Ok guys, anchors question

[Cheechako]

I want an anchor that fits the boat/bow/roller etc well. Inside that parameter I want it larger than normal maker recommendations, but not overly large.
On my 47 footer I bought an 88# anchor. The choice was 55# or 88# in the maker's line. Got it to the boat and realized it's just too darn big. Took it back and settled for the 55 pounder. It worked fine.

[noelex 77]

For most cruising boats the weight in the anchor is insignificant compared to the weight in the chain.

If you Increase the anchor size by say 30%, you gain around 30% in holding capacity, but the total ground tackle weight only increases by around 3% (for example with 80m of 10mm chain and a 20kg anchor).

A larger anchor is effectively a “bargain”. It conveys significant extra capability for a very modest weight penalty.

[Panope]

Originally Posted by Mike OReilly

...........The longer I spend on anchor the more I'm convinced that it is a far more complex problem than any simple test, calculator, or manufacture's recommendation can cover. There are simply too many variables, all of which interact with each other differently, at different rates, in different ways. ...........

Exactly.

I have been asked countless times about what size anchor someone should buy. Even after asking many personal question, I can never really give a definite answer.

If I were to become an anchor manufacturer (and one day I might) I would absolutely not publish an anchor sizing chart.

Steve

[boatpoker]

Our 38' is 20,000lb.
55llb Rocna
We like to sleep.

Get the biggest anchor you can handle.

[thinwater]

Originally Posted by boatpoker

Our 38' is 20,000lb.
55llb Rocna
We like to sleep.

Get the biggest anchor you can handle.

I bought a 34' boat with no roller or windlass (true story).


So what does "biggest I could handle" mean? With a bad back, I could argue that anything over 15 pounds is too much. I cruised a 27' boat with a pair of 7-pound Fortress anchors for thousands of miles, often for weeks at a time. No problems. Sometimes I added a 13-pound Northill for weeds. I could have installed a roller and windlass suitable for 100 pounds easily. I went with a 35# anchor (all chain and windlass) on the 34' cat and was happy, never feeling it was too small or too big, including some major hail storms and one tropical storm (I set a second anchor for that, but there was no evidence that the bower moved). It was easier to handle than the 7# Fortress.


Ease of handling is about the equipment, not the size of the anchor.

[boatpoker]

Originally Posted by thinwater

I bought a 34' boat with no roller or windlass (true story).


So what does "biggest I could handle" mean? With a bad back, I could argue that anything over 15 pounds is too much. I cruised a 27' boat with a pair of 7-pound Fortress anchors for thousands of miles, often for weeks at a time. No problems. Sometimes I added a 13-pound Northill for weeds. I could have installed a roller and windlass suitable for 100 pounds easily. I went with a 35# anchor (all chain and windlass) on the 34' cat and was happy, never feeling it was too small or too big, including some major hail storms and one tropical storm (I set a second anchor for that, but there was no evidence that the bower moved). It was easier to handle than the 7# Fortress.


Ease of handling is about the equipment, not the size of the anchor.

Not sure what your point is. If you can't handle a bigger anchor don't get one.

[noelex 77]

Originally Posted by thinwater

I bought a 34' boat with no roller or windlass (true story).
So what does "biggest I could handle" mean?

This has been the significant change in recent times.

Modern powerful anchor windlasses enable even a small crew to manage heavy ground tackle with the push of a button. This has the dual benefit of enabling the fitting of large anchors (increasing holding, especially in marginal substrates) and enabling the dead weight of long chain lengths to be be recovered (allowing anchoring at deeper depths).

This, combined with modern anchor technology, has been a revelation in anchoring ability. Anchorages previously deemed “unsuitable” or only viable for “settled conditions” are now perfectly suitable for general use. Many anchorages previously categorised as “poor holding” are no longer a concern with a modern “oversized” anchor.

Not all boats can take full advantage of these improvements. Electric windlasses are not viable on smaller, especially light, cruising boats. In this case the anchoring limitations need to be accepted, but for most there is new world of anchorages and anchor opportunities available, if you fit the right gear.

Don’t fit an anchor size that your boat or crew cannot handle, but don’t try and save a small fraction of the total ground tackle weight accepting an anchor with reduced holding ability when there are better alternatives that open up many previously untenable anchorages.

[MathiasW]

Originally Posted by Mike OReilly

The longer I spend on anchor the more I'm convinced that it is a far more complex problem than any simple test, calculator, or manufacture's recommendation can cover. There are simply too many variables, all of which interact with each other differently, at different rates, in different ways.

IOW, it's a highly complex problem that all these theoretical guides can only approximate. I think of it like weather models. They are great, but they are approximations of reality that often become overwhelmed by the complexity of the real world.

I very much respect your experience when it comes to anchoring and would not dream to challenge you what is best for you and your vessel.

But do you really think that anchoring is such a complex problem that it cannot be reasonably tackled with a scientific approach? And based on that a calculator?

Let's compare that with an aircraft. You would be quite ok to board a plane when the pilot says he does not believe in flight simulators and prefers to gain experience whilst being on the job? I would not think so. And you ditch weather forecasts, as they are wrong, anyway?

