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Old 04-03-2013, 07:18   #211
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Re: Anchors, Bigger is better?

Only read the first few pages and the last few! - so not sure if raised already.......

.......the seabed is usually waterlogged (in suspension?), and how much ./ deep likely to do with the type of bottom - therefore my (non-scientific!) thinking is that a bit of weight to settle in / through won't do any harm, whether it does any good is I guess the purpose of this thread!

FWIW, heard a story (in real life) recently about someone who discovered a bottom in which no anchor could hold, no matter how "new", how big or clever. Fella was the back of Mont St Michel (Northern France) and couldn't get his anchor to set....local came over and mentioned that he was trying to anchor on a carpark. made of tarmac!.....he knew it was tidal but hadn't realised that included a carpark!.....ended up anchoring nearby, at low water discovered was in the middle of the run from an outfall - from the smell was for most of Northern France!......all told that kinda answered the puzzle as to why there was plenty of space to drop the hook.
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Old 04-03-2013, 07:30   #212
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Re: Anchors, Bigger is better?

jonjo -

i'm merely relating my real world experience. let me relate the real world experience of one who has been out there for the past ten years.

bill dietrich of 'magnolia' has a blog he's been maintaining since around 2000, and i've been reading it since about then - the only sailing blog i follow. he has a first generation gulfstar 44 with a pilothouse. he's done the east coast usa and for the past seven years or so has been through the bahamas, up and down the west indies, and is currently just north of grenada. as a full time liveaboard he's been through all kinds of weather and anchoring conditions.

his anchoring gear? main anchor, cqr 45 on 120 feet of chain. second anchor, 40lb danforth on 120 feet of chain. third anchor, cqr 35, not sure about the rode.

i'm certain that if he was concerned about his anchors he would spend whatever it takes to buy the best. but his experiences tell him that his anchor choice works best for him, just as my experiences tell me my combination works for me.....
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Old 04-03-2013, 07:38   #213
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Re: Anchors, Bigger is better?

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in the bahamas i had problems with the cqr even penetrating the heavy clay bottoms;
Where in the Bahamas do you find a clay bottom? I can't recall such a thing, though I am sure it exists over there. However, 90%+ of the anchorages are pure sand, and most of them are deep softish sand that provide perfect holding. There are some that are extra hard and it is hard to get the anchor to penetrate, but still sand. I have anchored all over most of the central and northern Bahamas with a CQR and I don't ever recall dragging except while trying to set the anchor in Black Sound where the bottom is near impenetrable weed. Still, I eventually got my CQR down through it and it held in some big blows.
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Old 04-03-2013, 12:27   #214
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Re: Anchors, Bigger is better?

kettlewell -

might be a description problem. when i pull my manson the blade is nearly always full of a clay-like substance. might just be the heavy sand minus some of the water that has dripped off it. since you've been there too i think you recognize what i'm talking about, although my chosen word may not be exact. i usually knocked it off with my windlass handle.

i don't anchor in black sound; i take a mooring ball for $10 a day so we get showers and head and dinghy dock and a ten minute walk to town (or five minutes to pineapples). white sound is another story.

my cqr worked pretty well in north and central bahamas, although i would often dive on it after an experience off chub cay where the bottom was hard coral and sand. had to move the anchor around by hand to get it in between some coral. didn't sleep too well that night, chub cay being a wide open 'anchorage'.
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Old 04-03-2013, 12:33   #215
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Re: Anchors, Bigger is better?

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Originally Posted by David_Old_Jersey View Post
ended up anchoring nearby, at low water discovered was in the middle of the run from an outfall - from the smell was for most of Northern France!......all told that kinda answered the puzzle as to why there was plenty of space to drop the hook.
Which begs the question of which anchor holds best in sewage sludge.
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Old 04-03-2013, 12:35   #216
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Re: Anchors, Bigger is better?

I guess I would call it more of a muddy sand. There is somewhat more organic material mixed in with the sand in the Abacos, with more pure sand further south. Still, I don't recall having any major issues getting a 35-lb CQR to set there, which I had on my 32-foot cat. I suspect the Manson will do better with its sharp point, which will aid penetration, that's for sure. I have heard of people who took a file to the point on the CQR to make it very sharp--and rusty too.
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Old 04-03-2013, 13:15   #217
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Re: Anchors, Bigger is better?

