Only One Anchor

[TAREUA]

For myself, I have never been comfortable with 3:1. That always was a minimum for me, not a target. 'Look for 7:1 but settle for 5:1' I have repeated to myself and anyone nearby many times. Sometimes 3:1 is all there is room for, which makes good tackle set well with a springy snubber of sufficient length all the more crucial. My current boat has a ton of freeboard and can quickly straighten a chain left too short. For sleeker more low profile boats, less may well be plenty.

[MidLandOne]

Originally Posted by Topazken

There is no caternary effect at 3:1 and 70 knot winds. It has been well proven that depending on windage, at 50 knots plus the chain will become taut with a 3:1 scope.

What you are missing by that generalisation (and which I alluded to by reference to non use of short scope in shallow water at the end of my post) is that the force to pull the catenary near straight (it actually requires an infinite force to pull a catenary dead straight so is impossible) is dependant on its length and the depth in the catenary. Both the length and the depth of the catenary increase as the depth of water anchored in is increased for the same scope ratio.

That is, it is very much harder to pull an all chain cable catenary near straight with a 3:1 scope in 20m of water than it is with 3:1 scope in 2m of water. So it is not correct to make generalisations such as you have done. One can make do with much smaller scope ratios in deep water than one can in very shallow water and knowledgable sailors take that into account (as well as the other considerations I mentioned in my post).

Of course chain weight comes into it also.

[Topazken]

Well, what is pretty clear is that most of the visitors and posters are not that knowlegeable. They are like we all were in the beginning, just trying to figure it all out. The further one gets from the home port, the more everyone seems to know.

As for the caternary, you need the chain near the anchor to be either on the ground or as close to parallel as possible. This is what sets up the anchor angle properly so it will continue to dig in. As soon as the chain starts coming off the bottom, the anchor starts to get pulled out.

This brings me back you my intitial point. Using a lot of scope is a better starting point than less. Yes, most times 3:1 can be okay. Used every day and in all conditions, you will run a good chance of losing your boat, or at least a serious grounding.

A dragging boat will almost always get pulled into deeper water (when world cruising) this only magnifies the problem of shorter scope.

If asked by a beginner whether they should use 3:1 or 5:1, I will always suggest more scope.

My original post was really just a recipe for near guaranteed success. Because of my circumnavigation and exploration while writing my cruising guides, I anchored more times and in more places and in more situations than just about anyone. The difference between 3:1 and 5:1 is just a few more second of windlass button pushing. Why short chain yourself?

[MarkJ]

Originally Posted by Topazken

Well, what is pretty clear is that most of the visitors and posters are not that knowlegeable.

Its just your belittling method of writing, such as this, that I don't find at all helpful.
Its rude and I believe a tad insulting and probably not warranted and certainly won't get more people to want to listen to you.

Mark

[Topazken]

Mark J

I do not intend to belittle anyone. I made it very clear that we all start out not knowing very much. A few on the board have sailed around the world, some have crossed oceans nd some have just done some daysailing. Is t belittling to acknowldge that? i Have never skydived and if an experienced skydiver said I di not have experience I would not feel belittled.. it is simply the truth.

The poll in this thread is a perfect example. It would do not good for me to let all of the people who selected Danforth as the one anchor they would cruise with go unchallenged. You cannot have spent any serious time cruising and think that.

There are plenty of people on this board giving advice without any real experience. They tell things people that are just plain dangerous. There are many different ways to do lots of things and in most cases, many different methods will work. In others, they won't and I feel obligated to point it out.

[Viking Sailor]

Originally Posted by Topazken

Mark J

I do not intend to belittle anyone. I made it very clear that we all start out not knowing very much. A few on the board have sailed around the world, some have crossed oceans nd some have just done some daysailing. Is t belittling to acknowldge that? i Have never skydived and if an experienced skydiver said I di not have experience I would not feel belittled.. it is simply the truth.

