Anchors - Bigger is Better ?

[JonJo]

Originally Posted by Cotemar

USL code as in (Uniform Shipping Laws)?

affirmative

[downunder]

In this document.

http://www.msq.qld.gov.au/~/media/ms...f_usl_pt13.pdf

Page 20 onwards

[downunder]

Full document now attached.

[JonJo]

Down under, thanks!

Continuing on the theme,

Many have reported how they sat our Hurricane, this or that, and how their anchor (oversized) held when everyone else was washed up on the beach. Here our cyclones do not quite reach the size of your hurricanes, but then we are not American (or not yet) Here cyclone zones are well known, cyclones are well forecast and any and everyone has plenty of time to prepare, measured in days, not hours. Here no-one would think of leaving their yacht on one anchor (no matter how oversized), in one of our fiddly little tropical storms. Yachts would be up creeks and if possible tied to mangroves, a web of anchors out, furled sails tied to decks, mainsails off etc. The suggestion from the posts on this thread seems to suggest Americans, or people in America, in the path of a hurricane simply put out their anchor (which is 2 sizes too big) presumably lots of chain and then sit back and, maybe bake the bread. To me this seems to show full confidence in the Big is Better - and shows me up for being too complacent. It would not matter how big my anchor was I would be deploying every bit of ground tackle I had and I would hope to fill in the gaps by tying to trees (but then we do have a cat) if at all possible. At this point I might not wish I had a bigger anchor but that I had more of any anchor!

So - re-confirm for me, anyone who has sat out a hurricane in America simply uses one anchor (and 2 sizes oversize) and this would be common practice for yachtsmen in the path of hurricanes (excluding going into a marina). Equally with a Storm Force wind, Beaufort 10 - the same would be true, one anchor, nothing else?

I might add we sat out a Storm Force wind in Tasmania about 8 years ago (the Duck Pond) - but the wind in the anchorage probably never got above 25 knots - its so sheltered (and we were using our CQR clone (well oversize at 50lb) and we did not drag - but we would never use it now.

[robert sailor]

Nobody that I know or have heard about sits out a full fledged hurricane sitting on the hook in the open because the seas generated would not allow the ground tackle/snubbers etc. to survive. Your cyclones are every bit as powerful as our hurricanes they are simply different names. If you expect to make it through a hurricane here you better be up a back creek or light bulb anchorage and get lucky on top of it. I've heard lots of stories about those on the outskirts of hurricanes who came through fine and later the story is embelished to a full hurricane.

[Jimbo485]

https://www.youtube.com/embed/ePKJAhHWwig

JonJo, check out this video from Airlie Beach when Oswald came thru in Jan 2013. There are relaxed Aussie yachties who don't worry too much when a cyclone is screaming in. Quite sad. Happens every year. What idiot company continues to insure them? BTW, we only got the tail dregs of it in the Brissie River but still had 3 anchors out with 40 - 65 m of rode on the 3 anchors in depths of 4 - 6 m.

[JonJo]

Jimbo,

Scary stuff - worse, if they do have insurance guess whose premiums are paying for their claim (yours and mine)! Our policy does not allow us to travel north of Noosa in the summer without notifying our insurance company, but we can sail 200nm offshore anywhere round Oz in the winter (includes all or most of our islands L Howe etc) and anywhere (except cyclone territory) in the summer. The point being cyclones are a special risk (which is why you and I would use more than one anchor).

[Jimbo485]

Yes, that is why we self-insure. Instead of subsidising a replacement boat for an idiot with only 1 "normal sized" anchor in the water, we can use the $$ for better equipment on our own boat. And we pay more attention because the buck stops with us, not the insurance company. We might regret it one day but are happy so far.

[noelex 77]

There are plenty of bad weather events that would trouble (IMHO likely overwhelm) a normal sized anchor.
Many of these are not forecast.
This is video of a bad one. I was close by, but fortunatunatly not involved in this one that was quite localised.
One cat at anchor, with no sails up, flipped. One yachtsman tragically lost their life when they were crushed between their yacht and one that dragged into them.
http://m.youtube.com/#/watch?v=wSB8z...8zE-guFs&gl=GB

[JonJo]

To summarise,

Most respondents think 'bigger is better' (BIB) is valid.

