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ANCHORS & ANCHORINGpt 2
Anchors and Ground Tackle Part 1 of Anchors & Anchoring looked at all the various anchor types anchor makers and how to choose the anchor which is best suited for you and your boat or vessel. Anchors and Ground Tackle looks at the rest of the ground tackle the Anchoring Gear, & Anchor Equipment that attaches your boat to the anchor.
Ground tackle refers to all the parts of an anchor package between the boat and includes the anchor. If you use only line the ground tackle may be referred to as simply the anchor line.
All chain Ground Tackle All chain is popular on large boats, heavy displacement boats, large power boats and Mega Yachts. The two benefits of chain are weight and chafe. Weight keeps the chain on the seabed which keeps the angle of the anchors shank close to parallel with the bottom.
The second issue with all chain is lack of stretch. This manifest itself in 2 ways. First in a swell and wind the boat is moving around over the anchor. As the boat gets further away, the ground tackle will load up and pull the boat back to the middle. This loading up will transfer to the boat and the crew will feel the jarring. Crew may even fall down because of this shock loading. Here it is necessary to have an anchor snubber to dampen the load. The second result from lack of stretch with all chain is again anchoring in a swell. Here the load from the vessel is transferred through the chain and the forces transferred to the anchor, possibly braking it free. Again using a snubber with dampen the load. Chain comes in 3 types. To learn about these types of chain follow this link All rode Ground Tackle For smaller boats having an all rope, anchor line, warp or rode is more popular. It is lighter, can be thrown, takes up less space and stretches. The down side is chafe. Unlike chain rope stretches and this results in a smoother ride at anchor. When the boat swings at anchor and loads up the line, the load is dissipated by the stretch in the line. Unlike with Chain the load is not transferred to the anchor, and so the anchor is not effected.
Polypropylene has good stretch floats but has poor shelf life in the sun. Three-strand line can absorb shock and the constant tugging associated with anchoring much better than braided line. Nylon Three-Strand line is the leading choice for use as an anchoring line. Lines generally come in a "soft" or "medium" lie. Soft lines are generally softer and loosely woven, than medium or hard lines for anchoring, as they are more prone to unraveling and chafing. Medium and hard lines are best to handle chafe. Lines that have been treated with a wax-like coating are available, and can help the line resist water/salt absorption.
Chain Rode combinations Since all chain or all rode have their pros and cons a combination chain and rode is most popular. Here the chains weight and chafe characteristics prove their worth on the seabed. The rode proves its woth with the stretch, so dampening any shock loads from the boat swinging around. Also the rode takes up less space. So how much chain should we use. In the next section we look at how much anchor rode ground tackle you will need. This is calculated on scope. Scope is the ratio of water depth to line put out. This ratio is somewhere between 3:1 and in extreme cases 10:1. How much chain to rope
some rules of thumb say one ft of chain per foot of boat length. Another says one lb of chain for every pound of anchor. Chain to Rode length calculation Earl Hinz, a former aeronautical engineer and inveterate Pacific Ocean sailor, in his work The Complete Book of Anchoring and Mooring, says the chain lead should weigh at least as much as the anchor whose weight it is supplementing.
From his
experience, he has determined that the length of the chain lead has nothing
to do with the depth of the water or the length of the boat. He suggests
using the following formula to help you determine the minimum
Anchor materials factor = 1 for steel and 1.6 for aluminum For example: If you have a 7-lb. Fortress aluminum anchor with a 1/2 inch twisted three-strand nylon rode, you would need to use at least 11.2 lbs of 5/16 inch proof coil chain, which weighs 1.15 lbs per foot. Therefore, you will need at least 9 ft 8 inches of boat anchor chain. Weighted Anchor Rode If you need an anchor line but do not want to add chain you can opt for a weighted anchor line. The idea of a weighted line is that the whole line sinks and holds a strong catenary curve. This would be similar to how a chain falls. The curve helps damping and provides better anchor holding. FSE Robline is one manufacturerThe benefit of a weighted line is you can have the weight closer to that of chain, but without the harsh handling, You can lead the line over a gunwale or side deck without damaging the surface. Also good for RIBs and Inflatables. The line is also much quieter than chain, plus it does not leave rust stains.
Anchor Chain types
Proof coil chain is made of low-carbon steel. It
usually will have "G3" cast into each link. Its name comes from subjecting
the chain to tensile loads (its proof load) until it breaks.. Anchor
chains working load rating is usually 50 percent of the proof load.
Proof coil is usually the least expensive chain, since it has fewer links
per foot. Proof coil will not work with a windlass. COATINGS All these chains are galvanized. Some anchor chain can be purchased with a thin polymer coating. Vinyl coatings are also used. which makes the chain thicker, but gives more protection. Stainless-steel anchor chain is also available. This is 316 stainless and is stronger than the steel, galvanized counterparts, but not as strong as high-carbon HT galvanized chain. It is also considerably more expensive than any of the galvanized chains. It does, however, prevent rust stains.
This splice by animated knots lets you see the splice step by step. You can use an eye splice and shackle but this
will not work with a chain rode Windlass.
What chain diameter do I need and what line size do I need. These diagrams from the ABYC will help you decide.
This Chart from part 1, gives you an anchor horizontal loads at various wind speeds. For our 30 ft boat the horizontal load is 700 lbs for a Working Anchor which is rated at 30 knots. Below you will se that for this boat 7/16 inch line is recommended and 5/16 inch chain.
A swivel allows the anchor to settle on the seabed and the anchor chain or line to align to pull horizontally. Many swivels operate in one plane only. This swivel can articulate as well as swivel.
Retrieving an boats anchor is best done by motoring up to the anchor. Do not use a
windlass to haul yourself to the anchor. Once at the Anchor pull the ground
tackle rode tight, and then move weight aft and let the boat lift the anchor.
Anchor can be hard to get to dig in, but when they do they can be hard to get out. Retrieval systems help breaking the anchor free of the bottom. The AnchorLift is one example of an anchor retrieval system.
When lying at anchor boats tend to roll. Roll stabilizers or Rocker Stoppers combat this. Davis Rocker Stoppers help dampen the rocking motion of boats at anchor. Simply tie Rocker Stoppers approximately 44 cm (18") apart, making a string of them, with a 5-10 pound weight attached at the bottom of the string. If a rocker stopper is not enough try a stabilizing fin which is a mechanical fin controlled by software. Use on larger boats, the software changes the angle of the fin to appose the roll motion. Some stabilizers for anchored boats are called Zero speed stabilizers.
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If this angle gets too
great then the anchor can break free. With the chain on the seabed, it is
subject to chafe, and chain can withstand chafe much more than rode, rope
or warp.
Twisted three-strand
nylon rode, has good stretch properties, it also sinks. For the rode a
nylon line is very strong and with the 3 strand construction has lots of
stretch
Chain Snubber 
