Modern anchors

[mcframe]

A Spade would probably fit.

I have a 15kg, but it has to be stowed in the locker shank first.

I went to http://www.spade-anchor.co.uk/ , clicked on the template links, and printed out two sets of PDFs. Glued them to cardboard, and bought the biggest one that would fit in my anchor locker.

Try:
http://www.spade-anchor.co.uk/Model 60.PDF
http://www.spade-anchor.co.uk/Model 80.PDF
http://www.spade-anchor.co.uk/Model 100.PDF

(And then I got it delivered mail-order from the CI - my postman hates me.)

 

[sighmoon]

Sighmoon has the chain in a separate locker so a Spade would probably fit similar to yours.

Actually, no I don't.

Anyway, thanks all, templates and cardboard seem to be the way to go.

 

[Twister_Ken]

(And then I got it delivered mail-order from the CI - my postman hates me.)

Me too. The postie was somewhat surprised that it had a fragile sticker on it!

 

[rudolph_hart]

Actually, no I don't.

Anyway, thanks all, templates and cardboard seem to be the way to go.

From your photo, she looks like a Dehler (34?).

The last D34 I had came with an aluminium Fortress, plus about 2 fathoms of chain and then warp. Dead easy to handle (light), and all doubts about holding power were dispelled when she rode out a 'mini tornado' (caused building damage locally) while anchored in an Essex creek. She was sheering madly, and coming up short with hefty jerk, then sheering off in the opposite direction, but she didn't drag. Lasted about 20 mins.

The next owner gave it an even more dramatic test off Chichester.

The downside is cost, of course.

 

[sighmoon]

From your photo, she looks like a Dehler (34?)

Dehler, yes. 38

I don't think I'd get a fortress through the space.

 

[KellysEye]

The answer to bad weather is chain, rather than the anchor (our main is a CQR), we carry 280 feet of it. If it's seriously bad weather we have two more anchors to put out each with 100 feet of cahin and 100 feet of rope.

 

[PetiteFleur]

I now have a 25lb Manson to replace my 35lb copy plough anchor - it's still a bit of a wriggle to get it through the pulpit, again I have a secondary ss bar on the pulpit as mentioned. It's possibly a bit on the small side for a Moody33, but so far it's considerable better than the old plough anchor which never seemed to set. The Manson is also lighter and easier to handle than the plough.
Oh, and my Fortress Kedge is also superb! As I'm on a swinging mooring all I have to do is sort out suitable chocks and lashings for securing on deck......

 

[noelex]

The answer to bad weather is chain, rather than the anchor (our main is a CQR), we carry 280 feet of it. If it's seriously bad weather we have two more anchors to put out each with 100 feet of cahin and 100 feet of rope.

Increasing scope increases the anchors holding power up to about 10-14:1 where the law of diminishing returns sets in.
Modern anchoring theory says the weight of the chain does very little. Anyone that doubts this should dive and observe the chain behaviour in strong wind. The chain is effectively a straight line pull.

Put the maximum weight in the anchor and go for the best design.

 

[Poignard]

The chain is effectively a straight line pull.

That suggests there is insufficient chain out.

 

[vyv_cox]

That suggests there is insufficient chain out.

Craig Smith (remember him?) posted photos of his father's boat lying to a huge scope of chain, 100 metres IIRC, in a big blow in Patagonia. The chain was straight, bar tight. I have dived on my anchor in blows in the Med, one in particular in Cala Volpe in Sardinia. Depth of water was only 2 - 2.5 metres, scope was about 35 metres, wind strength up to 40 knots. The whole chain was off the bottom and straight on many occasions and the anchor shank was obviously lifting at times.

People who have calculated such things advise that all catenary is lost, regardless of scope, in winds of force 6 - 7.

 

[Deleted member 36384]

....... People who have calculated such things advise that all catenary is lost .....

Vyv, if I remember correctly, I think at 1:8 scope (depth over anchor:length of chain) is where the angle stops changing by much and any more let out doesn't increase the chances of a horizontal pull on the anchor for any scope that a yacht is likely to carry.

