Panope Rocna video

[Neeves]

Pete,

If you are trying to imply that I don't know what I am talking g about and I am massaging reality - if I have misjudged, if my data is wrong I need to know - or I will be repeating these errors again and again. I value feedback and as YOU have raised the issue I expect you to provide detail to support your criticism.

Please define exactly where I have gone wrong. I have the data on Mantus, the conclusions are supported by other individuals and organisations. If you want to argue with the US Navy research centre, Universities in Houston- be my guest etc - but do allow all of us to view the correspondence. I need to learn from someone with your skills and background knowledge. Knowledge is of little value if it is not shared and I for one would like to learn from you - so that I may not repeat my mistakes in the future. I'm not one to silence dissent, I cannot support the idea of denying airing of alternative views - dissent and alternative views allows us to explore concepts - So, I welcome your criticism - please put some data behind it that we all may enjoy your ideas and we all may learn.

In fact if you have any data at all - please let us all view it.

You suggest I am trashing Rocna - please tell me what I have said that is different to that illustrated on the Panope video or that has been said by AAC aka Morgan's Cloud. I assume you have castigated Morgan's Cloud and Panope in a similar vein. Again - I am sure we would all like to see the correspondence and how Panope and AAC have replied - again - I am here to learn (as are we all).

Humbly,

Jonathan

 

[Pete7]

Pete, If you are trying to imply that I don't know what I am talking g about and I am massaging reality

I must refer the honourable gentleman to a quote by Francis Ewan Urquhart :

"You might think that. I couldn't possibly comment"

If you are suggesting that someone with a NG anchor like a Rocna should now change it due to potential flaw, then I think you are 'barking' it's not going to happen. After all, no anchor is perfect, even you implied that saying they are "a compromise". After all it has taken 2 decades for folk to come around to the idea that a worn out wonky CQR or Bruce copy isn't an ideal anchor and that there is better. We have to thank the late Prof Knox, Peter Smith and the much-maligned Craig Smith, were did he go? Oh and I suppose we should acknowledge that Journo from down under with the initials JN, annoying as he can be.

You asked about data, well I have very little other than some personal observations of using a Delta and then for the last 6 years a Rocna. We never dragged using a 10kg Delta on a 31ft yacht, but then we always chose protected areas to anchor and will continue to do so. At 5100kgs any fetch just makes life uncomfortable on board a small yacht. So whilst the delta never dragged the mud and sand marks revealed that only the first 6-8" of the tip had dug in.

Reading the various anchor tests over the years suggested that a NG anchor would have a much higher holding power for a similar size and weight. The cost of changing to a new 10kg Rocna and selling the Delta, about £110 in 2014, so potentially lots to gain for a sensible outlay. I note that the Rocna price has since doubled. Sadly the Spade was out of budget, one day perhaps. We do carry a FX16 but have only used it a couple of times.

The Rocna has dragged once, in Studland Bay. We hit a patch of eel grass and had to lift and anchor again succeeding the second time. I believe there are very few anchors that will work in these conditions, but Skip Novak's 110lb CQRs might make a decent hole to dig in. Equally a fisherman's anchor perhaps. We have one decorating the garden pond, it could be taken into use.

There is one further advantage, by keeping to the same size and weight but higher holding power, I was able to continue to keep the anchor in the anchor locker. It's out of the way and secure, yet a one handed lift to launch when needed. You can't do this with bigger yachts, but smaller yachts can.

My other experiences were anchoring my dive rib frequently. A grapple and 2m of chain would be launched by throwing over the side to free fall to the bottom, often +30m. The rode was thin (8mm) to keep the drag to a minimum in a tide and enable more to be carried in a small space. Scope was known about, but a steep angle was preferred for divers to descend. On more than one occasion we had to go back down to recover the anchor because even a large outboard wouldn't break it out. Quite surprising really, hence my earlier comment about big anchors making a very satisfying thumb into the sea bed. There was no power setting the grapple, we relied on the flukes to either catch something or dig in on impact. It worked, though we did break off a fluke occasionally trying to recover them.

