Low-pressure inflatable floors (LBPBs) have revolutionized the small boat world, giving fishermen the comfort of a rigid hull without being overweight. However, many owners make the fatal mistake of treating pumping the floor the same way as a normal balloon or inflatable boards, leading to boat deformation, reduced rideability and even breaking seams at the most inopportune moment.
Proper preparation for getting on the water begins long before you touch the oar or pull for the check of the engine. Critical significance It has a sequence of actions and pressure control at each stage, and in this article we will explore the physics of the process so that your boat will last for decades, maintaining perfect geometry.
Unlike high-pressure inflatable bottoms (HDPDs), which require 0.8-1.0 atms, HPD requires a delicate approach. balloon They pair with stringers to create a single rigid structure, and the violation of the pumping technology turns this tandem into a useless piece of fabric.
Physics of the process: why NDT requires a special approach
The main difference between the DHD technology is the floor design, which consists of two layers of PVC connected by thousands of vertical strands, and when pumped, the top layer is stretched, and the bottom layer is pressed against the ground or water, creating a flat surface. pressure It will be insufficient, the floor will remain soft, and the boat will be worse plane and faster to gain water on the wave.
But pumping is even more dangerous than under-pumping, because stringers are fixed in length, and if you pump the floor more than the size of the stringers allows, there's a tremendous strain on the tear. Air cylinders They will start to squeeze upwards, forming a hump in the middle of the boat, making swimming impossible.
Perfect floor geometry is achieved only when the pressure in the cylinders is balanced by the stiffness of the stringers.
It's important to understand that the volume of air in NDND is huge compared to the sides. So it requires not only more pressure, but also more air to pump it. The use of foot pumps ("frogs") often leads to the fact that the fisherman simply can not physically push the air to the desired values, leaving the floor "cotton".
Toolkit and training required
Before you start, make sure you have proper equipment on hand. For NDNDM, cheap single-cylinder foot pumps are categorically not suitable, as they cannot provide the necessary airflow. two-cylinder Or, much better, a high-quality electric pump with pressure adjustment.
Make sure to use a gauge. The eye meter is your enemy in the case of NDND. By inflating the sides "by eye" to the hardness of the ball, you can get 0.3 atm, whereas the floor requires strictly 0.2-0.25 atm (depending on model and temperature). The difference of 0.05 atm can be critical.
- 🛠️ Pump: electric with a "pumping" mode or two-cylinder foot.
- 📏 Manometer: built-in or separate pump, with a step of 0.05 atm.
- 🧼 Soap solution: Check the tightness of the joints before exiting.
- 🧹 Vetosh: for cleaning the valves from sand and dust.
Step-by-step instruction: the algorithm of correct pumping
The process of pumping a boat with NDND is strictly regulated by manufacturers, and deviation from it is fraught with problems. At first, the sides always inflate. Bring their pressure to the value indicated in the passport (usually 0.2-0.25 atm). Do not try to pump them immediately into stone, as when pumping the floor, the pressure in the sides can increase slightly.
After the sides, we go to the floor of the NDND. The golden rule is: pump until the floor is hard, but not overdo it. The recommended pressure is usually 0.2 atm. If you use an electric pump, set this limit and wait for cutoffs. If the foot, rock until you feel elastic, but make sure that the hump does not form.
☑️ Boat pumping procedure
The final step is to pump the sides, and once the floor has spread out and taken its place, the pressure in the sides may have dropped, bring them to working condition (usually 0.25-0.3 atm). work pressure It is indicated for air temperature +20 ° C. In the hot sun, the pressure will increase, in the cold - will fall.
What to do if the floor is still soft?
If the floor remains soft after pumping to 0.2 atm, check the valve integrity and no punctures. Sometimes the softness is due to the design features of cheap models, where more pressure is required, but this is rare.
