Parking safety is not just a convenience, it is a vital necessity for any water-engineer. Incorrectly selected equipment can lead to adrift, collision with other objects or even loss of the boat when the wind is soaring, which is why the question of how to calculate the anchor for the boat is one of the first questions that the owner must decide after buying a boat. Mistakes in the planning stage here are unacceptable, because they will be impossible to fix on the water.
Many beginners mistakenly rely on intuition or advice from friends when choosing a weightlifter by eye. However, the physics of the anchoring process dictates its own rigid rules, ignoring which can be fraught with problems. Wind, current, type of bottom and sailing of your boat should all be considered in the calculations. In this article, we will discuss proven selection techniques that will allow you to sleep well even with a storm warning.
There are several time-tested empirical formulas that are used by seafarers and fishermen around the world, and they allow us to determine the mass required with high precision. anchorage Understanding these principles will help you avoid buying an overly heavy load that will be difficult to lift, or a too light one that will not hold the boat.
Basic formulae for calculating the mass of the anchor
To begin with, we'll turn to the classic formula, which is considered the standard in small shipbuilding, which relates the mass of an anchor to the displacement or length of a vessel. The most common approach is that the mass of an anchor should be about 10% of the displacement of a boat. However, for inflatable and light metal boats, this percentage can vary, since their sailing is often higher and their inertia is less.
More practical for small boat owners is the hull length formula, which is thought to be 1 kilogram of anchor weight for every 1 meter of boat length, which works for moderate wind and calm waters. If you plan to fish in large reservoirs where waves are frequent, the ratio should be increased to 1.2-1.5 kg per meter of length.
⚠️ Attention: When calculating the weight, always consider the full load of the boat. An empty PVC boat has a smaller displacement, but when two anglers land with a load of gear and a motor, its draught and sailing change. Calculate the anchor for maximum load.
There is also a formula that takes into account the area of the midsection (the area of the boat's projection on a plane perpendicular to the direction of the wind). The more the side rises above the water, the stronger the wind pressure. In such cases, the standard weight may not be enough and you will need to weighted or the use of additional cargo.
Effects of bottom type and paw design
Weight calculation is only half of the success. The second half is the anchor's ability to hold onto the ground. Other designs are designed for different types of bottom, and unfortunately, there is no universal solution. If you choose the wrong type, even double weight won't help, the anchor will just drag along the bottom, scratching it, but not entering the ground.
For slurry and sandy soils, which are most common in our latitudes, broad-pawed anchors such as those are ideal. denforth They work like a plow, burrowing into a soft bottom, and in this case, the calculated mass can be minimal, because the holding force is created by a large volume of soil above the paws.
It's a very different situation on a rocky or grassy bottom, where wide legs will slide across the surface or get stuck between rocks, and you need structures with narrow, long legs or pin models that can penetrate the gaps between the rocks. anchor or gruzon They often perform better in difficult conditions, although they require more mass for reliable fixation.
The secret of the double anchor
If you often fish on rivers with strong currents and unknown bottom relief, consider using two lesser-weight anchors instead of one heavy one. One anchor is poisoned from the nose, the other from the stern, which allows you not only to securely fix the boat, but also to turn it with your nose against the current or wind as needed, which is critical for the safety and comfort of fishing.
It's important to note that on a clay bottom that becomes hard as concrete when it dries, the anchor can suck in, and then the excess holding power becomes a problem when it's removed from anchor. anchor-buoy or a special design that allows you to pull the anchor in the opposite direction.
The role of anchor chain and rope
It's often forgotten that the anchor works not alone, but in conjunction with the chain and the rope, and the chain between the anchor and the rope is critical. It has two functions: it weighs the lower part, helping the paw to enter the ground, and more importantly, it acts as a shock absorber. The wind and waves make the chain bend, extinguishing the jerks that could pull the anchor out of the bottom.
The length of the chain should be adjusted according to the depths at which you plan to stand. The optimal is the use of a chain 3-5 meters long. For deep-sea parking, the length of the chain can be increased. The weight of the chain is also taken into account in the total weight of the equipment, but does not completely replace the weight of the anchor itself.
As for the rope (skentel), there is a rule of seven depths: the rope should be 5-7 times the depth in the parking lot. If you stand at a depth of 3 meters, the length of the chosen rope should be at least 15-20 meters, which provides the necessary angle of attack: the rope should pull the anchor horizontally, not up.
Use stainless steel carbines or brass to connect the chain and rope. Cheap silimine carbines can burst under load, and you will be left without anchor. Check the condition of the carbine before each season.
The rope material also matters. The nylon squirtel has good elasticity, which is useful for damping jerks, but it absorbs water. The polypropylene rope does not sink, which is convenient, but it is less durable and wears out faster in the sun. The optimal choice for most boats is to be a very good one. cable with a burst load exceeding the weight of the boat 3-4 times.
