The most common anchor in the Fluke Class, for smaller vessels, is the "Llightweight Anchor" (LWT). This anchor is easily recognizable due to the large pivoting fluke areas and the stock being mounted at the crown of the anchor. The most famous of the LWT anchor designs is of course the "Danforth." The "Danforth" name has become synonymous with all lightweight style anchors. So much so, that this entire class of anchors is often referred to as Danforth's regardless of the manufacturer.
The idea behind the Lightweight design was to provide an anchor with good holding characteristics in a small and relatively light weight package that was easy to store aboard a vessel. Richard S. Danforth met this challenge and first tested his original design in 1940.
The design intent was to provide a large fluke surface area relative to the anchor’s weight when compared to other types of anchors. This characteristic of the LWT style anchor provided, when properly set, extremely high holding forces; often to the point where components of the ground tackle system may fail before the anchor drags or breaks out.
The lightweight’s performance, like most modern day anchors, is solely dependent on its ability to dig into the bottom and remain there. During the manufacturing process the fluke angle is critical to provide the best chance for bottom penetration. For your typical sand bottom, that has been found to be ≈32°.
As a testament to this design, since the original patent expired, it has been copied and manufactured by hundreds of companies worldwide in varying degrees of quality.
"Danforth Anchors" The original design of Richard S. Danforth, is now manufactured by Tie Down Engineering.
The Danforth design is well regarded in their ability to provide high holding power in your typical sand or mud bottom. In other bottoms such as grass or kelp, rocks, very hard sand, and clay bottoms they are generally regarded as poor performers due to their inability to penetrate the bottom and set easily.
The use of Hi-Tensile steel in some models, has also provided additional strength in the critical fluke and shank areas.
You can view Comparative Pricing here: Danforth Anchors.
"Fortress Marine Anchors" has taken the LWT anchor design to the next level.
While the Fortress Anchor is almost indistinguishable from the original Danforth to the untrained eye, Fortress Marine has made a number of significant improvements. The Fortress’ fluke angle can be adjusted to match varying bottom conditions, the tripping palms can be modified to assist in setting, and its construction from aluminum-magnesium alloy offers even greater weight savings without sacrificing strength. The Fortress can also be easily disassembled for easy storage if being carried as a second or storm anchor.
Couple all of this with the fact that all Fortress Anchors are Type Certified by the "American Bureau of Shipping" as well as being "DNV-GL" certified as “Super High Holding Power” (SHHP) Anchors (Models FX-85 and FX-125) and you end up with a far superior Lightweight Anchor to most all others on the market."
The Fortress Anchor is available in sizes ranging from 4 pounds (1.8 kg) to 69 pounds (31.3 kg) for all types of vessels up to 150 feet.
You can view Comparative Pricing here: Fortress Marine Anchors.
All anchors will break out given the right conditions, such as during large wind veers or during tidal current changes; the lightweight anchor is no exception in these circumstances.
Another issue of the LWT anchor is when the vessel overrides a partially buried anchor, the anchor line or chain may foul on the exposed portion of the stock preventing the anchor from resetting until cleared.