You can see from the photo the Delta has a much thicker shank, but as we now know, that is weight in the wrong place and not in the tip. The greater fluke area of the Rocna is also clearly evident, does this increase holding power?

Anyway, back to 'data'. Here is a photo of my Rocna, a later CMP version I believe. Can we see a photo of your Rocna, you do have one don't you? after all you have posted in this thread. What were your experiences of using a Rocna for several years?


Pete

 

[Neeves]

Pete7

Of course I have a Rocna, if you look through my articles in Practical Sailor you will find it - it took centre stage in one article on Bending of Shanks.. In use I found that it carried mud but that our Spade and our Excel carried less mud. The problems that result, in a concave anchor that is prone to clogging, is illustrated in the article on resetting of anchors and also defined in a recent video by Panope and by AAC aka Morgan's Cloud. So a Rocna holds well, as good as an Excel (of which I have 3 a 5kg, a 15kg steel and a 8kg aluminium version), Supreme (which I also have) and Spade (of which I have 3, a 5kg, a 15kg steel and a A80, 8kg). But because the Rocna and Supreme both carry mud and require copious use of the deck wash to clean I prefer to use an anchor that does not carry mud, Spade and Excel. In addition to the anchors defined I also have CQRs genuine and copies, fisherman etc etc and a couple of Viking. One significant reason why we would not use a Viking, Rocna, Knox, Supreme - they simply do not fit on our bow roller and as our bow roller is structural - we are not going to change it. However like you we use 'light' or small anchors the heaviest are 15kg and it is not difficult to deploy any anchor from our bow by hand and retrieve using the windlass (hooking the anchor onto the bow when it is just below the bow roller.)

All of these anchors, Spade, Excel, Supreme, Rocna, Ultra, Knox, Kobra are good (and yes I also own a Kobra and Knox). Some, or one - Kobra, have slightly less hold (but other redeeming features). The hold of these anchors is superior, for the same weight, as a Delta. But as we both agree - they are all compromises. It is important that those compromises are aired, which is what Panope and AAC have done - in your words 'trashed' the anchor that was then the focus of their investigation - I assume you have criticised them for bring the defects to the public's attention (or did you just single out me? - in which case....why?)

I also have a 15kg Mantus (and a 5kg version) and you will find it has been used by me in various articles in Practical Sailor and found itself centre stage in the investigation on anchor angles. As mentioned it has the hold of not much better than the same sized Delta (but is more easy to set). I see holding capacity as a primary indication of excellence and as there are many anchors with the hold 2 times that of a Mantus (and Delta) I cannot endorse it. Basically it is badly designed. A 'similar' anchor, the Viking shows what good design can do - you can have a steel anchor with high hold - and lower weight. So - if you prioritise hold and lower weight then as well as aluminium anchors the Viking could be part of your choice as a 10kg Viking can have the same hold as a 15kg Rocna or almost twice the hold of a 15kg Mantus.

Copying - as it is bound to come up - as you mentioned it yourself. Bruce patented the roll bar, copied by.... If you lay the fluke of a Rocna on top of a Spade, they have exactly the same plan view (which coincidentally is the same as a Mantus). Delta developed the self righting shank - Spade, Excel and Rocna use the same shank. SARCA introduced the perforated fluke, copied by Panope and used by Viking. Peter Smith emphasised the use of Q&T HT steels used by many - but for the first time in the fluke by Viking. If you look at a Knox - it has an uncanny likeness to a SARCA. So if you want to be critical of copying - you have a lot of targets - just spread your comments or it looks as if you are trolling.

Of course there is not a belief on my part that people will change their existing Rocna for anything else, 9 times out of 10 they are fine. If people are cognisant of the weaknesses of concave, or any, anchors - then hopefully there will be no more yachts on beaches, from this cause. Interestingly some of the comments imply some owners were unaware of the issues of Rocna - I'd thus like to think there is real value in airing these issues - and those that dislike 'bad news' are on a hiding to nothing.

