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Anchoring Basics, The Hardware

This article deals with the hardware of anchoring systems. It should be remembered when the boat is at anchor it's security relies on the weakest link in the system, so care should be taken selecting components that match in terms of strength.

The following table gives recommendations for anchor types and weights, with the boat length being in feet, the anchor weights being in pounds, while the chain sizes and rope sizes are in millimetres.

These are average recommendations, and if your boat is particularly heavy for its size or has a lot windage, it may be worth moving up a size. The recommendations here for your main anchor.

The anchor needs to be shackled to the chain with a shackle at least as strong as the chain itself.

There are two theories on anchoring depending on which side of the Atlantic you come from. In America it is the norm to use a short length of chain (3m to 10m) shackled to the anchor, followed by nylon rope. By necessity using rope for anchoring means a much larger swinging circle, as to be secure you may well have to pay out 10 times more than the depths of water you are anchored in. This is so that the anchor can have a horizontal pull on it at all times.

The Rope System

The advantage of this system is its lightness, you are not carrying around hundreds of kilos of chain in the bows of the boat (which doesn't help its handling characteristics).

In Europe and the UK anchoring on rope as opposed to chain is a no-no, and indeed is sometimes considered antisocial. The reason for this is lack of space to anchor in our crowded waters. It only takes one person anchoring on rope in a tight anchorage, where everyone else is anchored on chain to put the cat among the pigeons. The rope anchored boat sails about on its excessive scope, threatening to crash into and alarming, skippers boats anchored nearby.

For speedboats, day boats and other small craft that only ever stop to anchor for lunch etc, even in the UK and Europe, it is considered the norm to use a few metres of chain followed by rope.

For anchoring systems using a lot of rope, there is only one type of material suitable and that is nylon. It has very good stretch characteristics therefore allowing it to absorb shocks which would otherwise have been transmitted to the anchor and possibly jerked it out. Two types of rope construction are commonly used, the normal three strand, and the eight stranded anchorplait rope. The huge advantage of the anchorplait rope, although it is somewhat more expensive, is that it flakes down nicely. Another advantage is that it makes a very good and strong splice directly to the chain, that can be run through anchor windlasses (winches). Three strand rope as a serious tendency to kink, go stiff and unmanageable, and generally be very difficult to handle. It is however cheap.

There are various methods of conecting the chain to a rope, depending on the construction of the rope. Anchorplait can be spliced directly to the chain (as can three strand rope somewhat inelegantly), or an eye splice can be made with stainless steel thimble, and this can be shackled to the chain.

The links provided below show how to go about this:

Chain Splice

http://www.animatedknots.com/chainspliceboating/index.php?LogoImage=LogoGrog.jpg&Website=www.animatedknots.com

Eye Splice

http://www.animatedknots.com/splice/index.php?LogoImage=LogoGrog.jpg&Website=www.animatedknots.com

Anchorplait to chain splice

http://www.jimmygreen.co.uk/technical_info/anchorplait_splicing_guide.htm

Even if you use an all chain system for your main anchoring, the above information will be of much use when designing your Kedge anchoring system.

So how much rope and chain you need ? Depending on the anchor you are using in your rope system, between 3 m and maybe up to 10 m, of appropriately sized chain will be needed to be shackled to the anchor. The chain is there to provide a bit of weight to help get a horizontal pull on the anchor, plus to take the abrasion of the seabed which may chafe the rope. The length of rope you will need at a minimum is 10 times the depths that you anticipate anchoring in. Providing you have  spare rope around the boat of the same strength, your anchor line can be extended by tying pieces together if you have to anchor in deeper water than anticipated.

All Chain System

An all chain anchoring system is considered the norm in Europe and the UK for larger vessels. Obviously there is no point in using Ultra lightweight anchors with an all chain system. The anchor is shackled to the chain, the chain is led on board the boat via a chain roller system or hawsepipe. Generally excess chain is kept below decks, and is paid out through a hole in the deck (which is suitably protected and armoured). Depending on the size of the boat, a winch to wind the chain may be necessary, either powered or manual. When choosing a powered winch it is worth getting one where the chain can be paid out quickly under its own steam, rather than having to be slowly lowered by motor.

Whichever system you use for anchoring you will need a strong point or points to secure the chain or the rope. These need to be very substantial, and often on production boats they are woefully inadequate.

