Choosing the right anchor for an inflatable boat is not just a matter of convenience, it's a critical component of safety on the water. PVC boats They make a common mistake of relying on intuition or advice from friends, which often leads to unpleasant situations on fishing or rest. Insufficient weight of the anchor will not hold the boat when the wind is increased, and excessive can cause transom damage or even overturning when a sharp jerk.
In this article, we will discuss proven calculation methods that take into account not only the length of the hull, but also the wind load, the type of bottom and the specifications of your boat. Encyclopedia of Water Engines It recommends approaching this question with mathematical precision to avoid drifting into the fairway or losing tackle. Understanding the physics of the process will help you choose the perfect anchor, whether it is a classic "cat" or a modern folding option.
Ignoring the calculations can cost you not only spoiled fishing, but also expensive equipment. Anchor system It has to be balanced, the anchor, the rope and the anchor point work together, and if one piece is wrong, the whole system loses efficiency, and let's look at what the weight of the load depends on and how to calculate it without any complicated engineering work.
Factors affecting the choice of anchor device
When choosing an anchor for flyboat You have to take into account a combination of factors, each of which contributes to the overall picture, first of all, the sailing area of your vessel, the high sides and the installed awning significantly increase the resistance to the wind, requiring a heavier or more tenacious anchor than low kayaks.
The second critical parameter is the type of bottom in the pond where you plan to fish, and the shape of the paws that is important for the slurry or sandy bottom is the shape of the paws that allows for instillation, whereas on rocky soil you need an anchor that can catch on to irregularities. Cat anchor It is versatile, but on soft silt it can simply slide across the surface if its weight is picked up incorrectly.
⚠️ Warning: Never tie the anchor tile to inflatable tubes or handles. The anchoring point should be strictly on the transom or on a special loose bolt in the bow so that the boat does not overturn when jerking.
Also (cannot be ignored) the strength of the current and the height of the wave. On a river with fast flow, the weight of the anchor should be increased, because the hydrodynamic resistance of the water acts on the body more strongly than the air currents. anchorage.
- 🌬️ Wind load: Consider the presence of the awning and the height of the superstructures.
- 🌊 Type of reservoir: standing water of the lake or the rapid flow of the river.
- 🪨 The nature of the bottom: sand, silt, stone or shell.
- 🛶 Boat dimensions: length, width and displacement of the boat.
Classic formula for calculating the mass of the anchor
There's a well-established empirical formula that has been used by water-engineers for decades, based on the length of the hull of a boat and yielding a basic weight, and the following relationship is used to calculate: the mass of the anchor (in kg) is equal to the length of the boat (in meters) multiplied by a factor of 1.5, or is taken 10% of the length in centimeters.
However, for PVC boats With their relatively light body and high buoyancy, a gentler but more reliable coefficient is often used. M = L × 1.5, where M is the mass of the anchor and L is the length of the boat. For example, for a boat 3.6 meters long, the minimum weight of the anchor is about 5.4 kg. But this is true for open spaces.
If you use a boat in protected waters where the wind load is minimal, you can use a factor of 1.0. In this case, for the same three-meter boat, an anchor weighing 3 kg is enough. This formula gives the minimum permissible weight for calm weather.In windy weather, this may not be enough.
For PVC boats, it is optimal to have two anchors: light (2-3 kg) for quiet weather and fishing in the snag, and heavy (5-7 kg) for open water and windy days.
And don't forget the anchor material, steel structures are heavier than aluminum ones, if you're going to choose a folding anchor from a single anchor. And the weight of stainless steel is going to be the same as the weight of the calculations, and aluminum models, with the same weight, have large paw sizes, which can be an advantage on soft ground.
Table of correspondence of the length of the boat and the weight of the anchor
To make this easier, we've developed a composite table that can help you navigate quickly when you buy equipment, and that's relevant for standard inland water conditions, and remember that the tabular values are averages.
| Boat length (m) | Min. anchor weight (kg) | Optimal weight (kg) | Type of soil |
|---|---|---|---|
| 2.0 – 2.5 | 2.0 | 3.0 | Sand, silt |
| 2.5 – 3.2 | 3.0 | 4.5 | Sand, clay |
| 3.2 – 3.8 | 4.0 | 6.0 | Mixed |
| 3.8 – 4.5 | 5.0 | 8.0 | Rock, shell. |
| 4.5. and more | 7.0 | 10.0+ | Anyone. |
Using this table avoids gross errors when completing the boat, however, if you plan to go to large reservoirs where the wave can reach a significant height, it is recommended to take the value from the column "Optimal weight" and add 10-15% to it. Safety margin In an anchor system, it is never superfluous.
