Friday, December 14, 2012

Selecting an Anchor for Your Ship Model

Selecting an Anchor for Your Ship Model Anchors The first anchors were probably made of stone. The disk-shaped stones had at least one hole in the middle, to attach the line, and the stone anchors probably could serve as ballast as well. Stone anchors have been used in parts of the world until historical times. In Roman times, in the Mediterranean, ship anchors were made of either lead and wood, or entirely of iron. After Antiquity, European anchors are mostly made of iron, often with a wooden stock. From the 19th century, the stock was made of iron instead of wood. Also, the anchor rope was replaced by the anchor chain Anchors should be selected by the era in which the ship was in service. In an earlier article, we spoke of needing to decide early on in the ship model build how you will be displaying the model. All fittings including the anchor should be displayed in conjunction with how the ship is cast i.e. in port, running at sea, in harbor or in battle. The anchor should be attached to your ship model by running a piece of chain through the shackle. A length of rope is then attached to the chain and attached to the windlass. There are many ways of running the rope through the ship to the windlass. There should also be a line attached to the crown that’s used as a trip line to free the anchor form the bottom of the sea should it become entangled. Cast Your Anchor has a large selection of different types of anchors used through the ages. Depending on the size of the ship 3 to 10 anchors and their cables made up the vessels ground tackle. Warship carried an anchor at each side of the bow, and two or more lashed to the channels. Parts of an Anchor Before we examine various types of anchors, we should become familiar with the parts of an anchor. Any anchor consists of the ring (shackle), shank, stock, arms, crown and the fluke or palm. The Ring, or Shackle is attached to the upper part of the shank, to which the cable or chain is attached. The Shank is the perpendicular or middle piece of an anchor. The Stock is made of wood or iron ; if iron, it reeves through the lower hole in the upper end of the shank ; if wood, it is built round the shank, at the same place, and hooped and bolted together ; it stands at right angles to the arms, and being much longer, cants the anchor with one fluke down, which causes it to hook to the ground. Arms are the two triangular pieces at the lower end of the shank, forming hooks, one of which is always hooked or buried in the ground when the anchor is let go, so as to hold the ship in a stationary position. The extreme end of the arm is referred to the bill or pee. The Crown is the lower end of the shank, where the arms or flukes are joined. The Fluke or Palm is the broad triangular piece within the extreme end or bill of the arms. It is so constructed as to have a greater hold of the ground. Bower and Sheet Anchor The bower anchor was used primarily for anchoring the ship. The largest one, called the "best bower" was carried from the cathead at the starboard bow. A sheet anchor is a spare bower. Spanish Anchor The Spanish Anchor is typical of seventeenth to eighteenth century anchors. The general form associated with this time period has a classic arrow shape with a long shank, angular arms, and a wooden stock. Early 18th Century Anchor This kind of anchor was used on British ships, characterized by a straight shank with two arched arms ending in leaf-shaped flukes.At one end of the shank there are two arms, carrying the flukes, while the stock is mounted to the other end, at ninety degrees to the arms. When the anchor lands on the bottom, it will generally fall over with the arms parallel to the seabed. As a strain comes onto the rode, the stock will dig into the bottom, canting the anchor until one of the flukes catches and digs into the bottom. Kedge Anchor In yachts, a kedge anchor is an anchor carried in addition to the main, or bower anchors, and usually stowed aft. Every yacht should carry at least two anchors – the main or bower anchor and a second lighter kedge anchor. It is used occasionally when it is necessary to limit the turning circle as the yacht swings when it is anchored, such as in a very narrow river or a deep pool in an otherwise shallow area. For ships, a kedge may be dropped while a ship is underway, or carried out in a suitable direction by a tender or ship's boat to enable the ship to be winched off if aground or swung into a particular heading, or even to be held steady against a tidal or other stream. Historically, it was of particular relevance to sailing warships which used them to outmaneuver opponents when the wind had dropped but might be used by any vessel in confined, shoal water to place it in a more desirable position, provided she had enough manpower. Grapnel Anchor Used to drag the bottom for lost objects, and to anchor small boats. A traditional design, the grapnel is merely a shank with four or more tines. It has a benefit in that, no matter how it reaches the bottom, one or more tines will be aimed to set. In coral it is often able to set quickly by hooking into the structure, but may be more difficult to retrieve. Grapnels rarely have enough fluke area to develop much hold in sand, clay, or mud. It is not unknown for the anchor to foul on its own rode, or to foul the tines with refuse from the bottom, preventing it from digging in. On the other hand, it is quite possible for this anchor to find such a good hook that, without a trip line from the crown, it is impossible to retrieve. Danforth Anchor A lightweight burying type of anchor with a high holding power to weight ratio. Works best in sandy, muddy or clay bottoms. It uses a stock at the crown to which two large flat triangular flukes are attached. The stock is hinged so the flukes can orient toward the bottom (and on some designs may be adjusted for an optimal angle depending on the bottom type). Tripping palms at the crown act to tip the flukes into the seabed. The design is a burying variety, and once well set can develop high resistance. Its light weight and compact flat design make it easy to retrieve and relatively easy to store. The fluke anchor has difficulty penetrating kelp- and weed-covered bottoms, as well as rocky and particularly hard sand or clay bottoms. If there is much current, or the vessel is moving while dropping the anchor, it may "kite" or "skate" over the bottom due to the large fluke area acting as a sail or wing. Once set, the anchor tends to break out and reset when the direction of force changes dramatically, such as with the changing tide, and on some occasions it might not reset but instead drag. Navy Anchor A heavy ship’s anchor with large flukes and no stock so that the shank can be drawn through the hawshole. The enormous weight of these anchors make them inappropriate for a small vessel.