Anchoring is a far lesser problem than flying an aircraft or forecasting weather. Orders of magnitude less complex. It has many variables to it, correct, but these variables are not of equal importance. Engineering as well as science is about reducing the complexity of a problem to the point that it is manageable, but still makes reasonable predictions of reality. So, you ignore as many variables as you see fit and then see whether the prediction still makes sense.

Often, you can gain general insights about how some variables affect the situation which remains true even when including many more variables in a more complex system. That is valuable insight that will help you to make a better decision when anchoring, independent of any particular numbers a calculator may spit out. It is a robust result. In your weather model is is how highs and lows behave and move, for instance.

The beauty of such an approach is that it is providing answers for a range of parameters and not just for a single vessel. Generalization is the key word here.

And yes, as an old salty you will be able to go beyond that point and be better at anchoring than somebody just armed with a tool, but new to it all. But the newbie will still be better off than before. For a beginner it is very hard to pick the right answer out of possibly contradicting answers, as is so often found in this forum.

And what is the current benchmark, really, a model of anchoring has to beat in this field? The RYA says 4 times anchor depth, and more if needed. So, just about any reasonable model will be performing better than that.

Science advances in incremental steps, and it is never a good idea to try and prevent these incremental steps by saying it is not perfect. As long as it is better than before, it is progress.

It may not help the old saltie, but it definitely will help the beginner to make less mistakes.

Cheers,

Mathias

anchorchaincalculator.com

[boatpoker]

Good Lord ... unsubscribed.

[thinwater]

Originally Posted by boatpoker

Not sure what your point is. If you can't handle a bigger anchor don't get one.

The point is OBVIOUS.


You can handle any size anchor you install the gear to handle. We're supposed to get the biggest anchor that will fit the factory roller, even if there is either none or it is too small? We're supposed to chose and anchor, good holding or not based on weight, if it is will fit?


The point is that the advice is oversimplified to the point of unusability, like saying "you can't be too safe." Of course you can. We have made the big anchor advice into a slogan.



The thread starter question was a fair one.

[thinwater]

Originally Posted by noelex 77

This has been the significant change in recent times.

Modern powerful anchor windlasses enable even a small crew to manage heavy ground tackle with the push of a button. This has the dual benefit of enabling the fitting of large anchors (increasing holding, especially in marginal substrates) and enabling the dead weight of long chain lengths to be be recovered (allowing anchoring at deeper depths).

This, combined with modern anchor technology, has been a revelation in anchoring ability. Anchorages previously deemed “unsuitable” or only viable for “settled conditions” are now perfectly suitable for general use. Many anchorages previously categorized as “poor holding” are no longer a concern with a modern “oversized” anchor.

Not all boats can take full advantage of these improvements. Electric windlasses are not viable on smaller, especially light, cruising boats. In this case the anchoring limitations need to be accepted, but for most there is new world of anchorages and anchor opportunities available, if you fit the right gear.

Don’t fit an anchor size that your boat or crew cannot handle, but don’t try and save a small fraction of the total ground tackle weight accepting an anchor with reduced holding ability when there are better alternatives that open up many previously untenable anchorages.

Very well said.

[Mike OReilly]

Originally Posted by MathiasW

But do you really think that anchoring is such a complex problem that it cannot be reasonably tackled with a scientific approach? And based on that a calculator?

As most people know, I'm a big proponent of following a scientific approach to almost all questions. I certainly never suggested we can't get better with every iteration of our understanding. Newer anchors are better designed; a direct result of our increasing knowledge and understanding.

But a key feature of the scientific approach is an appreciation of the unknown-unknowns of a problem. So yes, I stand by my statement that anchoring is "a far more complex problem than any simple test, calculator, or manufacture's recommendation can cover."

That doesn't mean tests, calculators and manufacture's recommendations are useless. Most of the time they do approximate reality fairly well, much like our weather models. But they are only an approximation, and simply cannot cover the range of possible interactions.

Tests like Panope's, and calculators like yours, are invaluable resources. But they should always be viewed with a grain of salt.

[s/v Jedi]

Originally Posted by thinwater

The point is OBVIOUS.


You can handle any size anchor you install the gear to handle. We're supposed to get the biggest anchor that will fit the factory roller, even if there is either none or it is too small? We're supposed to chose and anchor, good holding or not based on weight, if it is will fit?


The point is that the advice is oversimplified to the point of unusability, like saying "you can't be too safe." Of course you can. We have made the big anchor advice into a slogan.

The thread starter question was a fair one.

Maybe when a boat doesn’t come with a windlass and not even a bow roller, it isn’t meant to anchor out. I’m serious. Either modify the boat by adding an anchor sprit, roller, chain stopper, windlass and chain locker, or don’t anchor out

[Mike OReilly]

My first cruising boat was a 34' ketch. It came to me without any roller, and certainly no windlass. It came from an area where no one anchored out.

You know what I did? I installed a proper roller (dual), and a way to store the anchors. It's no different than any improvement that one makes on a boat.

[s/v Jedi]

Originally Posted by Mike OReilly

My first cruising boat was a 34' ketch. It came to me without any roller, and certainly no windlass. It came from an area where no one anchored out.

You know what I did? I installed a proper roller (dual), and a way to store the anchors. It's no different than any improvement that one makes on a boat.

Exactly