The poll in this thread is a perfect example. It would do not good for me to let all of the people who selected Danforth as the one anchor they would cruise with go unchallenged. You cannot have spent any serious time cruising and think that.

There are plenty of people on this board giving advice without any real experience. They tell things people that are just plain dangerous. There are many different ways to do lots of things and in most cases, many different methods will work. In others, they won't and I feel obligated to point it out.

Having lots of experience doesn't necessarily mean that someone know a lot - it could only mean that they were lucky enough to have survived their experiences.

[Alan Wheeler]

I think most of us make a judgement of the conditions of the time, the holding, the depth, the type of gear on the boat and the other dangers around us, and use what is appropriate.

Absolutely. If I was in 70kts of wind, I made one major mistake other than anchoring. I shouldn't be there. OK, so if by some chance I have no option, then yeah sure, anybody in 70knts is going to let out all they have. If I had 10x the depth, it would all be out.
There are several issues to how much you lay out. Firstly is how crowded the anchorage is. Secondly the depth. We have bays here in my home patch that are 90ft of water just 10ft from the beach and it continues to get deeper. So how much do you put out then?? I would like to bet no one has 500 plus ft of chain in their locker. And if the wind changes? then what. You are either on that beach, or in water far to deep to reach even with 2:1. I had to anchor just last week with just a meesly 15ft of chain on the bottom. Everything I had out and only just touching the bottom. Full reverse on the engine would not move us. So was that enough, No actually. The wind changed and blew at 40kts and we dragged. But I was prepared. You see Ken, maybe I haven't sailed in those beautiful Islands and Atolls. But you haven't sailed in my waters obviousely either, SO how does that make you an expert in the anchoring decisions I have to make. Seafox frequents just over the hill from me. He has a whole different anchoring technique to meet the requirements over his way. Over the opposite hill is shallow sandy places. You will be sharing very crowded bays of 60 odd boats all trying to get into a little nook for shelter. You have to think very carefully about scope and where everybody ends up as the wind changes during the day. The wind blows one direction in the morning, turns and blows hard the opposite in the afternoon and then dies to nothing at night. An entirely different set of requirements there, or you are going to have you neighbours boat up your date at some point in the day.
70kts, sheesh, who's going to sleep through 70kts anway.

I have said my piece in anther thread about Kens Attitude, so I am not going there this time.

[Boracay]

Only being a tiny part kiwi I'm guessing that "over the hill" refers to the other side of the South Island (and the other side of a major mountain range).

[Steve Pope]

I think wheels means literally in the next inlet which is just over the hill. Now I'm putting words in wheels mouth, I hope I guessed right. Of course what wheels doesn't say is when all the hoi polloi have returned to their marinas in Wellywood or Nelson etc that all the moorings that have been put throughout the sounds by the local yacht clubs are available again so he won't have to anchor in 100' of water again for a while. And with that beautiful stainless anchor (Dairy Co surplus?) he wouldn't drag anyway

[MarkJ]

Originally Posted by Alan Wheeler

And if the wind changes? then what. .

As far as I can see if you have 70kts then the wind will change as you are so close to the core of whatever type of cell it is (disclaimer if you are in the antarctic).

Now, for many weird reasons, I have never been anchored in a high wind where we needed to stay at anchor, nor been in one where we have had to prepare for a high wind at anchor. So my problem is that I've read books about, and thought through, various senarios that I just can't see working - This is book knowledge where it doesnt work in real life

Take a storm which is approaching so you go into this configuration:

From Boating Made Simple! "Surviving a Storm"

That is fine if the wind is coming from the direction of the big fat arrow. But when the wind clocks around I am in deep trouble as I go from 3 anchors to just 1, and that 1 (the east or west) was probably my kedge!
So I have one dragging and two laid over each other!?

If then, after a period of slow dragging as I can't get the inflatable launched to reset, the wind clocks around more and I have 3 anchors all on top of each other.

