It is designed to dig into the bottom like a shovel, and dig deeper as more pressure is applied. The common challenge with all the scoop type anchors is that they set so well, they can be difficult to weigh. Bügelanker, or Wasi: This German-designed bow anchor has a sharp tip for penetrating weed, and features a roll-bar which allows the correct setting attitude to be achieved without the need for extra weight to be inserted into the tip. Spade: This is a French design which has proved successful since 1996. It features a demountable shank (hollow in some instances) and the choice of galvanized steel, stainless steel, or aluminium construction, which means a lighter and more easily stowable anchor. The geometry also makes this anchor self stowing on a single roller. Rocna: This New Zealand spade design, available in galvanised or stainless steel, has been produced since 2004. It has a roll-bar (similar to that of the Bügel), a large spade-like fluke area, and a sharp toe for penetrating weed and grass. The Rocna sets quickly and holds well. Mantus: This is claimed to be a fast setting anchor with high holding power. It is designed as an all round anchor capable of setting even in challenging bottoms such as hard sand/clay bottoms and grass. The shank is made out of a high tensile steel capable of withstanding high loads. It is similar in design to the Rocna but has a larger and wider roll-bar that reduces the risk of fouling and increases the angle of the fluke which results in improved penetration in some bottoms. Ultra: This is an innovative spade design that dispenses with a roll-bar. Made primarily of stainless steel, its main arm is hollow, while the fluke tip has lead within it. It is very similar in appearance to the Spade anchor. Vulcan: A recent sibling to the Rocna, this anchor performs similarly but does not have a roll-bar. Instead the Vulcan has patented design features such as the "V-bulb" and the "Roll Palm" that allow it to dig in deeply. The Vulcan was designed primarily for sailors who had difficulties accommodating the roll-bar Rocna on their bow. Peter Smith (originator of the Rocna) designed it specifically for larger powerboats. Both Vulcans and Rocnas are available in galvanised steel, or in stainless steel. The Vulcan is very similar in appearance to the Spade anchor. Knox