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Page Title: Llightweight Anchors
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The stockless anchor consists of a heavy head in which the crown, tripping palms, and flukes are forged in one piece. This unit is pivoted on the shank so that it can swing from 45° to either side of the shank. The flukes are large and long, and projecting shoulders or tripping palms are cast at the base of the flukes to make them bite. As the force of the drag exerts itself, the shoulders catch on the bottom and force the anchor to take  hold  by  pushing  the  flukes  downward  into  the bottom. Because an upward pull on the shank of a stockless anchor has a tendency to break out the flukes, a long scope of chain must be used to make sure the shank remains on the bottom when the anchor is set. With too short a scope, or even under a steady pull with a long scope, a stockless anchor may still disengage its flukes as a result of gradually turning over and rolling out. Under this condition, the anchor can offer no resistance  to  dragging  except  by  its  weight. LIGHTWEIGHT ANCHORS Two types of lightweight anchors are used on Navy ships: the Mk 2 LWT and the wedge block LWT anchor. These are shown in views D and F of figure 4-1. Lightweight  anchors  are  constructed  of  compar- atively  light  metal,  but  are  very  strong  in  tension.  They gain their holding power by digging deep into the bottom  rather  than  lying  as  a  deadweight. Both the Mk 2 LWT anchor and the wedge block LWT anchor have high holding power for their weights. The 30° fluke angle on the wedge block LWT anchor is most effective in sand bottoms; and the 50° fluke angle, in  mud  bottoms.  For  example,  both  10,000-pound  LWT anchors are designed to have a holding power in a sand bottom slightly higher than the 22,500-pound standard Navy stockless anchor. They are used as bower and stern anchors and may also be used as stream or kedge anchors. Anchors less then 150 pounds are normally used as small boat anchors. The main characteristic of the LWT anchor is the placement of large flukes at such an angle that they drive deep into the bottom to ensure good holding power. The crown is designed to lift the rear of the flukes and force their points downward into the bottom. Good stability is also obtained by placing the flukes close to the shank. These  anchors  are  extremely  useful  in  any  situation where lightweight but good holding power is essential. They have even been cast up to 3,000 pounds for use as stern anchors on LSTs. For Navy use, LWT anchors are made in approximate weights from 8 pounds to 13,000 pounds, for the Mk 2 LWT 6,000 pounds and 30,000 pounds for the wedge block LWT. The commercial Danforth anchor, shown in view E of figure 4-1, is used on some Navy craft and small boats. TWO-FLUKE BALANCED-FLUKE ANCHORS The two-fluke balanced-fluke anchor (view G of figure 4-1) is used for anchoring some surface ships and the newer submarines and is normally housed in the bottom of the ship. This anchor is used on certain combatant-type surface ships in place of a bower anchor, which could interfere with the ship's sonar dome. STOCK  ANCHORS Old-fashioned,  or  stock,  anchors  (view  H  of figure 4-1) have been abandoned by large merchant and Navy ships because they are extremely cumbersome and difficult to stow. Because of their superior holding power, stock anchors are still used on some boats, and yachtsmen use them for small craft. MUSHROOM ANCHORS Mushroom anchors are shaped like a mushroom with a long narrow stem serving as the shank. Because of their excellent holding ability, they are used for permanent moorings and as anchors for channel buoys and  other  navigational  aids.  The  mushroom  anchor (view I of figure 4-1) is used to anchor buoys and torpedo testing barges. The rounded part, or crown, strikes the bottom first, and the upper surface of the mushroom is cupped to provide a biting surface. As the anchor shifts back and forth under strain, it digs itself deeper into the bottom, thereby increasing its holding power. Consequently, it takes a firm hold and remains fixed under the most adverse conditions. Because the mushroom anchor has no projecting stock or flukes to foul, the moored object can swing freely around a mushroom  anchor.  However,  since  a  mushroom  anchor will break out if the direction of pull is reversed, it is normally  used  only  in  groups  of  three  or  more, surrounding the central mooring point. Certain older class  submarines  use  this  type  of  anchor. CHAIN  AND  APPENDAGES Present day Navy anchor chain of the flash butt welded  type  is  the  Navy  standard  for  new  ship constructions  and  replaces  die-lock  chain  as  required 4-3

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