Anchor Scope

The kind of **** posted on this and other threads like it are why anchorages and harbours are turning into marinas. New boaters are simply too scared to anchor. They are being told its fine to have an old design anchor that only digs in if you know the magic sequence of setting, and then tht they need to put out so much chain that their boat may sink under the weight. I see a correlation here. Perhaps we could go for modern anchors and reasonable scope? Or at the very least could you all prefix your nonsense opinions with "in my opinion"?
 
I have nothing to add on the science and mathematics of it all just what my experience is. I lay out whatever chain seems appropriate using a complex formula that has never been written down and changes dependent on things such as crew and hot beverages. I have 60m of 8mm chain on board attached to my new anchor (Rocna, still too new to appraise). I am currently sitting in 4m of water and have about 25m of chain out. I always use a snubber which I attach at one end to the Sampson post by a spliced loop and the other to the chain by a snap shackle. It has one of those dodgy looking rubber things on it and is 10mm PP (I think). It makes a big difference to chain noise and the boat sits better in a chop. If it was going to blow very hard I would just put out all my chain. You can shackle it together if you don't have the room in an anchorage and then a large loop acts like a chum or angel. If it got really hairy I wonder could you assist with the motor? I have never dragged with my previous anchor (a CQR) despite some pretty bad conditions, hopefully the same will be said of the new one.
 
lustyd said:
The kind of **** posted on this and other threads like it are why anchorages and harbours are turning into marinas. New boaters are simply too scared to anchor. They are being told its fine to have an old design anchor that only digs in if you know the magic sequence of setting, and then tht they need to put out so much chain that their boat may sink under the weight. I see a correlation here. Perhaps we could go for modern anchors and reasonable scope? Or at the very least could you all prefix your nonsense opinions with "in my opinion"?
Click to expand...

In your opinion, what is 'reasonable scope'?
What I see around the coast is mostly a lack of space to use the scope that modern anchor enthusiasts talk about for big winds.
Maybe if Chichester harbour wasn't full of moorings for boats whose owners live in Reading and beyond, there would be space for a few dozen locals to anchor.
But we can't go back to the 1930's.

Also I see a lack of enthusiasm for being on a boat in F8 anchored off, when there is a perfectly nice pontoon in walking distance to a restaurant if you plan adequately.
That looks to be closer to the reality for the majority of amateur yotters, and why not?

Obviously it's different for the few % who sail away from 'civilisation'.
 
Neeves said:
Noelex, think yourself lucky (and discerning), many of us deal with production plastic and the only time we see anything as substantial as that thing is if we take ferry trip! Mind you we do need to improvise - so we can be a wealth of useless information.

Jonathan

I'll try to stop hankering after your samson post and have another bottle of Oz red wine in consolation - but try not to feel homesick - its rained every day for the last 15 in Sydney and I think the total is something like 250mm for the month.
Click to expand...

Australian red is one of few things I miss, so have a glass for me. The European reds are just not the same.
 
lustyd said:
The kind of **** posted on this and other threads like it are why anchorages and harbours are turning into marinas. New boaters are simply too scared to anchor. They are being told its fine to have an old design anchor that only digs in if you know the magic sequence of setting, and then tht they need to put out so much chain that their boat may sink under the weight. I see a correlation here. Perhaps we could go for modern anchors and reasonable scope? Or at the very least could you all prefix your nonsense opinions with "in my opinion"?
Click to expand...

I think you will find if you re-read some of the posts then your assessment is correct. Many are saying, without trying to raise too much controversy - the newer anchors are better. Many are also saying - catenary is not all it is cracked up to be, what you need is a decent anchor (and a snubber). Consequently your statement 'we could go for modern anchors and reasonable scope' is a fair summary.

But if you visit marinas - they are full of yachts with old fashioned anchors, maybe if they took note, bought new anchors - they would then use them (except in F8 when a marina and decent restaurant has considerable attraction!) except when the nearest one is 150nm away?

Jonathan
 
lw395 said:
Yes I would expect wind to be less at deck level.
Which of course is where the majority of the windage is.
I assume you measured this in flat water? So it is wind force not wave force we are talking about.
The number seems high to me, but cats can have a lot of frontal area. And some have a high CD due to those nice patio doors at the back.
On a monohull without a spray hood, the majority of the wind drag often comes from the rig. The hull is in less wind and has a lower CD.
I did some numbers once for my rig, based on the guidelines for antennas, and got much lower forces than 400kg for 40kt of wind.
I also got some big numbers for estimated forces from even modest waves bobbing the bow up and down.
Too many variables as ever, but thanks for putting some proper numbers down.