Strangely few respondents have defined their anchor wardrobe or yacht - and I suspect some support BIB but actually carry recommended sized anchors, so maybe some contradiction

No-one is able to quantify, define, support technically the view that Bigger is Better.

The idea 'BIB' is subjective.

Respondents can quote occasions, some many occasions, when their BIB philosophy has been correct as they have not dragged but people round them have (dragged) but no-one has been able to say the 'draggers' had a small anchor, an old fashioned anchor - or a modern anchor correctly sized, or even a bigger than recommended sized anchor for the vessel.

No-one has been able to quote having bought the 'correctly' sized anchor - found it wanting and bought a bigger one (and been any more safe).

Basically people with big anchors feel comfortable - but interestingly comment has been made that all anchors drag - suggesting even big anchors drag? and that there is still a place for the electronic anchor watch and maybe BIB is not the only answer.

Hurricanes have been quoted as categorical support for BIB, but most people when forecast a hurricane would minimise risk by 'hiding' in a creek and deploying a web of (all) anchors carried. BIB might have been true but supported by Fortress, Spade et al? Eyebrows would be raised of anyone claiming to sit out a hurricane, with the whole yacht exposed to hurricane force winds (as opposed to the wind gear above tree tops) and sitting on one oversized anchor - possible but foolish

No-one is able to suggest why it is that Classification Societies allow SHHP anchors 30% (and I think I read an even higher percentage) smaller than defined in the USL Codes (or the recommendations of most anchor makers) yet the BIB supporters would prefer that all yachtsmen wishing to anchor upwind of them should carry a modern anchor and be 2 sizes bigger (which is an increase of approx 70% by weight, 33kg to 55kg, grudgingly accepting 45kg)

There is little, no?, evidence to suggest that modern anchors, correctly sized for the yacht (as per anchor makers recommendations) have been any more prone to dragging than anchors that are oversized. Any evidence is anecdotal. No-one has admitted to dragging under strong winds with any correctly sized modern anchor - though this might reflect loyalty.

Evidence from South Australia suggest that consideration of upsizing modern anchors (though the evidence is based on the Manson Supreme - but not to reflect on the Supreme more than any other modern anchor) will not solve the problem of anchoring in weed (the answer being an old fashioned Stockless) - negating one reason to buy a larger anchor.

Doubts have been expressed about the applicability of 'holding capacity' data to real life - even though Classification Societies seem pretty convinced.

I might have given the impression of being against the carrying of oversized anchors. As expressed by someone earlier - if it makes people feel happy, great - anyone who supports anchor makers gets my vote! I'm happy with quality in small packages, and more than one of them (I like my eggs in more than one basket - we carry at least 3 anchors each of which individually is 'correctly' sized for our yacht). But each to their own. I'm not so comfortable with the idea a view can take hold without more substance, so it might be fully valid - but I would like to see more substance. I would also like to see some basis that a yacht coded to take a 33kg anchor can safely set a 55kg version - given that it might be set inadequately prior to a change of tide or wind. I would like to see that yachts coded to take a 33kg anchor can 'take' a 55kg anchor loaded with seabed (a recent and frank admission on another thread).

[s/v Jedi]

Let's go into a marina:


Let's haul-out:


Anchored cat:


Anchored cats all did bad, i.e. flipped:


Tie to mangroves; here the big boat is pulling them off again, but about 30% of them needed repairs first, i.e. holed:


Typical cat in mangroves; they do well but make sure there's no rocks underneath because it's 99.9% sure you will be on the mangroves as holding off with anchors mostly fail when the wind comes broadsidesame for mono's)


This is all Hurricane Ivan in Grenada in 2004. This was a cat4 storm turning into cat5 as the eye passed over the south coast of Grenada, direct hit. The island was destroyed, 120 knots sustained winds with 140+ knots in gust and countless tornadoes that come with such storms. All the boats that just anchored were lost, sunk, on a reef or set ashore. Only the biggest cats did not flip at anchor or mooring. Light weight is not good during these storms so make sure to secure every side of your cat, using anchors or drive it hard into a mangrove channel to get mangroves at three sides of the boat. Even if that leads to a bit of damage.

