When you look at a small vessel, especially a boat designed for sport rowing or kayaking, an inexperienced observer may notice specific outboard designs that resemble narrow floats or brackets. These elements often raise questions for beginners trying to understand the terminology of water sports and shipbuilding. In the professional environment, they are called boules, and they play a critical role in the balance and stability of the vessel, especially in extreme operating conditions.
The presence of such elements on board is not just a decorative device or a tribute to fashion, but the result of many years of evolution of engineering thought aimed at improving hydrodynamics. What are boatboat bulls?It's not just for rowing athletes, but also for owners of PVC inflatable boats or metal boats planning upgrades, and it's a fundamental change in the behavior of the vessel on the water, allowing you to reach speeds and rolling angles that would not be possible on a standard hull.
In this article, we will discuss in detail the design of the boules, their physical principle of operation and the effect on stability. You will learn why the installation of boules can be a decisive factor in saving the crew in high winds or a sharp shift in the center of gravity.
Definition and functional purpose of boules
The term "bul" is derived from the English word "outrigger", although in Russian tradition, especially in the context of kayaks and canoes, the concept of "bul" is often used as part of the design of a remote stabilizer. In fact, it is a rigid or inflatable structure, carried overboard the vessel on special beams (outriggers), which serves to increase the width of the support without increasing the width of the waterline hull itself.
Unlike conventional floats, which can be simply tied to the side for extra buoyancy, bulge They're integrated into the overall power circuit of the vessel, and they create a lever that counteracts the heeling moment, and when the boat starts to tilt under the wind or the movement of the rower, the bull is submerged in the water, creating a huge lift on the shoulder of the lever, which puts the boat back upright, and this allows for narrow, fast hulls that would be extremely unstable statically.
There is a misconception that bullies are exclusively for racing kayaks. In fact, the principle of outriggers is widely used in Polynesian pies, modern catamarans and even some models of trolling fishing boats, where a stable platform is required to install tackles. Buhl design It can range from a simple sealed cylinder to a complex hydrodynamic shape that minimizes water resistance.
Etymology of the term
In English, the design is called Outrigger, which literally translates as "removable board", the term "bul" in Russian is more often associated with a specific element of the stabilizer or the float itself, brought overboard, especially in sports rowing.
It's important to understand the difference between static and dynamic stability. Booles are primarily dynamic when the boat is already tilting; when calm, they may not even touch the water, which reduces the resistance of the hull when it's in straight motion. hood (rollover)
Design features and materials of manufacture
Modern bules are made of materials that combine minimum weight and maximum strength. carbon (carblasty) and fiberglassThese composite materials allow for thin-walled but rigid structures that do not deform under load. Budget models or amateur PVC boats can use inflatable elements made of high-strength PVC-coated fabric, but their rigidity is much lower.
Structurally, the boulder consists of the float itself and the anchoring system (outriger beams). The beams must be absolutely rigid, since any deformation will lead to a loss of stabilization efficiency. The mounting to the boat hull is carried out through special brackets, often adjustable, which allows you to change the outlier and angle of its inclination relative to the water surface.
- 🛶 Hard bules: They are made of carbon fiber foam or fiberglass, providing maximum stability and minimal resistance, but require careful storage and transportation.
- 💨 Inflatable bules: They are made in cylinders or toruses, easily transported in assembled form, but are subject to punctures and can change volume depending on the temperature of the water and the sun.
- ⚓ Hybrid systems: They combine rigid frames and inflatable tubes, and they're popular on expeditions where versatility and field-repairability are important.
Special attention should be paid to the anchorage points. Because the boulder perceives enormous loads when rolling, their installation on the hull must be strengthened. Wood boats use cut-in spigates or additional stringers, fiberglass boats use stickers made of multilayer laminate, and in inflatable boats - special shackles or hard inserts. Weak attachment can lead to the tear of the boulder at the most inappropriate time.
When choosing boules for self-installation, pay attention to the presence of drainage holes at the bottom of the float. They allow water that gets inside when hit by a wave to flow quickly without creating excess weight and resistance.
Influence of Booles on Stability and Driving Performance
The installation of boules is a major change in the physics of boat movement, and this is particularly true. transom stabilityA narrow racing kayak without boules has very little initial stability moment -- slightest shifting the weight of a rower can lead to a coup. With boules taken out, the metacentric height of the vessel increases, making the boat almost unstoppable under operating rules.
However, stability is a cost. The elements that are carried overboard create additional drag. In straight-line motion, if the boules are too deep or in the wrong shape, they can significantly slow down, so the correct setting is that when they are calm, the boules only slightly touch the water or are 1-2 cm from the surface.
Booles also affect handling. When turning a boat, the outer boolean can burrow into the water, creating the effect of braking one side, which makes it easier to turn, but requires the rower or steering officer to coordinate more. In a strong wave, the presence of booleans allows you to develop more speed, since the rower can not waste energy on maintaining balance, but completely focus on rowing.
