Anchor choices

[kmacdonald]

Originally Posted by noelex 77

Yes, I agree if you do not have a windlass then reducing anchor and chain weight is critical. I have cruised for many years in smaller yachts without a windlass so I understand the issues.

However, it is important to realise the restrictions this sometimes imposes. That does not mean you cannot have great time, but if you have limited anchor size and chain length this places some extra constraints on where and/or what anchoring conditions can be safely utilised.

It is not sensible to impose these same limitations for boats that can manage heavier anchors with just the push of a button.

Great! I thought I was going to have to trade in the wife for a younger and stronger model along with the 15kg Rocna. What a relief for her.

[thomm225]

Originally Posted by spudsdailey

I have a 48 ft. Offshore. It came with a Bruce. I tried a Rocna but it would not fit properly. I eventually chose the Vulcan, made by Rocna. I have used it for a year, and it has never failed me. Fits just fine as well.

So what was wrong with the Bruce?

Did it not work for you? Or did you just want to buy a new anchor?

I believe they were used successfully for many years on cruising boats world wide.

I'm still enjoying the CQR that came with my boat.

I have a one off Bruce as backup, but haven't had to use it yet even in 30 knot onshore winds (when I was 70 yards off the beach) since thankfully the CQR held in the muddy bottom we have in this general area

[Lodesman]

For the OP - we've been very happy with our Rocna, but would in all likelihood have been just as happy with either of the others. We've never had an issue with it, but allegedly they have problems penetrating thick weed, whereas Spade and Mantus supposedly do better. None of them do as well in soft mud as a Fortress. So if your cruising ground favours a particular bottom that is a consideration. Rocna does have great fit guides and patterns, so you can always do a cardboard mock-up to ensure a proper fit. https://rocna.com/fitment-guide/

[Adelie]

Originally Posted by kmacdonald

Dont oversize. The manufacturer already did that for you.

Oversize it to the biggest you can handle.

Regardless of what the manufacturer has done for sizing, the anchor is usually the weakest link in the anchoring system. Unless you dive on the anchor in clear water so you can see all around, you will have minimal info about how the anchor is sitting, what it’s dug into or what is around it that will affect it during a current or wind shift. You can guess but not really know what the max expected wind will be overnight or until the next time you raise the anchor.

ABYC guidance for rode size is very conservative so there’s plenty extra there if you follow that.

[Adelie]

Originally Posted by noelex 77

Yes, I agree if you do not have a windlass then reducing anchor and chain weight is critical. I have cruised for many years in smaller yachts without a windlass so I understand the issues.
.....

If you need to reduce weight chain is the place to do it. In 100’ of water going down 1 size chain will from 5/16 to 1/4 will save you 37lb (32lb in water) in uphaul weight. That’s like down sizing you anchor 3 or 4 sizes.

That difference gets bigger as the desired chain size increases.

[Dockhead]

Originally Posted by Adelie

If you need to reduce weight chain is the place to do it. In 100’ of water going down 1 size chain will from 5/16 to 1/4 will save you 37lb (32lb in water) in uphaul weight. That’s like down sizing you anchor 3 or 4 sizes.

That difference gets bigger as the desired chain size increases.

That's Dashew's formula -- put the weight into the anchor and take it out of the chain if necessary.


However, I like the effect of catenary from heavy chain especially in deep water. I have 330kg (what is that, 726 pounds?) of 12mm chain, which dwarfs the weight of the 100 pound anchor, and as much as I would like to get some of that weight out of my bow, I just don't -- because it is so great to have in bad weather and deep water.


I guess if forced to choose one should follow Dashew's advice but best of all is to have BOTH large anchor -- the biggest you can realistically handle, as Dashew recommends -- AND heavy chain, in my opinion.



IIRC Dashew used 176 pound anchors on his Sundeers.

[Michael Cobbe]

Originally Posted by AlohaSpirit

I have selected three anchors a Spade, a Rocna , and Mantus. I am looking for your experience with those if any.

For better holding our rule was buy one size bigger than the one recommended for the yacht.

[Dockhead]

Originally Posted by Michael Cobbe

For better holding our rule was buy one size bigger than the one recommended for the yacht.