There's been some talk above about the Bahamas and finding sand that is deep enough over a hard layer for good holding. I've found it very useful to look through the clear water for the holes formed by marine worms that are commonly seen in the sands that are at least 18" deep and never on the hard bottom. These holes give the bottom the appearance of a pancake that is ready to flip. Often there will be places where you can find areas with worms in a patchwork pattern among less desirable places. Anchor on the worms!
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Old 04-03-2013, 14:24   #218
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Re: Anchors, Bigger is better?

Is it any wonder that environmentalists and greens are having bays and estuaries closed to anchoring that have been used for decades, sometimes centuries (at least in the UK, and decades in younger Australia) when yachts take a pleasure and pride in lifting seabed. I'm not sure we do that much harm but others see it differently. Yachtsmen are a terrible focus group, we engender little sympathy, greens and environmentalists are flavour of the decade, or half century - for votes. Taking pleasure and pride from damaging seabeds is not useful. We think we are environmentally friendly, black water tanks, use of the wind - but think not once about destroying seabeds - odd really. In fact lift an anchor full of mud and we rub our hands with joy - point to our 'green' neighbours as to how great our anchor is - get real. Its unnecessary, if it clogs, its dangerous.

In Oz there was some talk of banning use of Concave anchors in some geographic areas - until they quickly realised it would be difficult to enforce. The option seems to be banning all anchoring, altogether. Its happened here in Oz, anchor bans to protect the seabed, its happened in the UK.
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Old 04-03-2013, 14:29   #219
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Re: Anchors, Bigger is better?

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Originally Posted by CaptForce View Post
Anchor on the worms!
Might those "worms" be garden eels?

I believe the variety found in the Bajamas is Heteroconger longissimus.
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Old 04-03-2013, 15:18   #220
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Re: Anchors, Bigger is better?

Quote:
Originally Posted by JonJo View Post
Is it any wonder that environmentalists and greens are having bays and estuaries closed to anchoring that have been used for decades, sometimes centuries (at least in the UK, and decades in younger Australia) when yachts take a pleasure and pride in lifting seabed. I'm not sure we do that much harm but others see it differently. Yachtsmen are a terrible focus group, we engender little sympathy, greens and environmentalists are flavour of the decade, or half century - for votes. Taking pleasure and pride from damaging seabeds is not useful. We think we are environmentally friendly, black water tanks, use of the wind - but think not once about destroying seabeds - odd really. In fact lift an anchor full of mud and we rub our hands with joy - point to our 'green' neighbours as to how great our anchor is - get real. Its unnecessary, if it clogs, its dangerous.

In Oz there was some talk of banning use of Concave anchors in some geographic areas - until they quickly realised it would be difficult to enforce. The option seems to be banning all anchoring, altogether. Its happened here in Oz, anchor bans to protect the seabed, its happened in the UK.
Egads, you REALLY hate concave anchors... Now they are distroying the world! Though i have a feeling you wrote this to satisfy the devilish side in you, i cant help but take the bait

Just breathing, we disrupt the environment. Anchoring on corals heads, I thought that is why anchoring got(is) such a bad rap..? But I have been out of the loop a bit. Care to give source specific to concave anchor ban? And I would think dragging anchors cause more disruption, and imagine double the disruption with two anchors

I really think you have great insight, though a bit rabid at times, you have pulled more depth out of a topic than I thought possible.

Cheers,
Erika
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Old 04-03-2013, 15:40   #221
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Re: Anchors, Bigger is better?

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Might those "worms" be garden eels?

I believe the variety found in the Bajamas is Heteroconger longissimus.
Excellent thought, but the garden eels are sparse and the marine worms are ubiquitous Polychaetes. The Brown Garden Eels that you refer to are also more common deeper water than the Polychaetes that are found in depths to 20 feet.
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Old 04-03-2013, 15:47   #222
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Re: Anchors, Bigger is better?

Houston we have a problem here.

We all have to take moorings.

STOP ANCHORING.

I repeat

STOP ANCHORING
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Old 04-03-2013, 17:10   #223
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Re: Anchors, Bigger is better?

Have just finished my unified theory of anchoring... phew, now my head hurts, and I am sure most of you bellys might be aching with derision (specially if you come from an engineering background). Anyway for what it's worth (it's free) you can find it here

Anyway the nuts and bolts of it is a poor attempt to come up with a few anchor size ratios to judge the size of anchor and compare between different boats, much like SA/disp ratios, and Disp/length.