So maybe its not the only one anchor thats important, its the chucking out of the 2 cheapies that matters?

Mark

[Alan Wheeler]

I think wheels means literally in the next inlet which is just over the hill. Now I'm putting words in wheels mouth, I hope I guessed right

Yep Steve, You've got it. And yes our club has around 60+ mooring scattered around for that very reason.
I have learn't one interesting point from Darryl(SeaFox) He spent a great deal of his early boating life in Auckland, and so he nearly always uses his anchor. He drops out everything he has, and slleps real well. Interestingly he does not sleep well when coupled to a 5 tonne mooring block. Ont eh other hand, I have spent most of my "big boat at least" life in the sounds. So I sleep real well on the mooring. If I had the choice of the mooring or Anchor, it would be mooring everytime. Providing it is a known mooring like our club ones. A private one I will not touch as I don't know what is down there and what condition it is in.

Mark, your diagram (how'd you do that?) is slightly incorrect. The correct way to do this for a storm, especially for one that is cyclic, is to have the three anchors in an egual angle Y shape. The centre of the rode that connects the three together then becomes the connection point for you rode upto the boat. The boat then swings around that centre point. It is called a Burmudian(spell?) moor. The only issue with this system is in the case that in the first wind direction blow, the anchors are dragged and then as the wind swings, they may tangle. It is remote, but can happen. However, if they drag, they tend to all come into the pull and add the weight of three anchors. If that doesn't stop you, nothing will.

[Factor]

Coupla things

for multi hulls a bridle is absolutely necessary for any overnight or area of concern anchoring, each arm should be roughly the beam. Also the bridle and rode should be of a decent size nylon, but not too thick as you loose some of the key benefit of elasticity. An all chain rode has no place on a multi. But for reasons mentioned above a measure of chain to allow straight pull (and deal with chafe) is necessary.

On scope, there have been a number of tests that I have read that measured load developed on differing scopes and the results were intriguing, the scope had a lot less impact than the weight of the anchor - I will try and dig up the test.

On the issue of the bruce, I have nothing against it at all - indeed have had one and would have another, but to suggest that because they anchor oil rigs with them somehow equates to boats is a little flawed, last time I checked oil rigs dont swing around the anchor with wind and tide.

[MidLandOne]

Originally Posted by Alan Wheeler

...and so he nearly always uses his anchor. He drops out everything he has, and slleps real well. Interestingly he does not sleep well when coupled to a 5 tonne mooring block.

I am the same and in fact have never used any of the moorings in the Sounds (not that we are members of any of the clubs ) and sleep well unless it is really blowing. But I always have the GPS anchor alarm set.

In our case, dropping everything we have normally connected up, that being 75m of chain, in often over 20m of water plus freeboard means a scope - whoops won't mention it as I'm apparantly a learner in this boaty type stuff .

[Alan Wheeler]

but to suggest that because they anchor oil rigs with them somehow equates to boats is a little flawed,

I do agree with you. But I don't htink anyone has equated that. Those rig anchors are huge. We are talking so big that a large Tug can only carry one. A sad story just last year occured. A tug taking an anchor out to drop, had the load come on in an incorrect way and the Anchor rolled the Tug over. The Tug Captain had his young son with him for the ride. His son drowned.

[TAREUA]

I'm not anything like an engineer, and I don't have any hidden agenda other than curiosity: Weight vs. Setting in anchor effectiveness? Some of the newer anchors manufacturers seem to recommend lighter weights of anchor than with older traditional anchors. The reason being that lateral pull on a set anchor depends on its ability to dig down and not on its weight. It would seem to me that if you are often in situations that require shorter scope, you should have a heavier anchor as more of the holding will come from weight than from set.
Also, I have seen some test results that show the Hydrobubble anchor getting high marks, but I have never even seen one on a boat. Anyone have experience with them or with the XYZ?
-Casey