Oh, No, Another Thread About Anchoring!

[Stemar]

I set up my anchor rode with cable ties to tell me how much I have out. There's 10m of chain and 50m of octoplait. As it's a cat, and inclined to wander on a single line, I'd like to use a bridle, but what's the best way to attach the bridle to the octoplait?

 

[Neeves]

There is no 'best' way, its what suits you and your crew.

Prussic knot, rolling hitches

more chain (and then a hook or bridle plate), the size smaller than your 10m (which, in common with many, is probably too big). Mixed rodes are commonly based on a mix of cordage and chain of similar UTS, they are your ultimate fall back. Because the cordage is 'hefty' (to equal the strength of the chain) you lose some of the advantage of elasticity (the snubbing effect). Better a longer bit of smaller chain and a longer, thinner thus elastic snubber/bridle.

You will have the joy of being able to access locations to anchor denied keeled yachts - this does not mean you need anchor in more shallow water - but it might be more sheltered (allowing different scope ratios to a keeled yacht). It can take some time to make the transition. Think if you do take the bottom - your accomodation will not fall over

A bridle will not stop you wandering about in an anchorage subject to light fluky winds, but this is true of any yacht. More chain, more friction on the seabed, will tame some of the need for your cat to explore the anchorage. If you are subject to light fluky winds then the cordage will be wearing on the seabed. Chain is easier to keep clean, think mud, than cordage.

If you have a windlass, or ambitions toward a windlass - chain is more easily managed than cordage.

Cordage will be lighter - a major consideration in a cat - not forgetting the limitations to the size of a wallet.

There is no single correct answer.

Jonathan

 

[Stemar]

Thanks Jonathan. I can always rely on you for cat/anchoring stuff!

Prussic knot looks easy to remember - I just can't get a rolling hitch to stay in my head. It's nothing to do with being senile - unless I got that way in my teens ( ), it just never would go in. We should get some elasticity from the octoplait as our rode is fairly light for our relatively heavy cat, but we have no expectation of sitting out a storm as we're unlikely to be more than a couple of hours from a safe haven

We had a bilge keeler before, so are no strangers to anchoring in shallow water nor drying out.

We do have a windlass and the chain is, indeed, too heavy for the boat. Ideally, I'd go with all chain, at least G70, in as small a size as practicable, for the weight, but the wallet is already feeling more than a little stressed, so I've got what I can. At least the gypsy we have does grab the chain, even if I am going to have to feed it into the anchor locker by hand, as the locker is so shallow.

 

[Neeves]

Steve,

It is always difficult to offer advice on forum as there are usually lots of options and all of them can be correct. The one thing none of us ever know are the financial priorities.

I once met someone who had had difficulty anchoring and providing all we spectators with entertainment. I did speak to him and he told me, this was about 10 years ago, 'but its a new anchor, I've just bought it'. It was a copy CQR. I do despair - if I'd known him I would have said consider a Rocna, Supreme, Excel etc etc - but he bought the copy CQR (I also had had one, which I retired) because everyone else had one! The copy CQR and Supreme are similarly priced here, both available from our biggest chandlery chain.

So ....some of my advice is - for the future, for others to read and mull over (before they commit funds). Its also why my posts are so long and repetitive.


But going back to the thread. Knots are less well accepted by others - one day it might not be you deploying the anchor - so if there is a knot that is easy (and works) adopt it. Its also why I like chain, chain hooks can be applied by a novice, or a grandaughter (with a skippers watch full eye) - knots are more of a challenge.

It depends how over sized your chain might be but with a good snubber (or bridle that is designed to also be a snubber) you will never breach the WLL of even the smallest G30 chain for your, or my, cat. Its hard to accept that something so skinny is safe, especially if the original chain was so big. Just consider the lifting industry have replaced G30 with a G100 - and chain breakage in the lifting industry nor in use as leisure anchors (where some use G70) is ever mentioned. Anchor chain if used correctly - is safe. Anchors drag, anchors bend, chain hooks fail, shackles fail (or come undone) - but chain failure is a thing of the past.

In terms of small lockers

This is 50m of G30 8mm chain, in the rear two pails and 75m of High Tensile 6mm chain in the front 2 pails. We saved some weight and also increased the length of the rode. In 10 years we have never deployed more than 40m of the 6mm (but we do have a 30m bridle (30m x 10mm each arm). We paint marked the 6mm and have cable ties. The paint wears off the 'outside' of the links but is retained on the 'inside'. The biggest issue with down sizing chain is getting compatible connectors that are strong enough and fit both chain and anchor - when you are ready ask me (start a new thread and or send me a 'warning' PM). Your anchor will be sized for the next size up chain, 8mm, say needing 3/8th" shackle but the chain will be too small, 6mm, for the clevis pin.


Jonathan

 

[Neeves]

Steve,

I don't know your anchor/chain locker this might thus be totally irrelevant

To allow you to compare, we are 38' x 22'6" beam and weigh in at 7t in full cruising mode (that includes 200l of fuel (+ 100l in cans on deck) and 400l of water, 2 on board plus stores for at least a month, 4 headsails, 2 kayaks etc etc. We work out to have a similar windage to a Bav 45 - strip out the Bav's keel and the 2 yachts are a similar dry weight (mostly fibreglass).

Our chain locker is 'in' the forward section of the bridge deck and just ahead of the mast. The locker is shallow and holds the windlass, the top of which is under the deck. The locker is voluminous but shallow. It slopes slightly aft and has 1" drain holes at the two 'bottom' corners.

To air and drain the chain we have installed some cheap rubber door mats that have big perforations to allow drainage and airing and pimples on the underside that allows the seawater to drain away. You have a lot of rope - it is best, if you can, to retreive the rope and store in a way that it is not in contact with the chain. The rope will hold water and is a recipe for chain corrosion. The ideal is to hang it up to dry - but you mentioned your locker is shallow - so this might not be possible.

The picture illustrates our newly painted (and installed) chain. One day I'll take another picture - to show the loss of the paint.



I thought to include this graph. Catenary and elasticity are about managing snatch loads and, load the rode up and the catenary straightens and/or the rope stretches. Stretch the rope, straighten the catenary and you store the energy developed by the moving yacht (as it yaws and moves back and forward) - you can measure and/or calculate the stored energy in Joules for both catenary and nylon (so a direct comparison).

This graph simply compares 10m of 10mm nylon and 30m of 10mm chain with the chain deployed at a 5:1 scope. Don't think of nylon in terms of diameter - but in weight per meter (so its volume rather than diameter).

Upto about 300kg of tension both materials offer a similar ability to accept snatch loads. Beyond 300kg nylon out performs chain. You could of course deploy more chain.

300kg of tension is roughly 30 knots of wind, maybe 35 knots for your cat - so really at the extremes you are ever likely to endure.

Note that it is a very wimpy rope - it does not have the strength of the chain - so not to be used for the rode but excellent as a snubber. You don't need much rope to provide the same performance as a lot of heavy chain. The reality is that in practice, using chain and a snubber (or bridle) the two components work together - its not one or the other. My thought would be - your rope portion of the actual rode will provide less elasticity than you think - its beefy (much bigger than the 10mm here). Make your bridle up from 8mm or 10mm nylon (I'd use 8mm - but you might be twitchy about something so thin). I'd make each arm at least 10m long. Snubbers are a consumable, like your sails, they wear (life is a function of stretch cycles and intensity). Have spares, which might be mooring lines.

Longer term you can amend, smaller chain, longer snubbers, as you grow more confident in the kit.

What you have currently (except you don't seem to have a bridle) is fine - spend the extra money when you test things out.



Jonathan