Choosing an anchor is not just about buying an accessory, it's about your safety on the water. Many inflatable boat owners make the mistake of relying on intuition or the advice of sellers, ignoring the physical laws of hydrodynamics. Right weight anchor ensures that the boat does not break off when the wind or current is amplified, which is especially critical at night or in an unfamiliar body of water.
There is a common misconception that for a light inflatable boat, it is enough to throw any heavy iron into the water. sailability The inflated PVC cylinder is much higher than the rigid hull, which puts an excessive load on the anchor cable even in moderate winds, which is why the calculation of the mass should be accurate, not approximate.
In this article, we will discuss the proven calculation methods, present current tables and discuss the nuances of using different types of anchors on inflatable vessels. You will learn why it is sometimes more profitable to take an anchor slightly heavier than the calculated one, and how the shape of the legs affects the effectiveness of retention in different soils.
Formula for calculating the mass of anchors for inflatable boats
The basis for the selection of anchoring devices is the length of the vessel along the waterline. There is a classic empirical formula that allows you to calculate the minimum required mass of the anchor in kilograms. M = k * Lwhere M is the mass of the anchor, L is the length of the boat, and k is the coefficient, depending on the type of design.
For lightweight inflatable boats with low sailing and flat bottom, the coefficient is usually taken to be 1.0. However, if you plan to use the boat in windy weather or the boat design has a high superstructure, the coefficient should be increased to 1.25 or even 1.5. Anchor mass It must compensate not only for the inertia of the boat, but also for wind pressure.
⚠️ Warning: Never use the full length of a boat with inflated cylinders around the perimeter to calculate, only the length of the usable space (cockpit) or the distance from the transom to the nose jar, as this part is under the influence of water.
Consider an example: for a boat with a length of 3.2 meters, the minimum weight of the anchor will be 3.2 kg. Round up to a standard value of 4 kg. If the boat is used on a river with a strong current, it is better to add 20-30% to the weight for reliability.
Table of correspondence of the length of the boat and the weight of the anchor
To avoid making complex calculations every time, it is convenient to use ready-made reference data. Below is a table compiled from many years of experience in operating small craft in different conditions. recommended minimums for calm water.
It is important to understand that the data in the table are relevant for anchors of a classical construction with paws (for example, Denforth or Hall). gravity anchors (just a load without paws) the mass must be increased by 1.5-2 times, since they are held only by their own weight, and not by burying in the ground.
| Boat length (m) | Min. anchor weight (kg) | Optimal weight (kg) | Diameter of cable (mm) |
|---|---|---|---|
| 2.4 – 2.9 | 2.0 | 3.0 | 4 – 5 |
| 3.0 – 3.5 | 3.5 | 4.5 | 5 – 6 |
| 3.6 – 4.2 | 4.5 | 6.0 | 6 – 8 |
| 4.3 – 5.0 | 6.0 | 8.0 | 8 – 10 |
When choosing, consider the diameter of the cable or rope. A too thin squirt can break when jerking, and a too thick one can take up a lot of space and get confused. The optimal balance between strength and ease of storage is shown in the last column of the table.
If you often fish on the current, use the anchor 1-2 kg heavier than the table for calm water.
Effects of soil type and operating conditions
The mass of the anchor is not the only factor that affects the reliability of the parking lot. bottom-type On slurry or sandy ground, an anchor with paws is buried and holds a boat 10 to 20 times its own weight, and on a rocky or clay bottom, this effect is virtually absent.
If you're planning to fish on clay-bottom rivers, a classic cat anchor can simply slide across the surface, regardless of its weight, and you either need to increase the mass or use special anchors with spikes or flat soles that can catch on to irregularities.
⚠️ Warning: In areas that are heavily overgrown with grass or boulders, the anchor can get stuck dead, in which case even a light anchor will be a problem, so always carry a buoy or extra supply of cable.
And you also have to consider depth. At greater depths, the rope length increases, and the angle of tension becomes more gentle, which reduces the effectiveness of the anchor. should be heavier than the anchor Or longer cable to create the right angle of attack.
Design choice: Cat, Denforth or Mushroom?
There are many designs on the market, but three types are the most popular for PVC boats. Cat anchor It's a versatile version with folding legs, compact, easy to fit in a funduk, but has a low holding power on hard ground, and its advantage is the ability to cling to rocks or driftwood.
