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DoubleWhisky · 28-04-2014, 02:05

Quote:

Originally Posted by weavis

Do you find single handing your boat quite easy?

By average it is no problem, but in the case of rough conditions I would not consider Med mooring to the quay as safe single handed. Almost always You can have help from the hand on the quay, but You never can be sure if the hand on the quay is connected to the head knowing what to do

On the other hand Beata is really good mate and two handed we are O.K. all the time

And... I do not like single handing...
Sailing is nice for me when shared

**weavis** · 28-04-2014, 02:10

Quote:

Originally Posted by DoubleWhisky

By average it is no problem, but in the case of rough conditions I would not consider Med mooring to the quay as safe singlehanded. Almost always You can have help from the hand on the quay, but You never can be sure if the hand on the quay is connected to the head knowing what to do

On the other hand Beata is really good mate and two handed we are O.K. all the time

And... I do not like single handing...
Sailing is nice for me when shared

Your vessel is quite large. Im not sure if you have all lines running to the helm. I dont look beyond a 36 footer catamaran for single handing and Im sure your vessel would make me anxious. But then Im not as experienced as you.
I like things close and manageable.

DoubleWhisky · 28-04-2014, 02:19

Quote:

Originally Posted by Andrew Troup

The only truly incurable dragging situations I've encountered have been in shallow water.

Except the case when I tried heavily to anchor on flat uncovered rock, similar to the supermarket parking lot (as we found by diving towards stubborn bottom), it is also my experience

DoubleWhisky · 28-04-2014, 02:32

Quote:

Originally Posted by weavis

Your vessel is quite large. Im not sure if you have all lines running to the helm. I dont look beyond a 36 footer catamaran for single handing and Im sure your vessel would make me anxious. But then Im not as experienced as you.
I like things close and manageable.

I forgot!!! I'm always double handed at least... with autopilot

Not all lines are led to the helm, but all (except spi) are led to the cockpit.
All winches are well oversized and primaries, as well as roof mounted winches, are both electrically and hand operated. Main and genoa are on the rollers. So - it is manageable overall

By the way - the boat is course stable, so in settled conditions I can go for a time without autopilot, just with locked wheel - enough time in most cases to do something in the far corner of the cockpit

DoubleWhisky · 28-04-2014, 03:12

Quote:

Originally Posted by noelex 77

Med mooring usually means the anchor is pulled "uphill" which means the anchor shank angle (which is important for holding) will be better than the same scope when anchoring downhill which is usually the case when anchoring normally.

We often somehow tend to assume that the bottom is flat, but it rarely is a case

poiu · 28-04-2014, 04:15

Quote:

Originally Posted by goboatingnow

To ensure catenary and maintain the shank parallel to the sea bed.

Dave

I thought it might be that. I see catenary explained in my old sailing books with pictures of fisherman's anchors on the end of the rode. I wonder how relevant catenary is though. I can understand for comfort under normal conditions it is a good thing as mentioned in Andrew Troup's response, but I like to anchor assuming I will be getting a 50kt squall in the night and at that wind speed my chain has no perceptible catenary at all. There must be some I suppose, but I would expect it to be negligible in strong conditions like that when it matters most.

DoubleWhisky · 28-04-2014, 06:02

Quote:

Originally Posted by poiu

I like to anchor assuming I will be getting a 50kt squall in the night and at that wind speed my chain has no perceptible catenary at all. There must be some I suppose, but I would expect it to be negligible in strong conditions like that when it matters most.

Yes and no, I think.
The worst for the anchor are dynamic forces, deconsolidating the bottom around the anchor.
If You are laying to the anchor in the steady 50 knots of wind, there is no catenary and all You need is enough length of chain to ensure best possible holding.
But when wind is abating, the chain is going down, boat forward and catenary is regained, to serve its purpose at the next blow.

goboatingnow · 28-04-2014, 06:52

one would assume that some catenary however small is still present in all conditions

dave

DoubleWhisky · 28-04-2014, 08:16

Quote:

Originally Posted by weavis

I dont look beyond a 36 footer catamaran for single handing and Im sure your vessel would make me anxious. But then Im not as experienced as you.

Your friend (with Princess) didn't need to file the insurance claim.
It is, what counts the most

**weavis** · 28-04-2014, 09:20

Quote:

Originally Posted by DoubleWhisky

Your friend (with Princess) didn't need to file the insurance claim.
It is, what counts the most

You have NO idea how throwing them engines in reverse works so good!

