How should I anchor?

[NormanS]

A 45' AWB with no added windage over the standard yacht, say a Bav 45 with 30m of 8mm chain deployed at a 5:1 scope and enjoying around 17 knots of wind has a tension of about 68kgs in the rode and the very last link, at the anchor shackle will be 'just' lifted of the seabed - this is the sort of tension a reasonable fit individual mightl hold - at least temporarily. This is a simple all chain rode, no snubber. I have measured the tension of such a rode, no snubber, at 17 knots and I have measured the tension. necessary to lift the last link off the seabed. You tell me that you experience many 10s of knots of wind in anchorages in the Western Isles - I suspect you might agree that 68kgs of tension is 'light' - but maybe you will want to indicate that this is heavy - if so please define 300kgs of tension, the maximum I measured was 650kg (at 35 knots) - and I chickened out at that point.

I do accept that it is all relative., heavy, light etc etc - Zoidberg, Post 76 did make the observation that terminology might lead to some confusion, maybe a case in point.

Jonathan

Jonathan, while greatly respecting your knowledge and expertise on these matters, as you know we see some aspects rather differently. If I had a Bav 45, there is absolutely no way that I would be using 8mm chain for an anchor rode. I am still old fashioned enough to believe in the benefits of catenary, and accept that that requires the use of suitable chain for the purpose.
I accept that some boats, particularly light weight boats where every gram of weight carried is a handicap, find it necessary to compromise, for those of us with more traditional craft, the actual difference between light and heavy chain is of little consequence.
By all means carry on with your crusade for light weight high tech chain and the resultant requirement for cat's cradles of snubbers strewn around decks, for your light weight and multihull brethren, but please remember that such methods are not appropriate for all boats. Our own boat, for example, carries three tons of ballast around, so a few extra kilos of chain is neither here nor there.
A happy New Year to you and yours, when it comes, which won't be long in your case. ???

 

[Neeves]

There was no suggestion a Bav 45 would use 8mm chain.

Our catamaran has the windage of a Bav 45 (I've measured them both) and as few people on this forum have a catamaran I have need to offer a yacht that has similarities to ours. They can then relate what I say to their own situation. If they use heavier chain, I guess 10mm, they could use a catenary calculator and work out the tension needed. At the time I did the measurements I only had 8mm chain and was not about to go off and buy 10mm chain to make another calculation. The 8mm chain is standard for Lightwave 38 though some have used 10mm. I have just been involved in making a 'lightweight' High Tensile 8mm chain for an Ovni 43, a 6mm lightweight HT chain for a 50' tri. Previously I was involved in a 8mm HT lightweight chain for a 50' cat and we of course now use HT 6mm chain.

I think you might find there are more people using lightweight G70 chain on YBW than is first evident.

Access to new materials and technology is not standing still, people are more accepting of lighter HT chain (and snubbers) than you think.

But to put the 68kg in another or different perspective.

I have also measured the tension developed by our engines and they roughly, or crudely, work out at about 10hp produces about 100kg of tension, 3 bladed folding Volvo props. So the tension of 68kg is considerably less than would be developed by the engine of any yacht using 8mm chain and who power set. Consider an owner might power set his anchor, with 8mm chain, on his yacht supplied with a 40hp engine and use 75% of max revs - the tension would be about 300kg - I consider 68kg - light. He of course is hoping that the winds get nowhere near developing a tension of 300kgs and will be more than happy if the winds are light, and the tension never exceeds a 'light' 68kgs. A 15kg anchor, new gen will hold about 2,000kg - its ultimate holding capacity. A 15kg Delta has a UHC of about 1,000kgs

Based on this data I would say that the tension needed to lift the last link of the seabed is 'light' whether its 6mm, 8m or 12mm - its all relative and this will occur, assuming the chain size vessel size spreadsheets are about right at the equivalent to about 17knots, maybe 20 knots and I would say that the tension needed to lift that last link is light compared to the tension developed at 30 knots.

Jonathan

 

[RupertW]

Jonathan, while greatly respecting your knowledge and expertise on these matters, as you know we see some aspects rather differently. If I had a Bav 45, there is absolutely no way that I would be using 8mm chain for an anchor rode. I am still old fashioned enough to believe in the benefits of catenary, and accept that that requires the use of suitable chain for the purpose.

It’s not old fashioned to believe in catenary and heavier chain it is demonstrably bonkers, making no sense from the maths and none from observation. If you can’t see that the exponential forces required to remove the last bit of curve make the chain effectively a steel bar, and that this happens at moderate wind speeds then you are doing what the best anchors do, burying your head in the sand.