Anchors type denforth They have great holding power on sand and silt, they burrow quickly into the ground, but on a rocky bottom they can just slide across the surface without getting caught, and they take up more storage space because of their geometry.
- 🦀 Cat: Ideal for transportation in a bag, good on stones, but heavier than analogues of the same holding power.
- ⚓ Denforth: The best choice for sand and silt is compact in disassembled form, but is afraid of algae and stones.
- 🍄 Mushroom: Suitable only for a sluggish bottom, very heavy for its size, useless on the sand.
For most owners of PVC boats up to 4 meters long, the best choice would be a folding cat weighing 4-5 kg or a compact Denforth. If you fish mainly in reservoirs with a muddy bottom, Denforth will be more efficient. For rivers with a rocky bottom, you better take a cat.
Why is the mushroom anchor almost not used on PVC?
The mushroom anchor holds only by its own weight and suction to the silt. On sand or pebbles, its holding force is zero, and the weight to work effectively must be huge (10+ kg), which is inconvenient for a light boat.
Anchor cable and proper organization of parking
Even the heaviest anchor won't hold a boat if it's not organized properly. anchor-lineFor inflatable boats, it is strongly advised not to use chains as the main part of the rope. The chain is too heavy, can damage cylinders with careless choice and takes up a lot of space.
The best solution is to use a synthetic cable made of polypropylene or nylon. These materials are not sinking (polypropylene) or have minimal water absorption, are tensile and easy to work. The cable should be at least 3-4 depths in the parking lot to ensure a gentle angle of tension.
It's important to get the rope right on the boat. You can't just tie it by the handle on the balloon, because if you push hard, the handle can come off, and you lose anchor with the boat. Use it. squirrel, glued into a transom, or special liner devices distributed on the sides.
☑️ Checking the anchor system
Frequent errors in selection and operation
One common mistake is to buy an anchor "on growth": owners of small boats often take anchors weighing 8-10 kg "just in case", which leads to the boat becoming unstable on the wave, and the sampling of the anchor by hand turns into hard physical work, dangerous for the inflatable board.
Another mistake is ignoring the condition of the cable, and the synthetics are exposed to ultraviolet light and abrasion, and if the cable has any rags or has changed color, the strength of the cable drops. rope-stage before every season.
And many people forget about the case, the anchor in the boat should be in a separate bag or box, and the sharp edges of the paws can imperceptibly damage PVC tissue during pitching or active fishing, leading to balloon injury and potential flooding.
⚠️ Warning: Never wind an anchor cable on your arm or leg when sampling an anchor! with a sharp snatch of a boat or anchor getting stuck, this can lead to serious limb injuries or even pulling a person overboard.
The right approach to choosing an anchor is to balance weight, shape and operating conditions, and you shouldn't skimp on this piece of equipment, because it is often the last hope in an emergency.
Golden rule: The weight of the anchor in kg should roughly correspond to the length of the boat in meters, but for PVC it is better to add 20-30% of the margin due to the high sailing.
Questions and Answers (FAQ)
Can a bunch of bricks or stones be used instead of an anchor?
You can use it, but you don't recommend it. Bricks are smooth and don't hold well, they can crumble quickly, and the sharp edges of the stones can damage the boat's cylinder when you lift them up, and you'd better buy a specialized anchor that's designed to be buried.
Which anchor is best for a 3.2 meter long boat?
For a boat with a length of 3.2 meters, the best choice will be an anchor weighing 3.5-4.5 kg. If the bottom is sandy or slurry, a folding Denforth is perfect. For universal use (stones, grass, sand), it is better to take a classic cat weighing 4 kg.
Do I need to lubricate the anchor before storage?
Yes, the metal parts of the anchor (especially if it is not stainless steel) need to be cleaned of sand and salt, dried and lubricated with conservation lubricant or oil. This will prevent corrosion, which can weaken the structure in one season.
What if the anchor is stuck dead?
Don't pull the boat abruptly, it's dangerous. Try moving the boat in different directions, changing the angle of thrust. If you have a thrust-off mechanism (the ring at the top of the anchor), pull the rope tied to it. In extreme cases, if the anchor is not sorry, you can use the method of "washing" with a jet of water under pressure around the paws.