Why Use an Active Anchor!
Ground problems
Because most marine anchors are lost on reefs and rock, the big fear on a hard seabed is an anchor not releasing. On mud and soft ground, drift and anchor drag are the concern. On weed, gravel and hard packed sand, most anchors simply don’t bite in. As a result, many vessels have multiple anchors for different types of seabed.
Anchors are generally defined as reef, sand or mud anchors. Therefore, at present no anchor is seen to have a broad application. The perception is you must have an anchor tailored to the seabed. The problem is, from the surface you can’t be sure what type of seabed you’re on. To anchor safely however, you need to make the right choice.
The problem with anchors
There have been about six basic groups of anchors invented throughout history.
1. Admiralty anchors
2. Double fluke – stock anchors
3. Reef picks and grapple anchors
4. Danforth type sand anchors.
5. Bruce or claw anchors.
6. Plough Anchors – single fluke; convex or concave.
In general, when vessels anchor over rock, they use a reef pick or grapple anchor. When on sand or mud, Danforth twin fluke anchors are thought to be best. Single fluke plough style anchors are often considered to be the best general-purpose all terrain anchors.
Once an anchor choice has been made, the next issue is the anchor rope length (rode length) or chain length. How long should the rode be? How much chain should you have?
One may not even have the luxury to decide, as other boats often need to anchor in the same sheltered space, so you are forced to use a shorter rode than you may want to.
Anchor rode scope (rope or chain length and angle).
As rule of thumb an anchor scope of 7 to 1 is considered ideal. That means that for every one metre of height the bow of the boat is above the sea floor, the boat should have 7 m of rope and chain out to prevent the rode angle (catenary) from going above 12°.
The problem is a 7 to 1 scope often results in a very long rode. If a boat is in 10 m of water, it requires a 70 m rode. This translates into a vessel rotating around in a circle with a diameter of over 130 m, which can be a big problem when many vessels are anchored in a confined space.
Therefore, the only option is to anchor with a shorter rode. As a result, a scope of 5 to 1 is considered acceptable practice. The reality is however, that 5 to 1 is usually a luxury and scopes of 3 to 1 are commonly used in tight anchorages.
Tidal movements can also be a problem, especially in areas where there are big rising tides such as northern Australia or southern UK, as the scope can get a great deal shorter when a tide rises to its highest point.
Assumptions
For these reasons, most vessels have a long chain to keep the shank low to the ground. The problem with using rules of thumb to choose rode length, is that basic geometry is ignored. If the weather deteriorates, there’s no safety factor.
A scope of 5 to 1 for example, has a straight-line pull angle of 11.3° which increases to 12.7° in a 1 metre swell. The best single fluke anchors currently available have a set angle of about 12-15 degrees, which means the anchor will be pulled along like an arrow, cutting through the seabed in soft ground not creating any real drag. The same anchor at a scope of 4 to 1 will simply be pulled from the seabed in heavy conditions.
The best solution
So, what is the best all-round solution? The most versatile anchor in the broadest possible array of environments? An anchor that can hold onto rock, stop you drifting in mud and sand yet still set in weed and gravel. And be retrieved, without the use of a sacrificial pin or plastic ties.
What type of Anchor can you use when you’re not sure what type of ground you are on and need the shortest rode possible, because you don't want to drift into the other boats?
There is only one choice, an Active Anchor!
What is an Active Anchor?
An Active Anchor is a variable pitch, releasable anchor.
The tremendous benefit of these attributes cannot be understated. It’s akin to thinking of driving a car without suspension. It can be done, but now we have good suspension systems, not using them would be considered ludicrous.
Knowledge provides the power to act! Especially when it comes to safety and the sea. Anchors are a must have safety product you may never need to use, but if the one you have doesn’t work when needed, you may never get the chance to use a better one.
Dramatic events aside, all anyone really wants from an anchor is to stay in one spot, and not drift into anything. When moving on, you want to get away easily without needing to cut a rope or pollute the ocean by leaving plastic ties behind.
To put things in perspective, A scope of 3 to 1 has a straight-line angle of 19.5°. That increases to 21.5° with a 1m swell. The profound difference with an Active Anchor is that the articulated stock has at least 15° of extra pitch so there is still a safety factor of at least 6° in a 1 metre swell.
Variable pitch
Why does Variable pitch matter? In short, the axels on a car move up and down to stay in contact with the road. Because without road contact the car has no grip, you can’t stop or apply power. The more power you need to apply, the more contact you need with the road surface. Its why race cars have wide tyres.
How does this relate to marine anchors? In simple terms, in a car you can’t be sure what sort of road you may encounter around the corner, and you can’t change the type of vehicle you are driving halfway through the journey. So, you need one that has the versatility to adapt to the conditions it’s on. On the water, you can’t be sure what type of seabed you’re over. So, you need an anchor that can adapt to the conditions.
Apart from Active Anchors, all anchors have a static pitch of around 15 to 20 degrees, designed to help the anchor set into the ground as quickly as possible. The problem is, a shallow pitch that helps the anchor set, does not create much drag in soft ground, therefore a vessel will not stay in the same position at anchor in mud.
A little-known fact is that the amount of drag created by a flat surface at a pitch of 30 degrees is twice that of the same surface at 15 degrees.
Using this principal, the flukes on an Active Anchor pivot under pressure (going from 20 to 35 degrees) to increase stopping power. The spring-loaded shank then returns the flukes to their normal position like the suspension on a car. This flipper action has the added benefit turning wave action into digging power, harnessing the power of nature and giving a small anchor exceptional holding power.
Yacht anchors with stopper.
As safety is paramount on yachts, on larger double fluke Active Anchors (7 – 14 KG Versions) a stopper can be added to the shank of the anchor by bolting it to the stock ring. This removes any possibility the anchor may release and allows the collar to be positioned to achieve maximum drag in very soft ground or set faster in hard sand and gravel.
Release-ability
Active Anchors can be set to release when the anchor rope is pulled vertically. This is made possible due to a high tensile steel shank and toggle action release mechanism.
The release function has 4 settings from light to lock (no release), however what is not immediately obvious is that the light setting does not greatly reduce the holding power of the anchor in sand, mud or shale. This is because the flukes are held in a relatively static position in soft ground, which pushes the flukes backward toward the rear of the anchor keeping the over centre mechanism in its normal anchoring position.
The release function is most easily triggered on rocky ground, when the fluke tips are the only part of the anchor in a crevice or ledge. Generally speaking, rock is where the ability to release an anchor is needed most.
The release function allows you to anchor with confidence on rocky ground knowing that you can get away with ease and not be concerned about falling overboard trying to pull up the anchor. Active Anchors provide the opportunity to safely retrieve the anchor whilst fishing from small boats, jet skis and kayaks in the more challenging locations where fish tend to be.
How are Active anchors used?
They are used just like any other anchor. But have a collar that can be set in different positions to give the anchor greater stopping power in mud, make it easier to set in sand or made retrievable for reef anchoring.
Releasable settings and “how to reset an active anchor” can be seen here.
Stopper applied collar positions – can be seen here.
More detail about the added benefits of an Active Anchor can be seen here. To sum up – the spring-loaded shank of an Active anchor provides the flexibility to adapt to a vast array of seabeds with a single anchor that's easy to retrieve and outperforms all others.
All anchors in one, superior performance on all ground.
Active Anchors – Embracing the forces of nature!