 

[NormanS]

There was no suggestion a Bav 45 would use 8mm chain.

Our catamaran has the windage of a Bav 45 (I've measured them both) and as few people on this forum have a catamaran I have need to offer a yacht that has similarities to ours. They can then relate what I say to their own situation. If they use heavier chain, I guess 10mm, they could use a catenary calculator and work out the tension needed. At the time I did the measurements I only had 8mm chain and was not about to go off and buy 10mm chain to make another calculation. The 8mm chain is standard for Lightwave 38 though some have used 10mm. I have just been involved in making a 'lightweight' High Tensile 8mm chain for an Ovni 43, a 6mm lightweight HT chain for a 50' tri. Previously I was involved in a 8mm HT lightweight chain for a 50' cat and we of course now use HT 6mm chain.

I think you might find there are more people using lightweight G70 chain on YBW than is first evident.

Access to new materials and technology is not standing still, people are more accepting of lighter HT chain (and snubbers) than you think.

But to put the 68kg in another or different perspective.

I have also measured the tension developed by our engines and they roughly, or crudely, work out at about 10hp produces about 100kg of tension, 3 bladed folding Volvo props. So the tension of 68kg is considerably less than would be developed by the engine of any yacht using 8mm chain and who power set. Consider an owner might power set his anchor, with 8mm chain, on his yacht supplied with a 40hp engine and use 75% of max revs - the tension would be about 300kg - I consider 68kg - light. He of course is hoping that the winds get nowhere near developing a tension of 300kgs and will be more than happy if the winds are light, and the tension never exceeds a 'light' 68kgs. A 15kg anchor, new gen will hold about 2,000kg - its ultimate holding capacity. A 15kg Delta has a UHC of about 1,000kgs

Based on this data I would say that the tension needed to lift the last link of the seabed is 'light' whether its 6mm, 8m or 12mm - its all relative and this will occur, assuming the chain size vessel size spreadsheets are about right at the equivalent to about 17knots, maybe 20 knots and I would say that the tension needed to lift that last link is light compared to the tension developed at 30 knots.

Jonathan

So did I misread your first sentence in #80?

 

[NormanS]

It’s not old fashioned to believe in catenary and heavier chain it is demonstrably bonkers, making no sense from the maths and none from observation. If you can’t see that the exponential forces required to remove the last bit of curve make the chain effectively a steel bar, and that this happens at moderate wind speeds then you are doing what the best anchors do, burying your head in the sand.

Each to their own. ? HNY.

 

[geem]

Jonathan, while greatly respecting your knowledge and expertise on these matters, as you know we see some aspects rather differently. If I had a Bav 45, there is absolutely no way that I would be using 8mm chain for an anchor rode. I am still old fashioned enough to believe in the benefits of catenary, and accept that that requires the use of suitable chain for the purpose.
I accept that some boats, particularly light weight boats where every gram of weight carried is a handicap, find it necessary to compromise, for those of us with more traditional craft, the actual difference between light and heavy chain is of little consequence.
By all means carry on with your crusade for light weight high tech chain and the resultant requirement for cat's cradles of snubbers strewn around decks, for your light weight and multihull brethren, but please remember that such methods are not appropriate for all boats. Our own boat, for example, carries three tons of ballast around, so a few extra kilos of chain is neither here nor there.
A happy New Year to you and yours, when it comes, which won't be long in your case. ???

Our 44ft Van de Stadt has 6 tons of ballast in the keel but we still dont believe in carrying more weight in the bow than necessary and we use long snubbers as a matter of course?

 

[Neeves]

So did I misread your first sentence in #80?

I don't know

But it reads as I wrote it: if a Bav 45 had a 8mm chain and deployed it as described the tension in 17 knots would be 68kgs. There was no suggestion 8mm was ideal, or not. But the Bav 45 has a similar windage as us and if it happened to anchor as described that would be the tension at around 17 knots. I measured the tension on 30m of 8mm deployed as described, being careful to lift that last link, I measure the tension in the, same, rode at 17 knots. I compared the windage of the 2 yachts. I used the same load cell (and the same chain) for the measurement. I unfortunately don't have access to a Bav 45 or I would have conducted a whole series of measurements with one - but I did have access to the drawings from Bavaria (and a Bav 35) plus those of our own cat.