Additionally if people reflect and on changing their yacht need a new anchor hopefully they will take into account the downsides of some anchors, weight up the compromises and make better informed decisions, not necessarily different decision - but better informed decision. I'm not one for suppressing bad news, no burning of books, no banning of people from forum - I call a spade a spade - if there is something wrong - I will say so. But everything I say is based on data and testing - no guessing, no gut feel, no looking at a single picture and offering a damning conclusion - so no trolling.

I think your comment on use of an anchor 'in real life' is very valid - its a pity others don't take note. Too often I see people damning a specific product, never having used one and in some cases never having seen one in use. Maybe you could direct your comments to them, as well.

Pretty pictures do not give you a licence to troll.

As far as I can ascertain Craig Smith accompanies his father on their explorations, last heard of in the NW Passage. He occasionally posts here with a photographic record of their joint exploits (and its impressive). Sadly Peter is of advancing years, it apparently happens to us all, so I don't know how long this lifestyle will last - hopefully a few more years and maybe Craig has found a niche and can continue the adventures (and beguile us with the pictures).

Jonathan

Edit

The media are a funny lot - publishers like to have original work. For this reason I don't do pictures. If I publish pictures here a publisher will not be keen to use the same picture in an article. Publishers pay me for my work but sadly that largesse is not extended to me by YBW nor the members here - so if you want pictures you need to wait till they are published - but I can direct you to the publication, as above.

 

[eddystone]

Interesting that sv Panope has done a video on the (dismissed by some as lacking independent testing results?) Rocna Vulcan and seems quite positive. Actually it's only the second review of any sort I've seen.

 

[steve1963]

An interesting video but in my experience with my Rocna it has never failed to set on first attempt, in all substrates apart from coral, has been tested up to 50 knots gusts and high swell,
I can only go with what I experienced .
And Im no expert in the anchoring , I just do it right.

Umm...should you really be anchoring on coral? This is an extremely destructive practice

 

[FlyingGoose]

Umm...should you really be anchoring on coral? This is an extremely destructive practice

Apart from coral. Kinda gives it away.

 

[Neeves]

I'll be picky.

NormanS made the comment, on a different thread that I could not find, that under the tensions being generated he would have thought the tree would move, or bend. Toward the end of the video Steve is applying a fair amount of tension and in addition to the tree possibly moving I might imagine the nylon strop he mentions (to protect the tree) might also stretch. He also uses a web of rope (not mentioned but in view when he mentions the nylon strop) to secure the strop to the chain. He is making measurements of very small amounts at these high tensions - when his datum point might be moving with greater influence from stretch in the textiles than actual change in the catenary.

I'd suggest the numbers are too low for tension and angles and the distances moved too high.

I've done the same sort of test and with 30m of 8mm chain at a 5:1 scope in air the last link lifts off the horizontal at 84kg which is about the same tension I measure with a similar scope to wind of 17 knots - beyond which all the chain is off the seabed.

In other tests this is the data I recorded. Sadly my testing does not have the excitement of a video - just dry words. If you don't like the words - cut to the graphs. If the script is behind a paywall, for you, let me know (by pm)

Anchor Testing and Rode Loads - Practical Sailor

Jonathan

 

[Neeves]

Jonathan, what do you think about the yaw of the boat, and how much it affects the catenary angles?
I guess that in certain frequencies the yaw effect will change the resoults.

The idea that your yacht sits there 'placidly' with a catenary developed by the direct windage on your yacht is a romantic dream.

All yachts will yaw, because the wind is unstable (when they site wind farms at sea there is a vast investment in research to locate the devices in locations with a minimum of wind shear). Some yachts also have a great propensity to veer, either because of design or because of the real estate added by the owner (dinghy on bow, dodgers, etc.). If your yacht veers the bow on windage suddenly can become 'beam on' windage and your yacht can sail, at anchor. When the yacht sails and reaches the end of its tether the rode can be completely straight, or as straight as makes no difference - and you develop a shock load (unless you are using a decent snubber). Without a snubber I was recording 650kgs at 35 knots (but I had set up my test protocol to define worst case scenarios) and for the appropriately sized old gen anchor this is getting close to uptimate hold (of 1,000kgs).

