Anchoring boats using kellets, sentinels or Anchor Buddy anchor weights dispelling myths on misuses and misconceptions 

Lowering a heavy weight down the anchor line after anchoring gives extra security at anchor and reduces the risk of the anchor dragging. 

Sailing ships did not have a motor, so if caught on a lee shore, pigs of iron were lowered down to increase the catenary of the anchor line. Even the Phoenicians used a ‘catenary stone’ over 2000 years ago. 

Generations of boat owners have instinctively known that a concentrated, heavy weight suspended from the bow and positioned off the seabed, is far more effective than letting out even more warp or chain when it blows. It acts like a lot of extra chain but the forces on the boat have to overcome and lift the whole mass, before exerting any pressure on the anchor. Rocks in sacks, buckets of lead, coiled up chain, dive belts or even second anchors have been shackled to the chain, when the integrity of the holding power of the anchor is in question. 

Would boat owners continue to do this if the principle is ineffective?

'New generation' anchor designs continue to improve the setting and holding capacity. However, no matter what anchor you use, the shank of it still lifts with the 5 points of motion  - pitch, surge, heave and yaw, recognised anchoring expert, Earl Hinz talks about in his book "The Complete Book on Anchoring and Mooring".

Some anchor designers are now convinced they are experts in all things anchoring. They question the effectiveness of using kellets, sentinels and anchor weights and encourage boat owners to use a larger anchor to get a similar effect.

Boatmaster and Yachtmaster courses teach that you must use the correct size anchor for your vessel. You must have at least the length (if not 1.5 times) of the boat in good size chain and anchor with a scope of 5 to 1 in normal anchoring conditions. That is 5 times the depth of water at high tide, plus the distance of the waterline to the bow roller. When it blows, it is recommended that the scope be increased to 7 to 1.

While some vessels have an anchor that is far too small, other boat owners carry huge, oversized anchors, especially when they have had difficulty with anchoring. We believe you should ask the manufacturer of your vessel what size of anchor is right for you and use an anchor weight when you want extra security and comfort on boat when it is blowing hard.
 
Anchoring techniques, which anchor is best and whether to use an anchor weight are topics with equal amounts of harsh critics and most ardent supporters. Discuss these with world cruisers and family boat owners and you will get a different answer from anchor manufacturers, armchair sailors or those who sit behind a computer and work on formulae. It has a lot to do with anchoring experiences and personal opinion. Those who use anchor weights swear by their effectiveness.

Dispelling myths on misuses and misconceptions.
Myth
It is said (in one anchor designer's 'knowledge base') that "anchor weights make little practical impact on the rode when conditions are such that the anchor is likely to be troubled". Misconception.

Why do we let out more warp or chain when it blows? A heavy anchor weight, in a concentrated form, is even more effective than letting out more chain when it blows. The forces on the boat have to overcome and lift it, before any pressure is put on the anchor
"When anchoring in foul ground which we do regularly when scuba diving, we always let a generous amount of chain out, deploy our Anchor Buddy and dive down the anchor chain to check the holding power. Since deploying the Anchor Buddy our observation in a variety of sea conditions, is we have observed NO WEIGHT AT ALL PULLING ON OUR DELTA ANCHOR. With the motion of the boat having to contend with the anchor weight and chain, we have never witnessed our Delta anchor working". Merv Dobbs, Whiting 47ft world cruising yacht.

Myth
It is also said 'the sole use for a kellet is to minimise the swinging circle, but this only applies in light to moderate conditions'.  
Misconception.

Wind gusts, the action of waves and wakes, the boat swinging wildly or sailing around at anchor in any weather, can raise the anchor shank and cause the anchor to dislodge.

Do we disregard the following findings by published experts, in favour of the 'new generation' designers of 2009? 

Charles F Chapman, in his book “Piloting and Seamanship and Small Boat Handling 1961” (regarded at that time as the Boater’s Bible) says "If you have reason to doubt that your main anchor is going to hold in a heavy blow, you can increase its holding power by sending a kellet or sentinel down the anchor line...reduced the maximum anchor load nearly 50%." 

Earl Hinz also says “the function of the kellet is to steepen the initial drop of the rode (warp) and to flatten it out on the sea bottom to decrease the anchor lead angle”.

Tests have shown that the correct size anchor of any reputable design pulled horizontally is more likely to hold than an oversize anchor pulled upwards. 

Here is what the Royal Navy says about anchors dragging 

Anchor designs continue to improve but the shank still lifts with the 5 points of motion Earl Hinz talks about - pitch, surge, heave and yaw.

