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Go Back   SailNet Community > On Board > Gear & Maintenance
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  #1  
Old 06-24-2011
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General anchor ???

Am I wrong or is "Much Bigger" better ?? My biggest worry in the past was always dragging while sleeping. So wouldn't way over sized be better ??? ( except the weight of course ) I do understand the importance of chain also. Thanks in advance for any ideas or input.
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Old 06-24-2011
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If all you care about is setting and not dragging, then, all else being equal, bigger is better. If you care about actually using your anchor, then there are practical limits.

What sort of gadgetry have you got on your boat? If you don't have an electrical windlass, then how deep is the water you're anchoring in?
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Old 06-24-2011
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In my experience scope is more important than anchor size. I always shoot for 7:1 with chain/rope and 5:1 (or more) on all chain. I've never drug anchor and have anchored 200 times or so in the northwest and canada where there is much current, wind and extreme tidal movement.

Anchoring is an art, but the basics are thus:

1: An adequately sized anchor of a good brand. (no clones, no copies)

2: Adequate scope. 7:1 chain/rope or 5:1 all chain as a minimum. (Don't forget to calculate scope from the top of the anchor roller at high tide and take into account that your depth sounder may be located a few feet under the water. This extra calculation really can make all the difference, especially in shallow anchorages.

3: Set your anchor by backing up on it aggressively. If you don't back up on your anchor, do don't know if it's holding and will hold. It could just be sitting there in soft mud that won't hold, or tangled up in a ball. People are often very timid backing up to set their anchor. I can't figure why. When the wind picks up in the middle of the night I don't ever say "Boy am I glad I didn't back up harder to set the anchor deeper and test the set!". 1/2-2/3 throttle for 10-20 seconds is usually enough.

There's more to anchoring, but follow these three steps and you'll be fine.

And no, there's no such thing as too big.




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Old 06-24-2011
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The anchor above looks sufficient !!!! Thanks for the detailed info. I've been in typically shallow water, hard bottom & grassy areas..( Florida Keys type )
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Old 07-13-2011
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This brings up an interesting point. My wife and I were in the BVI's for the past 2 weeks on a Jeanneau 40.3 (chartered from a 2nd tier company), and we dragged twice during squalls. Both times the anchor was set with about 7:1 scope on an all-chain rode in about 8-10 ft of water doing nearly exactly as described above-- drop anchor via windlass, throttle back in reverse at about 2/3 power for about 10 seconds (which was repeated a second time)- boat did not budge while setting, then we just waited and watched for a couple of hours to be sure we were stationary by checking landmarks. The second dragging was scary- my wife and I were off the boat, leaving one friend alone (he slept in late). We walked around the western point of Anegada, snooped around the salt ponds, then started walking back along the beach and noticed a squall moving in quickly from the east. We hot-footed it along the beach back toward the dinghy, motored on over and found our buddy on the bow, and a stranger (nice guy from a neighboring boat) at the helm. While dragging, the boat had pitched 270 degrees clockwise, wrapping the rode around the keel with the anchor snared on the mooring just downwind from us and gently "bumped" (no damage) the 50 ft catamaran tied there. The volunteer skipper had our motor in reverse at about 1/3rd throttle keeping the boat snared in place between the two moored catamarans when I relieved him. We released the anchor rode (knowing we could easily dive for it later when things calmed down) then went about finding a free mooring ball. Right after I set the anchor (the day before) I dove down to check placement, and it was firmly buried in sand the way you'd expect- I believe it was a 25 or 30 lb cqr (no hinge in the shank), but this thing was oriented plow point down, both flukes up and completely buried in soft sand/grass about an inch below the surface of the seabed. The only thing visible was the shank, which is how I found it at the end of the chain. I couldn't imagine a better anchor setting, which leaves me to believe that maybe the anchor size wasn't suitable for this size boat. I'm very new at this, so I could use a little advice... Is there a guide somewhere that suggests proper anchors for different size boats? I know there is for different anchoring media, but haven't seen anything suggested for boat length.

Ray

Last edited by Irunbird; 07-13-2011 at 09:01 PM.
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Old 07-13-2011
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A 40' boat with a 25# CQR (Let alone CQR copy) is a bit light.
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Old 07-13-2011
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Only time I ever had problems with my old CQR (copy or not, I don't recall) was in soft sand. Didn't matter how much chain I put down or much I tried to make sure the thing was properly set as soon as the breeze piped up from onshore , away we would go.

It was in as an attempt to overcome this that we went Rocna.
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Old 07-13-2011
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Quote:
Originally Posted by MedSailor View Post
.....People are often very timid backing up to set their anchor. I can't figure why. When the wind picks up in the middle of the night I don't ever say "Boy am I glad I didn't back up harder to set the anchor deeper and test the set!". 1/2-2/3 throttle for 10-20 seconds is usually enough..........
I power back against the anchor at near idle speed. I watch the SOG on the chart plotter increase (usually to about 1 knot) stabilize, then eventually drop quickly to zero. The anchor must be set more than superficially to hold the boat to zero. I will grant that idling a 100 hp diesel may be pulling a bit harder than some. I'm not sure I see the value of powering harder. If a wind pushes harder, it will just continue to dig like the heavy power setting. If you swing, any anchor is going to unset and have to reset itself with no power. Whether it will or not, doesn't seem like it will be influenced by the initial set.
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Old 07-14-2011
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One needs to really SET an anchor at way more than idle speed. See below from a post Maine Sail made on our C34 Forum.