Now I confess I take some liberties as the Bav is much heavier and has a deep keel (compared to ours) - its meant to be indicative.


Having raced a Plastic Fantastic I am conscious of the impact of carrying extra weight, especially in the ends. Modern yachts, like a Bav (or Jenny or Benny) have had all the extra weight squeezed out of them and I firmly believe that they will all perform better with attention to weight, and its distribution. No-one would sail to windward with a crew member standing on the bow, so why sail with extra (chain) weight when a smaller (high tensile chain) and a decent snubber (which weighs peanuts) would actually (I believe) provide a more comfortable anchoring experience. So my use of 8mm is not far fetched, as underlined by the Ovni 43 that has down sized from 10mm to 8mm (and the owner is one of Australia's foremost boat builders).

Take care and stay safe - all of you. Enjoy our fireworks, its 11pm here and we have a shorted version to look forward to at mid night (but restricted to TV viewing (the Harbour is sealed off with security fencing)

May next year start to look like we recall of 'Normal'.

Jonathan

 

[claymore]

I am stunned that such a well hackneyed post can still get 87 responses after 20 years. ?

 

[Neeves]

I am stunned that such a well hackneyed post can still get 87 responses after 20 years. ?

???

Its too clever for me - maybe you can explain.

Jonathan

and keep the thread fresh

 

[Neeves]

Its interesting but people complain that old fashioned paper published sailing magazines produce the same articles as 3, 6, 10 years previous, whether its on yacht handling under motor, anchoring, sail trim etc. Yet with a much higher frequency we have new threads here querying, handling under motor, anchoring, sail trim etc. Worse - there are electronic publications, blogs, etc of the exploits of owners underlining people don't know, they have not learnt and they also don't appear to know how to use a search function. To protect the individuals I'm not going to point any fingers and I am not thinking of anyone in particular (so just because the cap fits - don't worry ).

If you read threads on YBW it is obvious that some members who joined early on in YBW's history and have many thousands of posts, and newer members - completely ignore the science and completely ignore the search function - providing a background to the constant repetition. Another factor is - technology, or the use of technology, even in sailing...... 20 years is a long time, foiling, SUPs, concave anchors, LEDs, broadband radar, - some of which underpin a repetitive article, on say yacht lights and marine lighting.

There are equally other facets of sailing technology that were to be the best thing since sliced bread, winged and tandem keels being an example - that obviously did not excite, ultra - sonic AF - and I for one, wonder why (as there was obviously something positive behind the ideas) - offering opportunity (in this case) for another article in PBO or YM on keels and design or of AF encompassing what's new today, silicone, what's mainstream and what fell by the wayside (and why).

Plus ca change!

Jonathan

 

[claymore]

OK
There have been a constant stream of threads about anchoring on here over the past 20 years. I am amazed that there is still something to say or a question to ask. That is what I was saying.
I think it might be good if users of the forums were to use the search facility then rather than keeping this thread fresh, we might get some fresh threads.
Hope that explains my post
Happy New Year - Sydney looked great on New Year's Eve - although it seemed strange that you were celebrating it as we were having lunch

 

[claymore]

Its interesting but people complain that old fashioned paper published sailing magazines produce the same articles as 3, 6, 10 years previous, whether its on yacht handling under motor, anchoring, sail trim etc. Yet with a much higher frequency we have new threads here querying, handling under motor, anchoring, sail trim etc. Worse - there are electronic publications, blogs, etc of the exploits of owners underlining people don't know, they have not learnt and they also don't appear to know how to use a search function. To protect the individuals I'm not going to point any fingers and I am not thinking of anyone in particular (so just because the cap fits - don't worry ).

If you read threads on YBW it is obvious that some members who joined early on in YBW's history and have many thousands of posts, and newer members - completely ignore the science and completely ignore the search function - providing a background to the constant repetition. Another factor is - technology, or the use of technology, even in sailing...... 20 years is a long time, foiling, SUPs, concave anchors, LEDs, broadband radar, - some of which underpin a repetitive article, on say yacht lights and marine lighting.

There are equally other facets of sailing technology that were to be the best thing since sliced bread, winged and tandem keels being an example - that obviously did not excite, ultra - sonic AF - and I for one, wonder why (as there was obviously something positive behind the ideas) - offering opportunity (in this case) for another article in PBO or YM on keels and design or of AF encompassing what's new today, silicone, what's mainstream and what fell by the wayside (and why).

Plus ca change!