Do tie to the mangroves with a spiderweb of lines and every anchor you have. Use chain around mangroves, we kept lengths of it, with shackles etc. aboard during stay in hurricane areas.

Do not try to sail away; there will most probably be no wind. You will need to motor. Many boats destroyed in Greneda came south to hide while they would have been safe where they were. If you take off, keep going towards the equator until you are sure the storm clears you, then head for protection. I personally don't believe that Trinidad is safe. Commercial interests will make sure most do believe it's safe, but hurricanes have passed in between Trinidad and Tobago, showing it is just a lottery but the chances are a bit better in Trini. Same for ABC's.

The reason that Jedi survived this storm at anchor is not just a big anchor. Everything needs to be tuned to the same class and weight of gear: the windlass, chainstopper, anchor roller etc. The only boats built like this that I know of are the Dashew designs.
The only reason that Jedi was at anchor was that Grenada was considered safe (it regained that status again for some stupid reason) and only our three cats were aboard. If we would have been aboard, we would have been in the mangroves, like we were at other "events".

Here's the complete gallery link for those who want to see more:
http://sv-jedi.smugmug.com/Archive/2...1076784_Z45Mwb

[Dockhead]

Originally Posted by JonJo

To summarise,

Most respondents think 'bigger is better' (BIB) is valid.

Strangely few respondents have defined their anchor wardrobe or yacht - and I suspect some support BIB but actually carry recommended sized anchors, so maybe some contradiction

No-one is able to quantify, define, support technically the view that Bigger is Better.

The idea 'BIB' is subjective.

Respondents can quote occasions, some many occasions, when their BIB philosophy has been correct as they have not dragged but people round them have (dragged) but no-one has been able to say the 'draggers' had a small anchor, an old fashioned anchor - or a modern anchor correctly sized, or even a bigger than recommended sized anchor for the vessel.

No-one has been able to quote having bought the 'correctly' sized anchor - found it wanting and bought a bigger one (and been any more safe).

Basically people with big anchors feel comfortable - but interestingly comment has been made that all anchors drag - suggesting even big anchors drag? and that there is still a place for the electronic anchor watch and maybe BIB is not the only answer.

Hurricanes have been quoted as categorical support for BIB, but most people when forecast a hurricane would minimise risk by 'hiding' in a creek and deploying a web of (all) anchors carried. BIB might have been true but supported by Fortress, Spade et al? Eyebrows would be raised of anyone claiming to sit out a hurricane, with the whole yacht exposed to hurricane force winds (as opposed to the wind gear above tree tops) and sitting on one oversized anchor - possible but foolish

No-one is able to suggest why it is that Classification Societies allow SHHP anchors 30% (and I think I read an even higher percentage) smaller than defined in the USL Codes (or the recommendations of most anchor makers) yet the BIB supporters would prefer that all yachtsmen wishing to anchor upwind of them should carry a modern anchor and be 2 sizes bigger (which is an increase of approx 70% by weight, 33kg to 55kg, grudgingly accepting 45kg)

There is little, no?, evidence to suggest that modern anchors, correctly sized for the yacht (as per anchor makers recommendations) have been any more prone to dragging than anchors that are oversized. Any evidence is anecdotal. No-one has admitted to dragging under strong winds with any correctly sized modern anchor - though this might reflect loyalty.

Evidence from South Australia suggest that consideration of upsizing modern anchors (though the evidence is based on the Manson Supreme - but not to reflect on the Supreme more than any other modern anchor) will not solve the problem of anchoring in weed (the answer being an old fashioned Stockless) - negating one reason to buy a larger anchor.

Doubts have been expressed about the applicability of 'holding capacity' data to real life - even though Classification Societies seem pretty convinced.

I might have given the impression of being against the carrying of oversized anchors. As expressed by someone earlier - if it makes people feel happy, great - anyone who supports anchor makers gets my vote! I'm happy with quality in small packages, and more than one of them (I like my eggs in more than one basket - we carry at least 3 anchors each of which individually is 'correctly' sized for our yacht). But each to their own. I'm not so comfortable with the idea a view can take hold without more substance, so it might be fully valid - but I would like to see more substance. I would also like to see some basis that a yacht coded to take a 33kg anchor can safely set a 55kg version - given that it might be set inadequately prior to a change of tide or wind. I would like to see that yachts coded to take a 33kg anchor can 'take' a 55kg anchor loaded with seabed (a recent and frank admission on another thread).