Again, in his book Earl Hinz says that the wind creates yawing (swinging) and swaying, the waves create pitching and heaving, and the anchor restraint is involved with surging. Surging of the boat sometimes as much as doubles the loads felt from the wind drag alone. A vessel snubs when her bow lifts to a sea and the chain is pulled taut with a jerk. 

When the shank is pulled above horizontal, the efficiency of the anchor is greatly reduced. If the angle of pull is 10 degrees off the seabed, the anchor's maximum holding power is down to 60%. At 15 degrees, it is further reduced to only 40% of its maximum holding power. The additional pull when a ship yaws (swings) is considerable. (Royal Navy Admiralty Manual of Seamanship Vol.2).

We are all aware that it is vital to keep the anchor shank and as much chain as possible, on the seabed. This ensures the pull on the anchor is horizontal, rather than vertical. This is why so many boat owners now prefer all chain anchoring. 

Having an all chain anchoring system can help, but chain spread across the seabed still lifts relatively easily. It is also possible to let out even more chain or rope warp in these situations to increase the catenary, but that results in the boat swinging in a wider arc. Interesting that the all chain Anchor Buddy anchor weight outsells the other models by 4 to 1! Very few cruising boats that head off to the Pacific each year leave without one on board.

Hold your fishing rod and reel by the tip end. This usually light piece of equipment is now quite heavy to lift up. It is simply a matter of leverage. Mathematical formulae prove that the heavier the weight, the more effective it is. Sail Magazine tests have shown on the recommended anchoring scope of 5 to1, it takes a horizontal force of 147lb to lift a 30lb weight off the seabed.

"I dived down to see the Anchor Buddy working. The angle change of the rode induced by the Buddy was significant - I estimated it to be between 20 and 30 degrees. The weight was serving as a spring, absorbing the weight of the boat in the gusts and leaving the critical section of the rode leading to the anchor unmoved. I took the Buddy off and dived back down to see the difference. The length of rode on the bottom was some three metres less, but more importantly, the movement of the rode was more pronounced, as was the movement across the bottom as the boat swung - just the things that are likely to pop an anchor in questionable holding. I WAS SOLD!" Independent gear test by Editor of Boating World magazine  

An anchor weight

• is most effective in deeper water (20-25ft or more) when it starts to blow.

• Changes the angle of pull on the anchor to horizontal rather than vertical when it is blowing. This helps the anchor dig in - giving you extra security and peace of mind. 
• Acts as a spring and reduces the boat’s overall motion while anchored. It also reduces the snubbing each side of the swing in wind gusts and when the bow lifts to the sea and the chain is pulled taut with a jerk. This fore-aft see-saw motion sometimes felt in surge is normally transmitted through to the anchor and can cause it to dislodge. Life on board is also much more comfortable 
• It reduces the swing of the vessel considerably by holding the chain into the mud or sand bottom and creates incredible drag resistance. Boat swing and sailing around the anchor can cause the anchor to roll out and dislodge. This reduced swinging circle is especially beneficial in crowded bays and for high winded vessels. (Ben Hines, the owner of a 75 ton, 50ft, steel Cape Horn trawler says 'it reduces the swing by about 50%')
• It keeps your rope or chain warp almost vertical and out of the way of other boats moving about in the bay, especially at night.
• In strong tidal currents, when the boat lays broadside to the current, an anchor weight keeps the warp far enough down to keep it clear of the boat and the propeller

The alternatives when it is blowing hard and the anchor's holding power is in question...

You can get in the dinghy and set two anchors and hope the wind does not change direction 
or attach and lower your dive belt, a home-made lead weight, bucket of rocks or a heap of chain in a sack...
the principle is exactly the same. These methods all keep maximum chain on the seabed.
But

• do you really want to be in the dinghy or on the bow using spanners and shackles when it is blowing a gale and the boat is pitching and rolling?
• should you really risk using your second anchor in case of further difficulties?

These purpose designed weights can be simply twisted on or off in less than a minute- no tools are required. Speed is really important if you have to move the boat in a hurry.

We have lots of test results -carried out in real situations as well as computer simulations, that prove the effectiveness of an anchor weight. The technical article on John's Boat Stuff website gives all the formulae needed and you can see them here

However, we feel the very best recommendations come from experienced world sailors. Read their letters here. These boat owners are anchoring in many different anchorages and conditions, not simulating them sitting at a computer. They know their anchor weight makes a difference and that gives them invaluable peace of mind.

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Using an anchor weight is a VERY OLD IDEA - the Phoenicians used a 'CATENARY STONE' 2000 years ago!

*Piloting Seamanship and Small Boat Handling by 
Charles F. Chapman

(Copyright 1961 by The Hearst Corporation 572 Madison Avenue, NY)