'll probably be letting out more scope, no?

I highly doubt a 32 foot boat will ever apply that much force. But if the anchor can hold that much in a good bottom, that means you've got lots of margin for if the bottom is softer, or you want to use shorter scope to fit in somewhere tight (which will reduce holding power), etc. So you can handle a wider range of sub-optimal conditions before your holding power is reduced to "not enough".

[rgleason]

Right now I am considering these choices for chain:

*1/4" G43 x 40' = .73lb/ft x 40' = 29.2 lbs ($3/ft x 40' = $120)
*5/16" G43 x 28.3' = 1.03lb/ft x 28.3' = 29.2 lbs ($3.80 x 30' =$114)
3/8" G43 x 18' = 1.62 lbs/ft x 18' = 29 lbs ($4.89/ft x 18'= $88)
*will work with possible future windlass.

I like the cost of of 3/8" chain and the idea of keeping the weight at the bottom to improve anchor angles, but I think 5/16" chain offers the option of using it on a windlass in the future. I might just get 40' of it too.

rdlifkin, yes the loads won't get that high, but these were tests with 45 lb anchors and in the second phase we'll just have a 12kg or 27lb anchor (to replace our 22lb Bruce) so the comparable pullout loads would be certainly be less. Also s/v Panope did the tests in sandy mud bottom which is good holding....

[Pete7]

Originally Posted by Don C L

I am trying to imagine the conditions where a 32 foot boat will exert 5000 lb of force! Will the cleat or capstan on that boat hold that? And 50lb anchor, is that necessary? By the time things get that hairy you'll probably be letting out more scope, no?

I think Steve said that 30 ish foot yacht will have 500-600 kgs of force in winds approaching a TS. 5000lbs is nearly 2.5T in Kgs, that's half the weight of our yacht and likely to pull the two cleats clean out of the deck along with the top of the bow locker.

Just going back to one point raised earlier were it was mentioned that manual windlasses are slow. Yes the horizontal type are, but a our vertical one with a long winch handle can be spun quickly with one hand whilst I kneel on the deck. In calm conditions we don't need it. Add a knot or two of tide or a strong wind and everything changes, especially if you hook an anchor full of mud or weed which we have done.

[rgleason]

Pete7 Agreed. We don't need 20kg 45-51 lb anchors. I think for our boats 12kg is more than enough. The thing I found most interesting was bar tight pull out forces at 5:1 with 12' of 5/16" chain and mostly rope rode, for me, the most significant thing about these tests, was the anchor angles. I then realized that you can try for 0 degrees, but sometimes that is not going to be possible, and then it is a matter of considering all conditions and having good judgement. I realized that our Bruce has been holding at low anchor angles for years in up to 35 knots and with the exception of eel grass situations has not pulled out.

Recently, using Alain Fraysee's spreadsheets, I analyzed various short chain lengths and sizes and their effect on anchor angle, trying to optimize and reduce the angle as much as possible. For just a few pounds more of chain, I was able to make some significant improvements with 26'-30' of 5/16" (27-31 lbs) chain instead of the 3/8" x 15' (24 lbs) that is now all rusty). I was a little surprised about this because I thought that it would be better to have as much weight as possible down near the anchor.

Using his rodeanch spreadsheet, at 30 knots with a mixed chain-rope rode I get between 240-260 lbs static with dynamic overtension of 570 lbs in wind gusts), and at 40 knots it goes up to 462 lbs (1016 lbs dynamic).

In another of his spreadsheets static-mixed rode, I get slightly less tension, but this spreadsheet shows that at static tensions equivalent to 40 knots, a 15 lb kellet just shacked to the end of the 25' chain makes a big difference, basically pulling the anchor angle down to .2 degrees. Such a weight could easily be lashed or shackled to the chain end prior to a blow, and be easily pulled up together with the anchor.

Originally Posted by Pete7

I think Steve said that 30 ish foot yacht will have 500-600 kgs of force in winds approaching a TS. 5000lbs is nearly 2.5T in Kgs, that's half the weight of our yacht and likely to pull the two cleats clean out of the deck along with the top of the bow locker.

Just going back to one point raised earlier were it was mentioned that manual windlasses are slow. Yes the horizontal type are, but a our vertical one with a long winch handle can be spun quickly with one hand whilst I kneel on the deck. In calm conditions we don't need it. Add a knot or two of tide or a strong wind and everything changes, especially if you hook an anchor full of mud or weed which we have done.