Well, I think one reason why people think "bigger is better" is because some people believe that anchors work disproportionately better as they get larger. The holding effects do not scale linearly. Now I can't prove it, but this seems true to me based on my experience, and I read it somewhere (I think in the Smiths' Rocna Anchor Resources site, which I respect very much). Therefore, some people are willing to spend more and struggle with their anchors more, to have one a size up which they expect will hold better than the 10% or whatever which is the difference in size.

Now my anchor is not now actually oversized, if you accept Spade's recommendations (which are much more conservative than those of other makers). My boat falls in the middle between two categories -- 20 tons and 30 tons displacement. Spade recommend, for "extensive cruising and difficult seabeds", 30kg for a 20 ton boat, and 55kg for a 30 ton boat. I have their S180, which is a 44kg anchor. Rocna recommend 40kg for my boat (and my last anchor was one size up from that at 55kg). These recommendations are much heavier than standards of yore. Lewmar, for example, recommended a 25kg (!) Delta for my boat, which is what she was delivered with (!).

Why should that be, if these new anchors work so much better? Well, standards have changed. People have powered windlasses, and they really expect to be able to sleep at anchor nowadays. Back in the day, you kept an anchor vigil if there was any chance of any weather. Nowadays, if the seabed is decent and you've got decent shelter, you set an anchor alarm and go to bed. In my opinion, this is real progress.


In my opinion, although bigger anchors obviously hold better and I think probably disproportionately so, they can be harder to set, especially in weed. At least, that has been my experience. My 55kg Rocna was not particularly easy to set in any seabed (besides weed, it really didn't like soft mud, but once set it never budged). My 15kg Spade on my previous boat was much easier to set than the 44kg Spade on my present boat. I have actually only had one complete failure to set with the present anchor after multiple attempts which required me to move to another part of the anchorage -- coincidentally, I was trying to anchor right next to our own Kenomac, in Guernsey, as we later figured out (we didn't know each other at the time). Ironically, Kenomac was lying to a CQR.

So it's obviously a tradeoff (like everything with boats). JonJo might be right in a few cases -- people whose anchors are so big that not only are they hard to handle, but hard to set properly, and maybe don't actually get set properly. Maybe some people anchor a lot in weed (I certainly try to avoid it), where bigger anchors may objectively be worse. But I think these cases are very rare. I think for 99% of cases, the biggest anchor you can handle reasonably well is going to be the best anchor for the job.

[s/v Jedi]

When you relate anchor holding to the surface area of it's flukes, the holding increases squared. I.e. an anchor with twice the surface area holds 4x better.

This is same as for forces on a sail etc.

[barnakiel]

Originally Posted by s/v Jedi

When you relate anchor holding to the surface area of it's flukes, the holding increases squared. I.e. an anchor with twice the surface area holds 4x better.

This is same as for forces on a sail etc.

I lost it here. I thought the square relationship is towards:

a) wind force, (2 times faster wind = 4 times the force),
b) linear size of the area (an object 2 times longer/broader = 4 times the surface = 4 times the force)

When you say "an anchor with twice the surface area holds 4x better" - do you mean what you say?

I believe that an anchor with twice the surface area (say 1 sq m vs. 2 sq m) holds twice better, caeteris paribus. Because the holding is proportional to the area.

Imagine two anchors of same size - will their joint holding force be quadrupled? (mathematically, not empirically)

barnakiel

[s/v Jedi]

Yep, wanted to write twice the size but got to write surface area too often

So let me try again:

An anchor twice the size holds four times better.

cheers,
Nick.

Originally Posted by barnakiel

I lost it here. I thought the square relationship is towards:

a) wind force, (2 times faster wind = 4 times the force),
b) linear size of the area (an object 2 times longer/broader = 4 times the surface = 4 times the force)

When you say "an anchor with twice the surface area holds 4x better" - do you mean what you say?

I believe that an anchor with twice the surface area (say 1 sq m vs. 2 sq m) holds twice better, caeteris paribus. Because the holding is proportional to the area.

Imagine two anchors of same size - will their joint holding force be quadrupled? (mathematically, not empirically)

barnakiel