I, and other amateurs with whom I correspond, think that anchors drag for reasons other than 'apparent' windage on the yacht and that veering and horsing are major contributors (to which I add one of my pet ideas - movement of the yacht reduces shear strength of the seabed at the anchor). This is where measure hold is important - hold is the only numerical piece of data we have on anchor performance and there is strong evidence hold is related to resistance to veering, horsing (and maybe offers better hold when shear strength is reduced). So tests on anchors that exclude hold miss the only numerical piece of data available for anchors.

The absence of hold is a bit like selling a car without fuel (battery or petrol consumption data). Yes it looks sexy, it hold the correct number of people but many of use want a car that is economical to run - and would not buy one if its 'fuel' consumption is high. So why would you buy an anchor with no hold data, why would you bow at the feet of the guru if he recommends an anchor whose hold data he does not know?

We have evidence from users, the people here, that old gen anchors have lower hold and have higher propensity to drag than some new gen anchors that have high hold. The suggestion is high hold results in anchors that are more reliable and as all yachts veer, greater or lessor and if veering etc causes dragging then high hold is desirable and measureing the hold, essential. A test and a conclusion without hold misses, to me, the key perameter. There are a number of conclusions on some anchors that they are 'good' or 'bad' - without hold data these conclusion are lacking in completeness - and in some cases where hold has been measured, after the event, the conclusions are dangerously wrong. So if someone recommends an anchor - ask about hold - in the absence of any hold characteristics - walk away (there are plenty of options WITH hold data).

Your rode does not work with each component working in isolation, catenary is simply one component. Scope is another and your use, or not, of snubbers a further facet. Elasticity and catenary work together. Like you car - you do not simply rely on shock absorbers but also the upholstery that you sit on (and the upholstery is 'complex, relying on springs and foam) etc. Long, elastic snubbers do seem to tame the vibrations that pass down the steel chain - so a snubber might minimise the reduction in shear strength of seabed at your anchor. I can only comment on long elastic snubbers, because I have not tried short, less elastic, snubbers and tested for vibration down the rode.


But of anchors - to me you want the highest hold available for the least weight and cost. High hold is developed by the windage of the yacht and the deeper the anchor can 'dive' (into the high shear strength lower levels of the seabed) and the more chain you can bury the greater the anchor will offer in resisting veering and horsing.

Most modern anchors work well with high tension angles - don't get hung up over catenary, don't ignore it - but also consider how you can ensure your anchor can dive as deeply as possible and think again about your snubber(s).

Think also about veering - hold is measured in a straight line pull, if you veer the pull is sideways. Think how you can reduce veering (buying a bigger heavier yacht is one method (sadly not sensibly available to most!)

Jonathan

 

[geem]

Not true. Actually I bought a Rocna because it was half the price of the Spade and available locally, 200 yards from the boat. Will I now change it in light that if a large mud ball sticks to it and if the tide turns and we have 55 knots? ........No. The forecasting for NW Europe is really good enabling you run away and hide. If we ever go "off piste" as you say then well I might buy the next size up Spade for that just in case situation, best to be safe

We were cruising in the Bahamas three years ago in company with friends who have a Rocna. We were anchored close to each other, with them up wind of us. It was a lovely sunny day with light winds. We had been anchored in the same spot for three days. Our friends were down below when I noticed they seem to be dragging. I jumped in the dinghy a whizzed over to inform them by which time they were clearly dragging towards us. I was alongside their yacht when they lifted their Rocna. It was encased in a ball of hard sticky grey mud. Our friends couldn’t believe it. The conditions were benign and they had been in the same spot with stronger winds for three days.
It wasn't a tide issue or blowing 55kts. More like 10kts

 

[Neeves]

Geem, you are like us - when its forecast to be challenging at anchor we too wimp off and hide. Others suggest this is wrong - one should brazen it out and gain bragging rights.

We don't doubt our choice of groundtackle at all - but its not a competition and sailing is meant to be a pleasure not part of an SAS acceptance course.

If you want to know what the local chandler sells in terms of anchor - go and look at anchors on the bow roller in the local marina. many buy what is available locally.

Jonathan