Table of anchor selection by boat length
To make things easier, we've developed a composite table that can help you navigate quickly, and these data are relevant for standard conditions: moderate wind (up to 10 m/s), sandy or sluggish bottoms, no strong current.
| Boat length (m) | Min. anchor weight (kg) | Recommended weight (kg) | Bottom type (priority) | Rope diameter (mm) |
|---|---|---|---|---|
| 3.0 | 1.5 - 2.0 | 3.0 | Sand, silt | 6 - 8 |
| 3.0 - 4.0 | 3.0 - 4.0 | 5.0 - 6.0 | Mixed | 8 - 10 |
| 4.0 - 5.0 | 5.0 - 6.0 | 8.0 - 10.0 | Clay, stone | 10 - 12 |
| 5.0 - 6.0 | 8.0 - 10.0 | 12.0 - 15.0 | Anybody | 12 - 14 |
Note that the values in the "Minum Weight" column are only suitable for ideal conditions. If you plan to spend the night on the water or expect wind gain, focus on the "Recommended Weight" column. The safety margin in the anchor system is never superfluous.
For boats longer than 6 meters, tabular data may not be sufficient, as the factor of inertia and sailing of superstructures takes effect. In such cases, it is better to calculate individually, using the formula for depending on the area of the projection of the board.
Specificity of anchors for PVC boats
Inflatable boat owners face a unique problem: where do wet and dirty anchors go? Unlike metal kazaks, PVC boats can't just drop anchor on the floor -- they can damage cylinders. So weight calculation is often limited not only to physics, but also to ergonomics.
An anchor that is too heavy (over 10-12 kg) will be extremely inconvenient to lift by hand while sitting in a low boat, especially if there are hooks at the bottom. cat anchor foldable denforthThey're compact, and they allow you to gain the necessary mass through design, not just by size.
☑️ Checking the anchor system
An important element for an inflatable boat is the presence of a special anchor ditch on the nose, it must be firmly glued; if there is no regular ditch, its installation is mandatory. Attachment of the anchor to the notches or elements of the seats is strictly forbidden - when they are jerked, they can be pulled out, which will damage the balloon and loss of leakage.
Rules for safe anchorage
Even a perfectly designed and matched anchor will not work if the technique of staging is broken. There is a golden rule: the anchor always throws or lowers from the bow of the boat when reversing (or downstream / wind). You can not anchor from the stern - the boat will turn on board to the wave, which is dangerous for stability, especially in windy weather.
So the process is, you go to the parking lot, you put the anchor down, you give a little backing to the anchor to lay down in the wind, and then slowly you get the rope down, allowing the anchor to burrow, and only after you've etched the required length, you can turn off the motor.
⚠️ Warning: Never tie the falin (anchor rope) firmly to the rift of a boat if you are in the area of possible arrival of large boats or on a river with shipping. A sharp jerk from a passing boat can turn over a light boat or tear off the rum, in which case the rope is held in the hand or use an easily torn insert.
When you're unarmored, don't try to pull it out with the power of the motor if it's deep in the ground. Go as close as possible to the parking point (above the anchor), pick a rope slack, pull the boat by the rope, create a vertical force, which will help to tear the anchor off the ground. If you can't, use it. anchor-buoytied to the back of the anchor (top) to pull it by the tail.
The basic principle of safe parking is that the angle of attack of the rope should be as close as possible to the horizontal. The vertical component of the force pulls the anchor upwards, forcing it to come out of the ground, and the horizontal force pushes it deeper.
Frequently Asked Questions (FAQ)
Can a bunch of stones or bricks be used instead of an anchor?
The only thing that you can do is use stones as a last resort, and for a very short time, and the problem with bricks and stones is that they don't have paws that dig into the ground, they have a holding power that comes from friction and weight, and when the wind gusts or the currents change, they break off, and the sharp edges of the stones can damage the rope, and when you lift the brick can break and fall on your feet or damage the bottom of the boat.
Which anchor is better for a river with a strong current: Denforth or Cat?
On a strong current and a dense bottom (clay, pebbles) cat anchor He often performs better because his paws can catch on to irregularities. denforth With the right weight and chain, it burrows deeper and keeps it more secure on sand and silt. Weight is critical for the river: a heavy cat is better than a light Denforth.
Should I remove the anchor after fishing?
After each trip, especially if the boat was used in salt water or muddy, the anchor and chain should be washed with fresh water and dried, the chain should be smeared with waste oil or special lubrication to prevent corrosion, rust significantly reduces the strength of the metal and can lead to a cliff at the most inopportune time.
Why doesn't the anchor hold the boat, even though it's heavy?
There are several reasons: the wrong type of bottom (for example, a smooth rock), too short rope (the anchor reaches upwards, not horizontally), or the bottom is covered with a layer of algae, on which the anchor slides. Also check if the legs are mixed up during the throw. Sometimes it helps to add a small section of chain in front of the anchor to change the angle of attack.