One size up is a good start, but two sizes up is better. As Steven Dashew said:


"[T]he anchor is not big enough until people begin to laugh at you. . . "
SetSail FPB » Blog Archive » More on Anchors and Sizing


The bigger the anchor, the better it sets. The bigger the anchor, the more margin of error you have in marginal holding, and the more flexibility you have to use short scope if you need to.


No one ever lay in his bunk at night at anchor with a gale howling thinking "I wish I had a smaller anchor".


The more experienced the sailor, the bigger -- and more worn! -- the anchor.

[Mike OReilly]

Originally Posted by Adelie

Oversize it to the biggest you can handle.

Regardless of what the manufacturer has done for sizing, the anchor is usually the weakest link in the anchoring system. Unless you dive on the anchor in clear water so you can see all around, you will have minimal info about how the anchor is sitting, what it’s dug into or what is around it that will affect it during a current or wind shift. You can guess but not really know what the max expected wind will be overnight or until the next time you raise the anchor.

ABYC guidance for rode size is very conservative so there’s plenty extra there if you follow that.

As far as the need to reduce weight, I'd too go with Dashew's formula (if that's what it is) and focus on chain weight if need be. But completely agree with DH; chain weight is also very important. Catenary, and/or simple frictional force, holds boats most of the time.

[Lodesman]

Originally Posted by Dockhead

No one ever lay in his bunk at night at anchor with a gale howling thinking "I wish I had a smaller anchor".

In those conditions it's doubtful they'd be thinking "I wish I had less chain", either.

[rslifkin]

For the catenary thing, if you either use a mixed rode (with a large length of chain) or use long, well sized snubbers, you can make up for a lot. The idea being that by the time you pull the chain tight, the snubber or line is already loaded enough to be stretching noticeably, so you get a smooth ride with the catenary absorbing light shocks and nicely transitioning to the line absorbing heavy ones.

The key is to make sure you have enough catenary to achieve this. Putting out more scope can help you achieve that, as it takes more force to get the chain tight at a lower angle where it's harder to lift it, even if you're not adding any more chain weight to the equation. Lighter chain can also let you carry more of it, allowing longer scope when swing room allows.

[Mike OReilly]

Originally Posted by rslifkin

...Lighter chain can also let you carry more of it, allowing longer scope when swing room allows.

That's a good point rslifkin. If a boat is hitting weight limits for its anchor gear, I'd consider going with lighter chain if that meant the difference between carrying adequate scope, or not.

[rslifkin]

Originally Posted by Mike OReilly

That's a good point rslifkin. If a boat is hitting weight limits for its anchor gear, I'd consider going with lighter chain if that meant the difference between carrying adequate scope, or not.

That's basically what I did on my own boat. I've got the curse of a boat that will carry a ton of weight forward without a trim problem, but also gets slower as you add weight forward (planing hull powerboat). So I ended up settling on a combo of 90 feet of chain, 300 feet of line. I'm a long way away from anywhere with coral, so 90 feet should be enough chain to keep the line from chafing on any rocks or junk on the bottom, and the math says it'll provide enough catenary to get the line to start stretching before the chain is tight, at least at 5:1 scope or better. And I could always use a lighter snubber for a better ride (more stretch at lighter load) at shorter scope if needed.

Keep in mind, a combo like that doesn't work as well with a larger boat and heavier chain unless the boat is pretty high windage. With my 5/16" G43 chain, it doesn't take much to get the splice and the first couple of links off the bottom (a couple knots of wind will do it). But a combo with heavier line and 1/2" chain, for example, wouldn't work as well unless the boat puts a lot more force on it in light winds. So I'd only recommend it when using a high strength chain in the smallest size appropriate for the boat, not when using appropriately sized BBB.

[kmacdonald]

The problem I've had is the anchors not resetting in a wind shift. Most anchors set well when clean of mud. When the they are covered in mud or clay the weight distribution changes and they dont reset well. Size wont help with that. Nothing will.

[Dockhead]

Originally Posted by Lodesman

In those conditions it's doubtful they'd be thinking "I wish I had less chain", either.

I agree!!


I get Dashew's theory, and you can't argue with it in theory.


But I definitely sleep better at night knowing that there is that much more meat on every link of my chain. In real life, links start to rust, start to waste a little, get nicked here and there. And the catenary from 330kg of chain means that a snubber is unnecessary below about 30 knots.