By way of illustration if 1km of chain was laid out the weight would make a difference over that length, but not for they typical lengths that yachts carry.

The main reason for long anchor chains, even if bar tight at times, is that it still offers a degree of damping (in the lulls to gusts) between the yacht and anchor. I doubt it its that much when compared to the force due to windage on the hull in very strong winds.

 

[Poignard]

Craig Smith (remember him?) posted photos of his father's boat lying to a huge scope of chain, 100 metres IIRC, in a big blow in Patagonia. The chain was straight, bar tight. I have dived on my anchor in blows in the Med, one in particular in Cala Volpe in Sardinia. Depth of water was only 2 - 2.5 metres, scope was about 35 metres, wind strength up to 40 knots. The whole chain was off the bottom and straight on many occasions and the anchor shank was obviously lifting at times.

People who have calculated such things advise that all catenary is lost, regardless of scope, in winds of force 6 - 7.

Well I am astonished, but I have the greatest respect for your opinions on all things nautical so I must be in the wrong.

 

[noelex]

That suggests there is insufficient chain out.

More chain helps very little once you get past something like 10-14:1. As Vyv says I seen this effect with lots and lots of scope.

Talk to any boat that has upgraded there anchor, you will find almost universal praise for the extra holding ability. If the chain not the anchor was important there would be no improvement.

 

[NormanS]

Iit depends a lot on the depth. When anchored in really strong wind, I always prefer at least 10m. If you are anchored in any less, in a strong wind, yes you will practically straighten your chain, and will probably get better results with part chain / part nylon. I have all chain, so prefer deeper water if it's going to blow.

 

[sighmoon]

Iit depends a lot on the depth. When anchored in really strong wind, I always prefer at least 10m. If you are anchored in any less, in a strong wind, yes you will practically straighten your chain, and will probably get better results with part chain / part nylon. I have all chain, so prefer deeper water if it's going to blow.

If it's really blowing, I prefer deeper water too, so that I'm further from the shallows in case plan A fails.

 

[Conachair]

Well I am astonished, but I have the greatest respect for your opinions on all things nautical so I must be in the wrong.

There are threads somewhere with the maths behind it, less force than you would instinctivly think and your anchor chain will be off the seabed. Chums won't keep the chain from straightening either once the dynamic forces get up.

 

[Sybarite]

We currently have a genuine 35lb CQR, which in all honesty has been completely fine, but hasn't really been tested in bad weather or poor ground. The 35lb CQR is a bit of a wriggle to get through the pushpit which has a smaller than normal opening*, and is also the biggest anchor that will fit in the anchor locker.

Would a 'next generation' anchor of the same weight fit through the same holes? I'm imagining the flukes would be bigger.

[edit
*a bigger anchor would fit through the hole but need a man stronger than me to get it on and off the roller
- just to add, the current bow fitting isn't the right shape to allow an anchor to stow on the roller]

One anchor which is highly regarded in France and which seems pretty compact is the "Brake".

 

[rotrax]

That suggests there is insufficient chain out.

In the book "All Weather Yachtsman" by Peter Haward, he relates how he and his crew were anchored off Cadiz-IIRC-unable to enter the Med due to the Levanter which was blowing at 160kph in the Straits. When it subsided all the galvanising flaked off the heavy chain which would no longer fit the gypsy as it had stretched very badly. BUT the anchor held. What conclusion can we draw from this? Before anyone jumps in and says it must have been an "X" or "Y" or "Z"-none of these modern style anchors had been thought of then.............

 

[snooks]

What conclusion can we draw from this?

Cheap chain

 

[vyv_cox]

I have to agree with Snooks. Zinc is reasonably ductile and will readily accept deformation of a steel substrate. In one of my previous jobs I used to perform bend tests on galvanised sheet, which consisted of bending it double in the jaws of a vice. If the zinc detached from the steel the sheets were rejected.

Closer to home, this photo shows destructive testing of Grade 30 galvanised chain. No zinc was detached, despite considerable deformation of the links.