I feel my policy of anchoring somewhere sheltered remains sound.
Click to expand...

Your policy of anchoring somewhere sheltered is sound and very, very sensible. Its not a competition.

We found that yachts veer, a lot. Consequently we took 100% of side and 100% of full frontal cross sectional area (because that's what we found). The wind veers and the yacht veers, at times the yacht can be broadside to the gust. We are not looking at averages, we are looking at worst case. A Bav 45 has huge topsides, don't believe me? try jumping from the deck onto a marina pontoon of a Bav 45. (Actually don't try it - its a recipe for a broken ankle) Cats might have apparent large surface areas but a cruising cat is generally what you see at a boat show, a cruising Bav has added, dodgers, biminis, davits (with dinghy). (so the Bav 45 windage is an underestimate for a normal cruising vessel.) We ignored the delightful patio doors we have as they are only for downwind work, a sort of see through spinnaker?, as normally they are not subject to wind in an anchorage. Ours is a low CD cat, unlike the Lagoon with its in your face panoramic windows, look at www.lightwaveyachts.com.au The measurements were in flat water, well sheltered from developing seas - but wind, hence the readings.

At a scope of just under 3:1 in 35 knots we had snatch loads of over 650kg - we did not take many reading before we chickened out.

Waves are another dimension, particularly as they are very difficult to measure. We have a plan to look at waves but its a way off.

Jonathan
 
>The kind of **** posted on this and other threads like it are why anchorages and harbours are turning into marinas. New boaters are simply too scared to anchor. They are being told its fine to have an old design anchor that only digs in if you know the magic sequence of setting, and then tht they need to put out so much chain that their boat may sink under the weight. I see a correlation here. Perhaps we could go for modern anchors and reasonable scope? Or at the very least could you all prefix your nonsense opinions with "in my opinion"?

Is that in your opinion? I think that sailors have different experience, different experiences and an opinion on what is they think is right - anchoring, reefing, provisioning, spares to carry, sailing or not in strong winds etc. This gives them an opinion, thus there is no need to say in my opinion, we know it is. And by the way don't be rude (' **** and nonsense opinions') people here will think less of you and rightly so.
 
lustyd said:
The kind of **** posted on this and other threads like it are why anchorages and harbours are turning into marinas. New boaters are simply too scared to anchor. They are being told its fine to have an old design anchor that only digs in if you know the magic sequence of setting, and then tht they need to put out so much chain that their boat may sink under the weight. I see a correlation here. Perhaps we could go for modern anchors and reasonable scope? Or at the very least could you all prefix your nonsense opinions with "in my opinion"?
Click to expand...

In my opinion the growth of marinas is nothing to do with that. It is everything to do with convenience for the boaters and the ability for the operator to cram more boats into limited space than is possible in an anchorage.

Perhaps you should have started your own post off by prefixing it with "in my opinion"?

In my opinion.
 
pmagowan said:
If it got really hairy I wonder could you assist with the motor?
Click to expand...
I think the trouble with using the motor is that you would have to monitor and control it all the time, as if the wind lulls the engine would cause the boat to over ride the anchor chain, then when the wind gusts, the boat would turn broadside!

My solution is to hoist a reefed mizzen, but not all have that option :)
I think the recommended solution is a riding sail hoisted on the backstay.

This is a fancy example:
https://encrypted-tbn0.gstatic.com/...TNNFkZnkRH2I3w6fwoIkuI5UJXcE_tQozkOIPTB3LhoCg
 
Neeves said:
Your policy of anchoring somewhere sheltered is sound and very, very sensible. Its not a competition.

We found that yachts veer, a lot. Consequently we took 100% of side and 100% of full frontal cross sectional area (because that's what we found). The wind veers and the yacht veers, at times the yacht can be broadside to the gust. We are not looking at averages, we are looking at worst case. A Bav 45 has huge topsides, don't believe me? try jumping from the deck onto a marina pontoon of a Bav 45. (Actually don't try it - its a recipe for a broken ankle) Cats might have apparent large surface areas but a cruising cat is generally what you see at a boat show, a cruising Bav has added, dodgers, biminis, davits (with dinghy). (so the Bav 45 windage is an underestimate for a normal cruising vessel.) We ignored the delightful patio doors we have as they are only for downwind work, a sort of see through spinnaker?, as normally they are not subject to wind in an anchorage. Ours is a low CD cat, unlike the Lagoon with its in your face panoramic windows, look at www.lightwaveyachts.com.au The measurements were in flat water, well sheltered from developing seas - but wind, hence the readings.