Effects of wind and current on retention capacity
Wind and current create a dynamic load on the boat that can be many times the static weight of the boat. When the wind is strong, the boat starts to prowl, creating a jerk load on the anchor rope. retention The anchor is being tested for strength.
There is a rule: for every 10 m / s of wind, the load on the anchor should be increased by about 1.5-2 times compared to the calm. If you are fishing on the current, the water flows around the hull, creating a constant tension. In such conditions, the weight of the anchor should be increased, or you need to change the tactics of setting using two anchors.
⚠️ Warning: A boat's sharp jerks in the wind can snatch anchors from the ground even of sufficient weight. Use an anchor cable with a shock absorber or a section of the chain at anchor to extinguish the jerks.
The ratio of the length of the cable to the depth (claric) should be at least 3:1, and in stormy weather - 5:1 or 7:1. This allows you to pull the anchor horizontally, pressing the legs to the bottom, rather than pulling them up.
- 📉 Horizontal traction: The long cable presses the anchor to the bottom.
- ⚓ Chain insert: 1-2 meters of the chain at the anchor improve the angle of attack of the paws.
- 🌪️ Sailing: The awning increases the load on the anchor by 2-3 times.
Choosing the type of anchor for different conditions
Not only does weight matter, but design matters. PVC boats are the most popular anchor cats because of their folding design and versatility. They work well on rocky bottoms, in the snag, and in overgrown areas where other types of anchors can get stuck dead.
Sandy and muddy bottoms are great for Denforth anchors, or their folding counterparts with wide paws, and they quickly bury themselves in the ground, providing high retention power at relatively low weight, but on a rocky bottom, such an anchor can simply slide across the surface without getting caught.
Why is the cat anchor so popular?
The cat anchor (Grapnel) has 4 folding legs. This makes it compact to store in a boat bag. It's versatile: if one paw gets stuck between the stones, others can catch. The main drawback is that it's difficult to pull out if it sits dead in rocks or snags, so it's often used with a buirep (break-away line).
There are also parameter anchors and iron anchors, but inflatable boats are less convenient because of the complexity of transportation and storage. When choosing, pay attention to the presence of sharp edges that can damage cylinders if handled carelessly. Security The number one priority for balloons.
Rules for safe anchoring
Knowing how to calculate weight is useless without knowing how to properly anchor a boat, it is strictly forbidden to anchor from the stern of an inflatable boat when parked in the current or wind, the boat will turn on board to the wave, which can lead to a wave. tipping And water gets in.
Proper staging is always done from the nose. If your boat does not have a bow bolt, use an anchor loop or tie the phala to the ring of the inflatable balloon (only if it is designed and protected from rubbing).
☑️ Safe anchorage
When unarmoring, never pull the rope with your hands if the boat is in the wind - this can lead to injury. Swim to the anchor, select a slack and pull the boat forward to pull the anchor from the ground due to the weight of the boat and the thrust of the engine. If the anchor is set, use the buffet method if it has been installed.
What if the anchor is stuck?
If the anchor is stuck, don't pull the boat back abruptly, which is dangerous. Try to pick the cable as close as possible to the anchor, round the stuck object (if possible) and pull in the opposite direction. If you have a buyrep (a thin line tied to the anchor's head), pull it - this will overturn the anchor and free the paws.
Can I use the cargo instead of the anchor?
Using a heavy load (stone, sandbag) without paws is possible only on very soft silt or as an additional load. The holding power of such an anchor is only equal to its weight in water, while a pawed anchor holds 10-20 times its own weight due to the soil.
Which cable is better: nylon or chain?
For PVC boats, the optimal synthetic cable (nylon, polypropylene) with a diameter of 6-8 mm. It is durable, does not rot and feels pleasant. The chain is used only in a short piece (1-2 meters) at the anchor itself to press it to the bottom. The fully chained tooling is too heavy for an inflatable boat and can damage the cylinders.
So to sum up, a good weight calculation of an anchor is a balance between theoretical formulas and real-world conditions. Don't skimp on this piece of equipment, because it's what makes you safe and secure the boat. Always have a margin of weight and length of the cable, check the condition of the anchor rope before each season, and keep in mind the rules of safety on the water.
The weight of the anchor should be 10-15% of the length of the boat in centimeters, but with strong wind or current, this weight should be increased, compensating for the load with the length of the cable.