How much chain do you need ?   Much depends on your usage of the boat.. Marina based boats that rarely if ever spend a night at anchor generally don't pay too much attention to their anchoring systems. It is generally accepted that three times the depth of the water you are anchored in is the minimum amount of chain you need to pay out. In sterner conditions more chain will be needed. 30 m used to be considered adequate for boats cruising in shoal waters, and indeed it may be, if it is backed up by another 50 m or so of rope that can be easily and quickly attached to the bitter end of the chain.

For the serious cruiser, who intends to spend many nights at anchor in a variety of conditions and depths, 60 m of chain should be the minimum, with perhaps 100 m as the maximum. As mentioned before this chain is very heavy, and can upset the balance of the boat unless it is fed down as low as possible within the boat... and prererably not right in the bows of the boat.

However you arrange it a method needs to be in place to stop the bitter end of the chain disappearing over the side when you anchor. Attaching it with a very strong lashing to a solid point in the chain locker is good...

Chain or rope, you will need to mark your anchor cable so that you can see how much you are paying out.  Painting a batch of the links  in sequential run colours,  such as red white and blue,  at 10 m intervals is one good way.  This is normally done on the dockside,  and is guaranteed to attract the attention of small boys and dogs who will try their best to get paint all over themselves...

Getting the Anchor Up..

For small boats up to about 25 feet long pulling the anchor up by hand whether chain or rope is not too difficult... especially the boat is driven towards the anchor first. In all cases with anchoring watch your fingers.

For larger vessels an anchor windlass will be required, manual or powered. I saw a good piece of advice once about powered windlasses.... if you're going to get one you will probably get a good reliable piece of kit from Italy. To an Italian the very idea of touching anything as beastly and dirty as an anchor or its chain is absolutely abhorent !  Therefore they go to great lengths to design anchor winches that work reliably... so they never have too face touching the horrid, muddy , smelly, THING.

Windlasses under the brand name of "Quick" are manufactured in Italy, are good value for money and they work... we've had one on our boat for many years, it's never let us down. They are readily available in the UK.

Otherwise a manual winch will have to do.

Whichever winch you use it's important to understand that they are not designed to take the strain of anchoring. Never leave your anchor chain just hanging on the windlass, it places unfair strain.

The normal solution is to have a chain hook and a couple of short pieces of rope leading from it. It hooked around the chain, the ropes are led on board through fairleads, pulled in a bit and cleated off.

The other thing to realise is that the chain MUST be matched to the gypsy on the windlass, so it's worth getting chain and windlass together.

Securing the Anchor.

Securing the anchor for sea... ideally your main anchor should be ready to use very quickly, on the other hand when the boat is bouncing around at sea, the heavy anchor needs to be very well secured. Various methods of trapping it in the bow roller can be devised. The advantage of having it here is that quick deployment is possible, while the disadvantages are weight in totally the wrong spot, the crashing and banging noises when waves hit it, and finally should you lose control of your boat in a Marina.... the protruding anchor makes a good battering ram. I've seen a 25 foot boat ram his protruding anchor straight through the top sides of a 50 footer...

Getting the thing on the foredeck where it can be lashed down solidly into custom-made chocks is very seamamlike... not so good on the old back, and always the danger of getting your fingers caught in the moving pieces (if your anchor has moving pieces).

Small day boats probably just chuck the whole lot in a convenient locker.

One other thing worth considering..

Is  a trip line and anchor buoy.  this is a thin length of sinking line that is attached to the forward part of the anchor ( where there is normally a special attachment point).  This,  apart from marking the position of the anchor when it is underwater,  can be used to help free a fouled anchor.

Finally..a word on Kedge Anchors

A word on kedge anchors. Kedge anchors should be considered as a second anchoring system that match your primary anchoring system in strength and scope. The main thing with the kedge system is that it has to be light enough to deploy from the dinghy, and this means using a short length of chain and a long length of rope.

It is hopeless expecting to lug around a heavy anchor for this job, there are many new designs that have high holding power and very light weight. We have used Fortress anchors for this job with great success... they have their limitations (perhaps more on this later), but kilo for kilo, their holding power cannot be matched in a straight line pull.

We know for a fact that a Fortress weighing less than 3 kg can hold our 5 ton sailing boat in winds of F7 on a sandy bottom. I also know that a Fortress weighing less than 20 kg can hold a 60 tonne fishing boat in winds of up to F9 (the sea was actually smoking). 

Without going on too much, as everybody has their own preferences, I have to say that although expensive Fortresses are pretty well the ideal kedge anchor. Shame we can't get some money for promoting them !

It can never be wrong to keep in reserve a long length of uncut nylon rope (sat 50m ++) that can be added to the kedge (or main) anchor system if needed.

And that that concludes this article on the hardware of anchoring.