Home - Anchors, Anchor Chains and Rode - Which is Best for your Boat?

Anchors, Anchor Chains and Rode - Which is Best for your Boat?

Anchor Selection - What Size and Type do I Need for my Boating Style?

Anchors their importance and how they are used and function very often is misunderstood by your average boater. We are going to cover all the key elements to properly equip your vessel so you’re ready to “Drop the Hook” like a pro. The most important thing is to get familiar with what types of anchors work best for your boating conditions. The equipment selected should always be matched not only to your vessel but the type of bottom you intend to anchor you vessel to. Whether its sand, coral, rock, mud or sea grass there is an anchor specifically designed for those conditions. The other crucial factors are the size, type and windage of the boat to be anchored, as this will dictate the size and weight of the anchor as well as considering tides, currents and other boats or obstructions near your vessel that you want to avoid.

Very often here in Florida where I live and in many other areas the prime locations or anchorages can be very crowded, requiring the use of multiple anchors. Sometimes it is necessary to set two anchors off the bow to increase holding power and control swing of the vessel in rough seas or high winds, and other times you might set one off the bow and another off the stern. If you fail to properly evaluate all of these factors and deploy the right anchor type with the correct amount of chain and scope (that is the length of rope and chain) your vessel could swing or even break free from its anchorage. Remember in heavy winds the holding power of your ground tackle (anchor, chain and rode) will be put under immense stress. Typically as the wind speed doubles the force on the anchor increases by four times and it’s never fun trying to secure a boat that has dragged its anchor in rough seas or heavy wind.

Types of Anchors

Let’s review the different types of anchors. One of the most popular anchor styles today is the Lightweight Fortress Marine Anchor similar in design to a Danforth, with several major differences. Fortress anchors are made from aluminum alloy that is as strong as steel, but only half the weight, and is typically the sole anchor on many smaller boats. Light and easy to weigh (lift off the bottom), it stows flat and holds very well in mud or sand. It’s excellent holding power–to–weight ratio means you can use a lighter anchor compared to other types, but it doesn't hold well in grassy or rocky surfaces. The flukes and stock (the wide crossbar at the top) are more prone to foul on rocks or the anchor line.

The best anchors suited for rocky bottoms are plow anchors, the "single point" style represented by Delta and Claw, which have the best holding ability in varying bottom conditions from rocks to sand or even gravel. They generally reset themselves easily if the wind or current changes direction, and hold effectively in grass, mud and sand. They do not have projecting flukes that foul easily, but rely more on sheer weight for holding power. Their shape makes stowing them more awkward (a bow–roller or bow-pulpit is the best solution). Heavier displacement powerboats and cruising sailboats generally set a plow anchor as their primary anchor. Again I can’t stress enough the importance of having multiple anchors of varying styles to ensure you have the right gear for the conditions. Also anchors can become fouled on the bottom and lost, so it’s good to have a back-up!

Anchor Chain - How Much is Enough?

The length of chain will vary depending on the length of you boat and the size and type of anchor to be used. Typically the more chain the better for two reasons. First of all is the fact that often bottom conditions are quite rough and chain provides superior abrasion resistance. The second is that the weight of the chain helps set the anchor on the bottom, and ensures that as your vessel rocks up and down with the waves the anchor has reduced pull on it because the chain lifts off the bottom not the anchor. The actual size and length of chain should be calculated based on the length of your boat. Typically 50 – 100’ of high test chain spliced to 250 - 300’ of nylon 3 strand line is a perfect combination. Again be sure to take into consideration all of the elements of your vessel’s anchor system including not only the size and weight of the anchor but also the anchor retrieval system... be sure you can handle pulling in your ground tackle gear manually if your boat doesn’t have a windlass.

Anchoring Techniques - Offshore vs. Inshore

Anchoring off shore can be a difficult task. It is very beneficial to have plenty of rode so you can achieve the desired scope. Scope is defined as the ratio of water depth (plus freeboard, the height of the boat from the waterline) to anchor line paid out. Many professional captains and anchor manufacturers agree that a scope of 7:1 achieves the anchor's designed holding power, and more scope is better than less -- 7:1 scope is great, but at a crowded anchorage many cruisers will not pay out more than 3:1 or 4:1 as there just isn't that much space for boats to swing. When an anchor is securely set you can consider shortening scope in a crowded anchorage. Once an anchor has been set, it will generally always hold the same amount of tension that was used to set it, even if the scope is reduced. This means that you can pay out long scope, pull hard on the anchor rode using the engine, and then shorten scope to reduce swinging room. However, if your boat swings and the anchor resets itself, it will have to do so at a reduced scope. This is why many sailors will opt for the two anchor approach whether its one off the bow and another at the stern or a double set Bahamian style system off the bow. Whichever way you plan to anchor be sure to use plenty of force by backing down with the engine to ensure a good set of the anchor and stretch the rode.

Anchor Rodes, Shackles, and Retrieval Systems

Anchor rodes should be sized to match the size of your vessel and anchor. If your vessel is equipped with a windlass or anchor winch the size of rode needs to be matched to the windlass. Some windlasses will accommodate rope and chain others only work with chain. The length of you rode depends largely on where you are going to be anchoring, clearly if you plan on cruising offshore to deep water then you will need significantly more chain and rope to effectively anchor your boat. A regular thorough inspection of the entire anchor system should be performed be on the look out for chafing, deterioration of chain to rope spices, and anchor shackles and pins for corrosion. For more information on outfitting you vessel with the right equipment see our detailed anchor selection guide or send us email sales@marinesupplydock.com to contact one of our rigging specialists.