Table of optimal pressure for different elements
For user convenience, we have organized the data by typical pressure values. Please note that these figures are averaged and may vary by brand (see below).Flagman, South, Cayman Always consult the manufacturer's instructions.
| Element of the boat | Optimal pressure (atm) | Maximum pressure (atm) | Note |
|---|---|---|---|
| Borta (cylinders) | 0.25 | 0.30 | Control in the sun |
| Paul NDNDM | 0.20 | 0.25 | All the way to the stringers. |
| Keel (ballon-kielson) | 0.15 - 0.20 | 0.25 | To improve the course |
| Inflatable seat | 0.10 - 0.15 | 0.20 | For comfort. |
As you can see from the table, the pressure spread is small, but accuracy is important. Excess pressure in the NDND above 0.25 atm often leads to irreversible deformation of stringers and peeling off the floorboards from the sides. This is the case when the “porridge with oil” will not spoil, and the boat is easy.
Temperature factor: winter, summer and sun
Charles's Law says that when you keep a constant volume, the gases increase their pressure when you heat them up, and that's an axiom that every PVC boat owner should know: If you pump the boat in the shade at 20°C, and then you pull it out in the sun, where the temperature inside the cylinders goes up to 40°C to 50°C, the pressure can rise by 10-15 percent.
⚠️ Attention: If you leave a fully pumped boat ashore in direct sunlight even for 15 minutes, the pressure inside can grow so much that the seams can't withstand. Always blow a little air if the boat is unattended in the sun.
Winter fishing, by contrast, requires constant monitoring, and when you leave a warm garage (+20°C) in the cold (-10°C), the pressure in the cylinders will drop to almost zero, the boat will become sluggish, and the sides may collapse, in such conditions you need to have a pump for periodic pumping or pump the boat directly on the ice.
Compensation rule: in the heat, we blow air, in the cold, we pump it. The ideal pressure is 0.25 atm at ambient temperature at the time of getting on the water.
Common Mistakes and How to Avoid Them
The most common mistake is to try to pump the NDND to the state of a "drum": owners confuse the hardness of the bottom with high pressure, stringers and a stretch system give the bottom hardness, and the air only straightens the fabric, and excessive pressure makes the boat look like a banana, and it becomes difficult to operate it on the water.
The second mistake is sequence ingeneration, and some people try to pump the floor while the sides are still soft, and this causes the floor to burst out to the sides, and it can't fit right between the sides, and it creates folds that rub and spoil the look and durability of the product.
- ❌ Use of compressors from trucks: They're delivering air too fast and too powerful, you can miss the moment of pumping and break the seam in seconds.
- ❌ Pumping "in the eye": Without a gauge, you will not be able to assess the actual condition of the boat.
- ❌ Ignoring valves: dirt or sand in the valve will not allow you to reach the desired pressure or lead to etching of air.
⚠️ Warning: Never use industrial compressors without a gearbox and pressure gauge to pump BNDT, and these systems can reach 6-8 atmospheres, which will instantly tear a boat designed for 0.3 atm.
Post-use care and storage
The right pumping is only half the success, and after fishing, you need to build the boat properly, and you need to flush the air in the same sequence that you pumped it, but in the opposite order: first the sides, then the floor, and this will avoid valves getting stuck and tissue damage.
Before packing, make sure the boat is completely dry. Wet cloth in tightly folded condition is the perfect mold environment that destroys PVC and glue seams. If you can't dry the boat at home, try to at least wipe it dry and keep it rolled up for longer than a day.
How fast can I release my DND?
Open the valves and walk the boat, starting from the nose to the transom, and you can use the back of the pump (pump mode) if you have one, or just roll the boat gently, expelling air to speed up the process.
Frequently Asked Questions (FAQ)
Can I use a normal foot pump to pump my NDPD?
Technically possible, but it will require tremendous physical effort and time. NDNDM is large in volume, and single-cylinder pumps ("frogs") are inefficient for large volumes at low pressure.
Why did the pressure drop after the pumping of the sides?
It's a normal physical process. When you pump the NDND floor, it expands and it squeezes the interior space of the sides a little bit, or vice versa, the sides stretch. Once you've done all the work, just bring the pressure in the sides to normal.
Do I need to blow the air at night if the boat is on the water?
Yes, it must. At night, the temperature may drop, and during the day it will rise. If it is cold at night and hot during the day, a boat that is pumped up in the evening may burst in the afternoon.
What is the minimum pressure allowed for NDNDM?
The minimum pressure at which the floor is still performing its function and not being smeared under the weight of the fisherman is about 0.15 atm. Below this value, the boat loses driving performance and becomes dangerous to control.