Anchoring Aluminum Boats: The Ultimate Guide To Safe Mooring

Anchoring an aluminium boat requires careful consideration of the type of anchor, weight, and material, as well as the length of the line, number of anchors, and the presence or absence of a chain. The type of water body and its bottom composition, such as sand, mud, rocks, or weeds, play a crucial role in determining the appropriate anchor. For instance, a mushroom anchor is suitable for calm waters and temporary fishing stops, while a folding grapnel is preferred for rocky or weedy bottoms. Additionally, the size and weight of the boat must be taken into account when selecting an anchor.

Anchor weight and type

The weight and type of anchor you need for your aluminium boat will depend on several factors, including the size and weight of your boat, the weather and currents you expect to encounter, and the conditions of the water bed.

As a general rule, the heavier the boat, the larger and heavier the anchor should be. However, anchor weight is not the only factor to consider. The holding power of an anchor—the amount of pull force it can withstand—is also important, and this is influenced by environmental factors like wind speed. For example, a holding power of 90 pounds is sufficient for safely anchoring a 20-foot boat in winds up to 20 miles per hour.

The type of water bed you are anchoring on will also play a role in determining the type and weight of anchor you need. Harder surfaces like rocky bottoms or coral require anchors with more grip, while softer bottoms like sand or mud are more suitable for anchors that can penetrate the surface.

Some common types of anchors include:

• Fluke anchors (also known as Danforth anchors) are lightweight and have excellent holding power in soft bottoms like sand or mud. They are suitable for boats up to 30 feet in length and are not recommended for rocky bottoms or strong currents.
• Plow anchors (or delta anchors) are simple and effective, providing reliable mooring in most water conditions and beds. They dig into the surface and provide high holding power, making them a good choice for strong currents and winds. However, they can get stuck in large rocks or debris, so they are best suited for softer bottoms. Plow anchors are suitable for boats up to 70 feet in length.
• Claw anchors (or Bruce anchors) are similar to plow anchors but with smaller pins, making them better suited for gravel and rocks. They set quickly and dig into soft bottoms, providing good holding power. Claw anchors are ideal for boats up to 40 feet in length.
• Digger anchors have high holding power in gravel and rocky bottoms, even in strong currents and high winds. They use a rod that partially rotates, allowing the anchor's claws to dig further into the bottom. Digger anchors are suitable for boats up to 40 feet in length and should be avoided in bottoms with large debris.
• Navy anchors are classic, heavy anchors that provide high holding power in all waters and conditions, including rocky bottoms and debris fields. However, their large size and weight make them difficult to store and not ideal for smaller vessels.
• Mushroom anchors are designed for small vessels in relatively calm waters with soft bottoms. They rely on suction and sinking into the sand, dirt, or mud to provide holding power. Mushroom anchors are typically found on kayaks, dinghies, or light electric motor-powered boats up to 12 feet in length.
• River anchors are similar to mushroom anchors but are suitable for small vessels in lakes and rivers with rocky bottoms or beds filled with debris. They work well in soft bottoms but have less holding power than mushroom anchors. River anchors are also intended for boats up to 12 feet in length.

Anchor rope length

The length of anchor rope you need depends on the depth and current conditions of the water you are anchoring in. The Coast Guard recommends a 7:1 scope, meaning that if you are anchoring in 10’ of water, you would use 70’ of rope. However, this is for extreme conditions and most people use a 3:1 or 4:1 scope in moving rivers. In a lake with little current, you could use a 1:1 or 1:1.5 scope. For example, if you are in 50’ of water, you could drop straight down with 50’ of rope.

It is recommended to have 8 feet of rope for every 1 foot of water you will be anchoring in. You should also have 1 foot of chain for every 1 foot of boat. So, a 30' boat would want 30' of chain. However, if there are weight or locker room constraints, you should have at least 10-15' of anchor chain.

For a 14' aluminum boat, you could use 100ft of anchor rope. For a 19' boat, 3/8" rope is recommended.

Stern anchors

When using a stern anchor, it is common to use only anchor rope without a chain. The anchor is typically dropped straight down off the corner of the boat. The weight of the anchor depends on the size and type of boat, with smaller boats requiring lighter anchors. For instance, a 12-foot boat may use an 8-pound anchor, while a 15-pound anchor may be more suitable for a 20-foot boat.

It is also important to consider the length of the anchor rope. A longer rope provides more flexibility in anchoring, allowing you to anchor in deeper waters or adjust the distance from the shore. However, a longer rope also requires more storage space and can be more challenging to handle.

In addition to traditional anchors, some boaters have found creative solutions for anchoring their boats. For instance, a strong mesh bag filled with rocks can provide a low-cost and effective anchor. Another option is to use a cinder block, which is cheaper and easier to replace if lost.

Anchor trolleys

An anchor trolley is a device that allows you to easily and quietly set your anchor at the bow, amidships, or stern of your boat. It is particularly useful for small boats in calm waters, such as ponds and small lakes with light winds.

When using an anchor trolley, it is important to use your prudent judgment about when to deploy any anchoring system. While anchor trolleys can be helpful in certain situations, they should not be used in big wave conditions. For example, when anchored under a bridge with a gentle current, positioning your boat bow-first makes sense. On the other hand, when sitting just outside a lily pad flat with the wind at your back, it might be best to position the anchor at the stern to allow for forward casting. Amidships might be the best option when floating alongside a beaver lodge and needing to work the areas quietly.

There are various anchor trolley kits available on the market, such as the LeverLoc Anchor Trolley, which includes a line clamp that locks your trolley line in place and a PadHook to keep the lines in line. These kits typically come with all the necessary hardware for installation and range in price from $34 to $45.

When using an anchor trolley, it is important to consider the type of bottom you are anchoring on, as well as the depth and current. For example, a mushroom anchor may work well in calm conditions or for temporary fishing stops, but it may not have enough holding power in rocky or weedy bottoms. In such conditions, a folding grapnel anchor or a Danforth anchor may be more suitable. Additionally, it is recommended to use a chain with your anchor, especially if you are anchoring in rocky bottoms where the anchor may get wedged.

Anchor storage

When it comes to storing your anchor, there are a few options to consider, depending on the size of your boat and anchor.

For smaller boats with lighter anchors, an anchor bag is a good option. These bags hold the anchor and the rode (the rope or chain attached to the anchor). Another option for small boats is a rail-mounted holder designed for the type of anchor you have, such as a Danforth-style anchor. This keeps the anchor conveniently located and readily accessible.

If you have a bigger boat, an anchor roller attached to the bow is a good choice. This setup is especially useful if you need to quickly deploy the anchor.

For those with limited storage space on board, a 5-gallon bucket can be a solution. The bucket can be bolted to the deck and used to store the anchor, rode, and chain. Alternatively, a milk crate can be used to store the anchor chain and rode, along with a spare anchor.

When storing your anchor, it is important to consider the weight and size of the anchor, the available space on your boat, and how quickly you need to access and deploy the anchor.

Frequently asked questions