Displacement to Anchor weight ratio = Disp (kg)/Anchor weight (kg)
I get values from 350-500, lower reflecting a bigger anchor.

Displacement to Anchor Area = Displacement (tonnes)/(Anchor fluke area (cm^2)/1000)^(3/2)
I get values ranging from 4.9-11 for sensible sized anchors . Lower reflects a bigger anchor.

Windage to anchor area ratio = windage (m^2) / (Anchor fluke area (cm^2)/1000)
This seems to give a value between 11-15, with lower numbers for bigger anchors

Windage to anchor circumference = windage (m^2)/(circumference (m))^2
This gives me about 5.4-6 with lower numbers being better.


This spreadsheet seems to point to me why the larger boats seem to be using much bigger anchor than the manufacturers charts show they need. Most of the anchor charts don't seem to reflect the way windage and displacement scale vs anchor area. I am sure the anchor makers have done much more research than I have so I don't discount there graphs, It just makes it hard to compare if your anchor is bigger or smaller relative to your windage and weight than other totally different boats.

I am interested if this approach is worth pursuing, maybe a database of workable anchor ratios might help sort out what works and what doesn't. The hard part would be comming up with a simple way to assess windage.

If anyone is interested in the spreadsheet I can email it to you or dump it someplace online. My blogspot site doesn't seem to allow any files like that.
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Old 04-03-2013, 17:31   #224
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Re: Anchors, Bigger is better?

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Originally Posted by Cotemar View Post
Houston we have a problem here.

We all have to take moorings.

STOP ANCHORING.

I repeat

STOP ANCHORING
That's one way to take the sting out of these anchoring threads.

Now back to those polychaetes....
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Old 04-03-2013, 19:46   #225
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Re: Anchors, Bigger is better?

Quote:
Originally Posted by Ocean Girl View Post
Egads, you REALLY hate concave anchors... Now they are distroying the world! Though i have a feeling you wrote this to satisfy the devilish side in you, i cant help but take the bait

Just breathing, we disrupt the environment. Anchoring on corals heads, I thought that is why anchoring got(is) such a bad rap..? But I have been out of the loop a bit. Care to give source specific to concave anchor ban? And I would think dragging anchors cause more disruption, and imagine double the disruption with two anchors

I really think you have great insight, though a bit rabid at times, you have pulled more depth out of a topic than I thought possible.

Cheers,
Erika
Hi Erica,

I said it was considered to ban concave until it was realised it could not be enforced.

In Jervis Bay, Australia, there is an anchorage called 'The Hole in the Wall'. It has been used as an anchorage almost since the first Europeans arrived as a place of shelter from southerly storms. It appears in almost the earliest of Admiralty Pilots and is certainly well documented in one I hold dated 1970ish. Within the last 5 years, I do not recall when, anchoring has been banned in water shallower than 10m at low water (tides are only 2m) to protect the seagrass (I do not know the species). Huge swathes of the Barrier Reef now have blanket bans on anchoring. Huge stretches of New South Wales ocean coast, for example just north of Coffs Harbour have blanket bans on anchoring, and its not the coral they are protecting but common or garden seabed (though environmentalists would differ). I recall, do not know status but bays around Manly, Sydney have blanker anchoring bans or it is dicussed to impose them. I think Studland Bay comes to mind in the UK, but that's anecdotal - I'm not sure what is happening in the UK but a lot of people there are upset about blanket bans on anchoring.

I appreciate its not happening in your backyard, but it is happening here.

By the way, I do not hate concave anchors, I just hate concave anchors that destroy seabeds and might be dangerous. I'm not keen on people who make an asset out of lifting great chunks of seabed and providing ammunition to a vocal and powerful lobby. The Boss might work, do not know. Mantus might work, do not know. Spade is not a problem, carries little, in my experience no, mud. Sets as quick as you can blink, sets well, renowned holding capacity, fits virtually any bow roller. Highly commendable. Comes in 3 versions, a weight for every taste (less keen on stainless, bling under water does not seem all that useful. I'd like the Ultra, except its stainless and costs a King's ransom. So unlike some I'm not completely blinkered. But I do not blame you if you did not read every post to filter out my likes and dislikes

Really glad you enjoyed the thread - maybe we should have more
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