At a scope of just under 3:1 in 35 knots we had snatch loads of over 650kg - we did not take many reading before we chickened out.

Waves are another dimension, particularly as they are very difficult to measure. We have a plan to look at waves but its a way off.

Jonathan
Click to expand...

Thanks.
My point about patio doors is that the trailing end of an object in a windstream contributes to the drag too. A big blunt immersed transom is slow, perhaps not as slow as a blunt immersed bow. Not an area I could put numbers to though.

I take your point about Bav45's and the like, boats have got bigger, anchors maybe haven't kept up?
My first cruise was on a 23ft boat, the anchors on that were not that small.
 
LadyInBed said:
I think the trouble with using the motor is that you would have to monitor and control it all the time, as if the wind lulls the engine would cause the boat to over ride the anchor chain, then when the wind gusts, the boat would turn broadside!

My solution is to hoist a reefed mizzen, but not all have that option :)
I think the recommended solution is a riding sail hoisted on the backstay.

This is a fancy example:
https://encrypted-tbn0.gstatic.com/...TNNFkZnkRH2I3w6fwoIkuI5UJXcE_tQozkOIPTB3LhoCg
Click to expand...

Yes, probably the motor idea would only be useful for the most extreme conditions were the hellish time at the tiller and controlls would be worth it for riding out a storm on a lee shore with a poorly holding anchor. The sails sound like a good idea but in really bad conditions I think sails can become a handful and sometimes a liability, especially ones that spend 99% of their life in a locker.

For most of us, I suspect, we do a quick mental calculation. This includes variables such as;
Sheltered anchorage
Anchor
Crew an how well fed they are etc
Bottom holding
Wind and sea state
Comfort
Scope
Snubbers
Tide (both range and current)
Etc.

Certainly I think about some or all of these things, and others, but I can't say that my way is right or completely consistent.
 
lw395 said:
Chichester harbour wasn't full of moorings for boats whose owners live in Reading and beyond, there would be space for a few dozen locals to anchor.
Click to expand...

I'm curious how you define "locals"? I lived in Portsmouth for many years, perhaps I should have sold the boat when I left? Besides, mine isn't on a mooring, it's in EYH which was closed off for logging or some such many years before boats were put in there so doesn't count :P
 
pmagowan said:
The sails sound like a good idea but in really bad conditions I think sails can become a handful and sometimes a liability, especially ones that spend 99% of their life in a locker.
Click to expand...

I realised after I had posted that Riding Sail is to stop the boat swinging around, not to give forward drive, but using a mizzen sail will give a little forward drive and helps to stop the boat swinging.
 
I work on the principle that chain in the locker is as usefull as runway behind you.

I rarely put out less than 20m even in good holding in a couple of metres. In fact the first mark on the chain is at 15m. ( 5:1 scope in 2m of water plus the height of the bow roller, 1/2 m under the keel. No point in marking the chain before there is there! ) In up to 10 m all of the chain in the locker goes out, around 70m.

I'm putting a new length of 100m of 10mm and a Rocna on the front which will allow me to set in 15 to 20m of water which is ample for all but the deepest Greek anchorages. More importantly gives me a bit more of scope when backing in 'med style.
 
nimbusgb said:
Easier to look at the water than look for a mark on the chain surely! Rare that one can't see the anchor when it comes off the bottom or at least when it is a metre below the surface! :)
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I go with The Lady. We have a mark at 5m and 1m. Its easier to press a button on the foredeck and watch the bow roller than stretch whilst pressing a button and look over the bow (in the rain with any sea running). Its oddly difficult to see an anchor until it breaks the surface in the dark and not much different in muddy waters.

We also know that we can deploy 30m into an empty chain locker before it towers sufficiently to stop the windlass. We also know that with any chain in the locker we need to knock over 20m towers. So we also mark every 10m.
 
Marks close to the anchor (at say 5 and 10m) are useful in murky water. When the chain comes up tight when breaking out the anchor if the length of chain does not match the depth of water it shows that the chain is caught under a rock.

Often when breaking out my big Rocna it feels like the chain or anchor is hooked onto something totally immovable untill it gradually breaks out of its set. Its reassuring to know at least the chain is not caught.

Of course in the Med, in most of the anchorages, you can see the bottom anyway.
 
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lustyd said:
The kind of **** posted on this and other threads like it are why anchorages and harbours are turning into marinas. New boaters are simply too scared to anchor.
Click to expand...

No comment on the marina part, but I can definitely see the point in your second sentence. Never occurred to me that anchoring was anything to worry about, or at all complicated, until I started reading this forum :)

Pete
 
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