Jonathan

You make your point well - indeed some things have changed drastically, foils, carbon fibre, navigation software but with anchoring - apart from a few changes in design - the principle of sticking a hook into the seabed and allowing sufficient scope to deal with the rise and fall of tide, the proximity of neighbours and reefs, none of this has changed! Its all been said - time and again...

 

[Neeves]

Happy New Year - Sydney looked great on New Year's Eve - although it seemed strange that you were celebrating it as we were having lunch

I did not mention carbon fibre nor chart plotters as they were both used prior to 20 years ago. However I was noticing yesterday that though carbon fibre was exclusively 'exotic' I detect that here it is almost mainstream. No longer the exclusive use of the serious fraternity of racers.

We do put on a good show, at a very convenient time for you - and an uncivilised hour for us - especially as the weather has been more like Manchester than Sydney and we are all effectively in lock down and only able to entertain minimalistically and restricted to neighbours. All very strange.

Yes - you really are behind the times . But its something you cannot change, unlike anchoring where there have been 'possible' changes and 'improvements', like snubbers and high tensile chain.

Both are not new, HT chain has been championed for decades - but the yachting fraternity are desperately reactionary, Luddites comes to mind, There is science behind both ideas, not veery complicated science - but the old mantra is constantly preached (as the only way) without mention of the alternatives. In fact people will happily argue against the alternative of HT chain and snubbers even after the science is presented to them.

And thus we have constantly repeated threads.

Jonathan

 

[Ravi]

Amazing how quiet Christmas is fo click bait..

A "Hypothetical post from Fascadale gets loads of replies to an ..... anchoring !!!!!! question!

I am convinced that there are aliens on another planet who have competitions about how many responses they can get from posting anchoring questions on forums.

 

[Neeves]

Amazing how quiet Christmas is fo click bait..

A "Hypothetical post from Fascadale gets loads of replies to an ..... anchoring !!!!!! question!

I am convinced that there are aliens on another planet who have competitions about how many responses they can get from posting anchoring questions on forums.

Nope, my guess is much simpler

My guess was Fascadale read this article:

Safety at Sea: Surviving a Powerful Storm in the Med

turned it into a, or series of, hypothetical question(s)

and the rest is history.

Jonathan

You are simply increasing the reply count (for which, unknown to me (he is to receive beers from the ether ).

 

[geem]

I did not mention carbon fibre nor chart plotters as they were both used prior to 20 years ago. However I was noticing yesterday that though carbon fibre was exclusively 'exotic' I detect that here it is almost mainstream. No longer the exclusive use of the serious fraternity of racers.

We do put on a good show, at a very convenient time for you - and an uncivilised hour for us - especially as the weather has been more like Manchester than Sydney and we are all effectively in lock down and only able to entertain minimalistically and restricted to neighbours. All very strange.

Yes - you really are behind the times . But its something you cannot change, unlike anchoring where there have been 'possible' changes and 'improvements', like snubbers and high tensile chain.

Both are not new, HT chain has been championed for decades - but the yachting fraternity are desperately reactionary, Luddites comes to mind, There is science behind both ideas, not veery complicated science - but the old mantra is constantly preached (as the only way) without mention of the alternatives. In fact people will happily argue against the alternative of HT chain and snubbers even after the science is presented to them.

And thus we have constantly repeated threads.

Jonathan

I think we would actually be happy to use High tensile chain and take the weight saving in the bow. However, we spend so much time at anchor that the corrosion aspect of galvanised HT chain is a concern. Our normal cruising ground of the Caribbean is not a place where galvanising is possible. The only place I know is in Colombia. For this reason we stay with G43 10mm chain that is relatively cheap. Once the chain is rusty we replace it and at the moment that is about every four years.
With regard to carbon fibre. My tender is now approaching 28 years old. Its a mix of carbon and polyester cloth. It must have been way ahead of its time. I wonder if it the first use of carbon in yacht tender history?.
We have been using long snubbers on our boats for 18 years so maybe an early adopter. We originally used cheap polypropylene rope as a long snubber on our catamaran for it stretchiness. It worked quite well but was not very durable?

 

[Neeves]

I think we would actually be happy to use High tensile chain and take the weight saving in the bow. However, we spend so much time at anchor that the corrosion aspect of galvanised HT chain is a concern. Our normal cruising ground of the Caribbean is not a place where galvanising is possible. The only place I know is in Colombia. For this reason we stay with G43 10mm chain that is relatively cheap. Once the chain is rusty we replace it and at the moment that is about every four years.
With regard to carbon fibre. My tender is now approaching 28 years old. Its a mix of carbon and polyester cloth. It must have been way ahead of its time. I wonder if it the first use of carbon in yacht tender history?.
We have been using long snubbers on our boats for 18 years so maybe an early adopter. We originally used cheap polypropylene rope as a long snubber on our catamaran for it stretchiness. It worked quite well but was not very durable?