Andrew Troup · 28-04-2014, 12:31

Quote:

Originally Posted by DoubleWhisky

Yes and no, I think.
The worst for the anchor are dynamic forces, deconsolidating the bottom around the anchor.
If You are laying to the anchor in the steady 50 knots of wind, there is no catenary and all You need is enough length of chain to ensure best possible holding.
But when wind is abating, the chain is going down, boat forward and catenary is regained, to serve its purpose at the next blow.

Tomasz is revealing a rare degree of discrimination here

(fancy word for being able to reliably sort sheep from goats, Tomasz ...
NOT, in this context, about judging them on the colour of their wool ....)

Most lay people and many self-styled experts on anchoring lump two different aspects of catenary together, and dismiss the whole concept because one of them is invalidated (in their view) in strong winds.

The "invalidated" aspect is up-angle of the pull on the shank. Most small boats will not be interested in carrying heavy enough chain to assist measurably with this. This is true in all but the deepest anchorages, where chain weight STILL makes a major difference to up-angle at the shank.

The "baby thrown out with the bathwater" is the aspect Tomasz refers to.

As I'm about to (at long last!) explain in the BiB2 thread, it is not exceeding their LOAD limit which breaks anchor chains; it's exceeding their ENERGY limit.

Straightening the catenary of a heavy length of chain converts moving energy coming down the chain from the boat to static gravitational potential energy, in a very efficient process. By the time the chain is straight, it has DONE its work, in this respect.

And the boat cannot acquire more "moving energy" (kinetic energy) from the environment while the chain is straight. So even if the chain stays straight for minutes at a time, that's not a problem. Static loads do not break anchor chains, or pull bollards off decks, and dynamic loads require a run-up.

It's been embarassing and frustrating, in the last decade, to see increasing numbers of smart people repeatedly spreading the mantra "Catenary is of NO value, because any chain will go straight, given strong enough gusts".

This misinformation spread out from a very small number of ambitious, intelligent and influential lay people who are extremely knowledgeable, but seem to have limited appreciation of some of the boundaries of their knowledge. And, at least in some cases, problems around impartiality.

**noelex 77** · 28-04-2014, 14:09

Quote:

Originally Posted by Andrew Troup

It's been embarassing and frustrating, in the last decade, to see increasing numbers of smart people repeatedly spreading the mantra "Catenary is of NO value, because any chain will go straight, given strong enough gusts".

The biggest problem with using larger chain in an effort to decrease the risk of dragging is that it very inefficient.
Catenary is not of "no value", but rather the gains do not make the most efficient use of resources, particularly bow weight.

The ideal cruising boat has the anchor locker a long way from the bow. Your idea of using chain weight to double as ballast is a a good one (used by Boreal and Garcia) or having the chain locker a long way from the bow like a very small number of custom cruising boats. In this case chain weight is much further back (and lower) than anchor weight,making larger chain sensible.

The reality is that 95% of monohull boats have the chain weight at the bow and chain weight is almost as much of penalty as anchor weight.

If we assume a typical cruising boat with the chain locker at the bow, the weight penalty of of going for heavy chain to increase catenary is just too great.

Let's assume a 45 foot cruising boat as an example.

A typical set up would be 80m of chain. If we want to emphasise chain weight we might go with 12mm or even 14mm chain instead of the more common 10mm. Let's examine the consequences.
80m of 10mm weighs 184 kg
80m of 12mm weighs 304kg
80m of 14mm weighs 362kg

If we consider an average 30kg anchor. Instead of using a 14mm chain with a 30kg anchor we could use 10mm chain and a 208kg! anchor for the same weight.
Instead of a 30kg anchor anchor and 12mm chain we could substitute a 150kg anchor for the same total weight.

These anchor weights are way over the top, but they illustrate the inefficiency of putting the weight into chain to maximise holding.

This sort of analysis has driven the desire the maximise the anchor weight and reduce the rode weight. As long as the rode strength is adequate I think its sound policy.

Andrew Troup · 28-04-2014, 20:30

Noelex, you misunderstand my thrust, which in this instance is not about 'reducing the risk of dragging'.

it's about reducing reliance on snubbers, and (in the 0.01% circumstance) avoidance of the possibility that snubbing will break the chain.

I'm not personally comfortable with reliance on resilient snubbers.

They're useful to improve comfort, peace of mind, and wear and tear, but I don't personally care for pushing to the point where they're strictly indispensable, where snubber failure could mean immediate chain failure.

ON EDIT:
This is clearly not an issue for 10mm chain in the example you posit, but people are talking of going to 8mm and even 6mm chains for 45' boats.

They are reasoning on the "Liberace" principle, it seems to me, that "too much of a good thing is precisely the right amount".