When you spend as much time walking around marinas as I do, you find yourself looking at a lot of anchors! An interesting observation is the ever increasing popularity of the ‘new breed’ of anchor designs _ I’m referring to the spade and roll-bar styles. Once choosing an anchor was simple, you were either a CQR man or a Danforth man – or if you were serious, you probably had both at your disposal for varying seabed situations.
So how do you choose an anchor?
Are you looking for a light, simple to use and stow anchor for day trips, or something more substantial that gives you a worry free sleep – probably both!
It seems just about every boating publication or internet site has published an anchor test over the years, and most results are controversial and notoriously subjective. There are so many variables when testing, including wind shifts, swell, currents, seabed conditions and whether your rode is all chain or a rope/chain combination. Having said that, some of these tests are a good starting point when updating your anchor gear, and there are some consistently strong performers amongst the new designs.
However, with so many designs to choose from, it doesn’t hurt to seek professional advice before upgrading. When we upgrade a client’s ground tackle we look at a variety of criteria including how and where they use their boat, anchorages used regularly, stowage limitations, and of course the boat’s weight, windage and rode type are critical. This helps us recommend the ideal anchor style and rode combination. It is important to get it right because tests show that a 10 metre yacht, in storm force winds (48 -63 knots), can experience loadings in excess of 3,000kg on their anchor equipment!
Anchor Rode
As mentioned, a good anchor is only part of the equation. Your rode, which is the chain or chain/rope combination, is equally as important. Some old timers say if you have enough rode out then it shouldn’t matter what anchor you use! Many experienced cruisers argue a chain and rope combination is best for storm conditions. The theory is the stretch in a good nylon rope can help shock absorb some of the extreme pressure that might break an anchor out of the seabed. However, all chain rode has the added advantage of extra weight. The weight not only helps keep the angle of the anchors shank flat, but the sag in the chain acts as the shock absorber. For me, the heavier gauge chain you can carry, the better. So just like the anchor, rode selection isn’t always straight forward, and a lot of the time, the decision will often come down to a compromise of how much weight you want to carry in the bow. One good tip I have learnt is always carry a quality set of bolt cutters capable of cutting your chain in an emergency.
Snubbers
One down side to having all chain is the lack of stretch if it does come tight, especially on a shorter scope. It is generally recommended you use a ‘snubber’ which is a simple bridle of nylon rope attached to a chain link and fastened on cleats. This acts as a shock absorber and also takes the weight off the winch gypsy. The other benefit is the elimination of noise made by the chain grinding and clunking when the boat swings. There are many ‘chain grab’ fittings available but recently I came across a beautifully designed one that is easily attached or removed from taut chain. They come in custom sizes designed to spread the load evenly over the chain link to avoid weakening or stretching the link.
Anchor Scope
For me, one of the main criteria for successful anchoring is how much scope you use. Scope is the ratio of rode to the depth of water. Most agree a minimum safe scope ratio is 5:1. To calculate this, simply measure the depth of water and multiply by 5. For example, if you are in approximately 6 metres of water, you need 6 x 5 = 30 metres of rode. Obviously in tight anchorages, and day trips you may use as little as 3:1, but be on the alert as anchors do drag easily with such short rode. In storm conditions it is recommended you significantly increase scope to 10:1 or more! It’s really a matter of common sense, and as the old timers say; chain is of little use sitting in the locker, get it out, and then when it really starts to blow during the night, just pull another blanket over!
This reminds me of a situation I experienced in the early 1980’s when an ‘east coast low’ formed off Cape Moreton. We were anchored behind the Tangalooma Wrecks with our family boats, a 74ft cruiser and 32ft game boat moored alongside. What started as a calm but drizzly morning, quickly deteriorated, and by early afternoon we had a solid 35 knots of SSW with gusts increasing to over 45 knots, and even more frightening, a fast falling barometer! By night fall, our wind gauge needle was hard against the maximum reading of 60 knots! Apart from losing our tender when the tow eye tore out, leaving a plate size chunk of alloy on the end of the painter, we came through the experience relatively unscathed. Dawn revealed some 20 boats had unfortunately been beached. Most of these boats were victims of anchors dragging. What made matters worst, were boats moving around in the dark trying to reset their anchors and inadvertently fouling their props on other boats anchor rode, and of course the whole thing snowballed.
As the wind really started to howl that afternoon, I can clearly recall my father’s preparations, and the lessons I learnt in seamanship and anchoring have stuck with me. With both his boats at risk, the old man wasn’t taking any chances and decided we needed to reset our anchor gear – this time using maximum chain length, on both anchors! As you can image, at 74 feet South Pacific II has some pretty serious anchor gear. We had over 120 metres of chain out on each anchor, and I can tell you, at the height of the blow, the chain was stretched horizontally! Of course we had the engines idling in neutral all night just incase something let go, and some heavy lines to the wrecks, but having that massive amount of chain out made all the difference. We did not move – even with the added weight and of our gameboat alongside!
For me, the lesson was learnt well, the bigger ‘scope’, the better, especially when she really blows!
The most commonly used anchor styles
Danforth – These have two flat flukes that pivot at the head of the shank and are designed to bury the anchor when under tension. They have excellent holding in firm sand, gravel or mud bottoms. However they are not good in rocky or grassy bottoms where they cannot penetrate. I find then excellent when weight is an issue and as a back up second anchor as they store flat.
Claw or Bruce Anchors – These single fluke anchors allow the boat to swing in a full circle generally without breaking loose. They tend to reset themselves easily and hold well in most bottom conditions. This style of anchor is very popular especially amongst the experienced cruising fraternity which says a lot. They have been around since 1972 and first designed to secure oil rigs to the ocean floor.
Plough Anchors or CQR – The old faithful ploughs were first developed in 1933. They work by digging into the bottom when tension is applied. They are a good all-rounder offer holding power in many different bottom conditions, except really soft bottoms. Ploughs come in fixed or pivoting shank styles. The fixed shanks are known as Delta style, while the pivoting shanks are called CQR style.
The Spade – The spade style anchor was developed in 1999 by a French inventor and was a revolution by pioneering the use of a concave blade. This design uses a wedge shaped ballast chamber to ensure the weight is over the tip for instant penetration. This design has been refined by one manufacturer to include a hollow shank for better weight distribution, the addition of large side wing plates to help avoid breakout during tide or wind changes and a flat pivot surface on the underside to aid in recovery. They have also considered its appearance by producing it in polished stainless and it is a beautiful looking addition to any boat – form and function!
Roll-Bar style – These anchors are designed with a roll-bar that helps them self-right to penetrate the bottom with their sharp fluke tips. Like the spade style, it’s the concave blade area, not the weight, which provides the ultimate holding power. There is one roll-bar manufacturer who uses a convex blade to create a vacuum affect with good results also. Again, roll-bar style anchors are very popular amongst the cruising fraternity and test results are positive.
Conclusion
When looking to upgrade your anchor the choice is wide and everyone has an opinion. As mentioned earlier, ask a professional if you are unsure of what will best suit your circumstances. In general, the new spade and roll-bar designs are a revolution and a walk around the marina will quickly confirm their popularity. Certainly in all the independent tests I have read, these new designs were the consistent high performers, and the best were the ones that self-oriented themselves with an optimum penetrating angle. With the development of these new designs we are getting closer to the ultimate anchor, but I don’t believe we are at a point where serious cruisers will give up carrying a selection of anchors for the varying seabeads conditions they encounter.