You can regalvanise G70 chain, it will do it no harm (so I was told by a manufacturer of G70 and I tested it myself and my results confirm their comments). You can buy G70 chain in the Caribbean (though I guess more expensive than G43), - but if you use 3/8th" G43 you could replace it with 5/16th" G70 (+ buy a new gypsy) - and there is a 'saving' as you are buying smaller chain. G70 chain will lose its galvanising at the same rate as G43 and 4 years life full time at anchor - is about right. The problem would be that metric chain might be more difficult to source than Imperial - but Peerless, the USA's biggest chain maker, make both metric and imperial sizes (still that question mark on stock in the Caribbean) and make the original G70 through their ACCO site. The corrosion rate of G43 and G70 will be the same, or you will not detect a difference - the steel used for both chains is almost identical, the difference is a boron addition and the G70 is Quench and Tempered (Imparting the strength).

Maggi's G70 was a different beast - I think it was based on a G100 feedstock, a different steel. But it too could be safely regalvanised. However Maggi went through an 'administrator' (staves of bankruptcy) and I think is in different hands. Last I heard the ex MD, one of the Maggi family was working for Kito (who now own Peerless) and he worked at Kito Italy at their Weissenfels factory (in Italy). The few people, all 2 of them, who have mentioned Maggi gal life one has reported 4 years for G70 and the other 4 years for G40. This is hardly statistically sound but adding Geems figures is helping to build a picture. The story of Maggi chain having a poor gal life was based on incorrect information - and was probably an unfair slur on Maggi (and might have contributed to the administrator being called in)

I think any of us using long snubbers went through a learning process as initially it was a novel and frowned upon (has anything changed) and we all experimented. I will not say that our particular practice is the final solution - watch this space (or further threads).

Jonathan

I've just checked, ex store from West Marine

3/8th" G70 US$11/ft
5/16th" G70 US$6.5/ft

3/8th" G43 US$7/ft

I suspect if you down sized from G43 to G70 and scrapped your chain after 4 years then the savings on your next chain replacement would fund the new gypsy, and leave you some change. You save on weight, space, lower electrical usage (if push comes to shove it would be easier to retrieve by hand) and if you made the investment at commissioning you could buy a smaller windlass, though I'd actually suggest you option the 3/8th' windlass, with a smaller gypsy, not the 5/16th" windlass. But you do need to use a decent snubber (as Geem does anyway) and believe in the fallibility of catenary.

 

[Neeves]

Ravi and Claymore - has everything on this thread been known to you? If you knew it all - why don't you both contribute more of your knowledge. None of us knows it all - and most of us are more than happy to learn.



Jonathan

 

[claymore]

In truth and without sounding an arse - speaking directly to the letter of the original post , there really is nothing in the responses that hasnt been written before. The mechanics of anchoring are the mechanics of anchoring.
I have long held the view that forums are often used by contributors to simply post their opinions regardless of what has gone before6 - either historically or within a few posts on the thread. Hence the high levels of repetition and little evidence of use of the search facilty.
My own use tends to be mostly flippant unless I am wrestling with a technical challenge when I do seek learned opinion.
I also think that most questions are answered within the first few posts and much of what follows is chatter. When i have my answer I tend to say thank you as a means of shutting down the thread. It sometimes works.
Well - reading back, what an arsey shit I sound?
Anyway - i am truly sorry that your New Year celebrations are held at such an inconvenient time - this does feel unreasonable as I sit here in temperatures outside of -3.
I'll write to the fat blonde in No 10 if you like. I'm sure he will make the necessary arrangements for you whilst he secures his next world beating trade deal with with Australia.

 

[Neeves]

Please do not distract your Honourable PM at least until he has Covid to sorted out.

In the meantime please go out and buy some Oz wine - or considering the temperature, Bundaberg Rum. With China fiddling with out imports we need all the support we can get. I sincerely hope that when you went First Footing you carried a sack of Oz coal with the Black Bun!

PS. I'll stop wingeing about our weather and unpack the foul weather gear, the rain will wash it.

-3 does sound a bit bracing.

Jonathan

And yes - this is definitely chatter!