In order to answer the OP's original question, have a look at the ANCHOR SYSTEM sizing tables here:

Ground Tackle & Anchor System Sizing TABLES

Then size appropriately for YOUR use.

*******************************
*******************************

Last summer on a friends boat he left me at the helm while he went to drop his CQR. I backed down, like I always do, gradually increasing to 80% throttle and the anchor dragged!

Here's how the conversation went "Geez that's never happened before","Really? Lets try it again",.

On the second attempt it had an initial bite (starting to burry) but when I applied power it broke free. "Your giving it to much throttle and ripping it out of the bottom", "it's an anchor!", "let me try", "ok".

So I now go up to let the anchor down & he puts the boat in reverse gets it moving and then puts it in neutral and we get an initial bite. "There see it's set", "No it's just starting to dig in it now needs to be set", "It's always held me before", "Have you ever experienced a 30 knot blow on the hook?", "No" "Well a 30 knot blow on your boat is the equivalent of roughly 900 pounds of pull on the anchor did you know that?", "No", "Did you know that the motor on this boat can barely re-produce 350 pounds of pull wide open?" "No", "Well let's let it set your way and in a couple of hours we'll simulate 20 knots of wind with the motor and see and happens", "You're on". You can probably guess what happened. Because we never properly set the anchor it dragged! We did get it to set that day using a 10:1 scope then shortening to 5:1. My friend could not beleive that the CQR could hold his boat using 80% throttle and was totally surprised by it! Scary I know.... From my experience I find a CQR likes a minimum of a 7:1 to set but it sometimes prefers more..

He now understands that an anchor should hold your boat at wide open in reverse without moving. This is a guy who has been sailing for 25 years and admittedly dragged "perhaps 20 times but never with my CQR"! Once is to much! It's imperative the anchor gets "set" properly. Yes the CQR sets better in soft bottoms than in sand but not all boaters are lucky enough to always drop the hook in a soft bottom. So if you're in a hard bottom make sure to get it set. The CQR will set well but it may take more than one attempt. Don't ever be fooled by the "initial bite". With a CQR this is a situation where the anchor is laying on it's side with the tip just starting to dig in. Like the picture at the beginning of Sail Magazines article. If you stop there on any sort of wind or current shift the anchor will twist out. A CQR needs to be vertical and buried to the shank or it's not properly set. If it's properly buried it can sometimes survive a 180 shift without "breaking free". I suggest some of you begin diving on your anchors in a shallow spot to see what's going on down there I think you'd be surprised...
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Old 07-14-2011
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Quote:
Originally Posted by Minnewaska View Post
I power back against the anchor at near idle speed. I watch the SOG on the chart plotter increase (usually to about 1 knot) stabilize, then eventually drop quickly to zero. The anchor must be set more than superficially to hold the boat to zero. I will grant that idling a 100 hp diesel may be pulling a bit harder than some. I'm not sure I see the value of powering harder. If a wind pushes harder, it will just continue to dig like the heavy power setting. If you swing, any anchor is going to unset and have to reset itself with no power. Whether it will or not, doesn't seem like it will be influenced by the initial set.
There's a bit of difference between an inertia set, as you're doing, and a set from a dead stop where you throttle up to cruise RPM or more in an attempt to set the anchor. In the quote above from Stu we were starting from an anchor rode already played out and from a dead stop there was not any inertia of a moving mass to really "yank" on the anchor and it was more gradual, like slowly tightening the line for a water skier, because that is how I have found CQR's set better.

If I had done an inertia set it is more like starting with slack in the water ski like and ripping the guys arms out by the shoulder sockets cause your going 12 knots by the time the skiers rope slack is gone. Some anchors, like the newer generation anchors, actually seem to do really ,really well with inertia sets. Our Spade, Manson Supreme and Rocna all do tremendously well with inertia sets. For an old gen anchor the Bruce does okay...

I do it both ways and find both equally effective, with a good anchor. With a poor setting anchor an inertia set can often rip the anchor out before it actually gets deep enough to continue burying so a slow ramp up to 80% is what I generally prefer with say a CQR or Delta.

Before bed I always do a throttle up set but often while anchoring it is an inertia set where the anchor has to stop the entire moving energy of our 19,000 + pounds at 1-3 knots.....

Your inertia set is likely applying much more than throttling up to 80% of WOT from a dead stop. Our boat can do about 500-600 pounds of load at 80% of WOT with a 44HP diesel and fixed three blade. I would guess the spike on an inertia set with our boat breaks 1000 pounds. I guess I have another experiment to do.....
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Last edited by Maine Sail; 07-14-2011 at 02:51 PM.
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