There's a concept called "boole efficiency," which is calculated as the ratio of the recovery moment to the resistance that is created. Modern computer simulations allow us to calculate the optimal shape of the boule cross section so that it enters the water smoothly without creating shock loads and spray that could interfere with the rower. Aerodynamics It also plays a role: at high speeds, protruding beams can create sailing, which must be taken into account when side winds.
Types of Booleans: Comparative specifications
Depending on the purpose of the vessel and the conditions of navigation, different types of boules are used. The choice of a particular model depends on whether the boat will be operated on the calm water of the lake, on a rough river or in the surf. Below is a comparative table of the main specifications of the different types of remote stabilizers.
| Type of boulder | Materials | Principal appointment | Advantages |
|---|---|---|---|
| Sporty (Oar) | Carbon/Foam | Kayak rowing | Minimum weight, ideal hydrodynamics |
| Tourist | Glass-plastic/Inflatable | Long-distance hikes | Universality, maintainability |
| Fishing | Aluminum/Plastic | Trolling, parking lot | High load capacity, stability |
| Expeditionary | Composite/Inflatable | River rafting | Impact resistance, possibility of replacement |
Sports bulls used in Olympic rowing represent the pinnacle of engineering. They are customized for each athlete and for a particular boat. Their shape can be asymmetrical to compensate for the stroking features. At the same time, fishing bulls are often made more massive to withstand the weight of the fisherman standing in the boat and heavy equipment.
The choice of the type of boule should be based on priority: if you want maximum speed, choose rigid carbon models with minimal immersion; if safety and versatility are important, inflatable or composite versions of increased volume are preferred.
Adjustable bulges, which allow you to change the angle of attack and depth of immersion directly on the water, are especially relevant for boats that are used by different crews or in changing weather conditions, and the ability to quickly adapt the configuration of the vessel provides a significant advantage in competition or difficult navigation.
Rules for installation and setting of remote supports
Mounting boulders on a boat is a process that requires precision and understanding of the mechanics of the process. Incorrect installation may not only not improve the performance of the vessel, but also make it dangerous for operation. The first step is always to mark the hull anchorages, they must be symmetrical and be at a level where the crew's center of gravity creates maximum heeling moment.
The adjustment process begins with adjusting the height. As mentioned earlier, in a static position (when the boat is flat), the boules should not create additional wave or resistance. The optimal is a gap of 1-3 cm to the water. When the boat rolls 10-15 degrees, the boulder should go into the water, starting to work as a stabilizer. If the boulder is immersed too deep all the time, the speed will drop, if too high, it will not have time to work before it tips over.
☑️ Checking the installation of boules
⚠️ Attention: It is strictly forbidden to weld or glue the mounts of boules to the thin side of the boat without the use of reinforcing linings (pyataks). Local load at the mounting point can lead to depressurization of the hull or destruction of the side under the influence of a lever.
After the physical installation, you need to do a test. You need to start in calm water, gradually increasing the angle of roll. You need to feel the moment when the bull starts working. It needs to do it smoothly, without sudden jerks. If the boat pulls sharply to the side when it enters the water, then the angle of installation or the shape of the bull requires correction. It also checks the reliability of fixing all bolts after the first series of swims.
Operation, maintenance and security
Boolean boats require a special approach to operation. Protruding parts dictate increased caution when approaching berths, other vessels and shallow waters. The risk of damaging or catching the boolean is much higher. Therefore, maneuvering should be smoother and the turning radius wider than in a conventional boat, especially in narrowness or in strong side winds.
Boolean maintenance involves regularly inspecting the surface for cracks, chips or scuffs. In carbon-based models, even micro-cracking can cause the structure to be layered under load. Inflatable elements require a check of the pressure and integrity of the valves. After each release to salt water, the boolean must be washed with fresh water to prevent corrosion of metal attachments and degradation of materials.
- 🔍 Visual examination: Before each exit, check the integrity of the fasteners and the absence of visible damage to the surface of the boule.
- 🧼 Cleanup: Remove algae and dirt that can disrupt hydrodynamics and increase the weight of the structure.
- 🔧 Climb: Periodically check the tightening of bolts, as vibration when moving along the wave can weaken the connections.
⚠️ Attention: Don't use the boules as supports for boarding and disembarking. Although they seem solid, the lateral load on the kink created by a person's weight can exceed the calculated load and cause the beam to break or the mount to break off from the hull.
Storage in winter
Hard boules are recommended to be stored horizontally on a flat surface or in suspension to avoid deformation from its own weight. Inflatable elements are better to be slightly lowered and stored in a warm room, avoiding direct sunlight.
The safety of the crew depends on the serviceability of the boules. If you hear a characteristic crackle or feel vibration coming from a remote structure during rowing, you should immediately stop driving and check the condition of the system. Ignoring these signals can lead to loss of stability at the most critical moment. Remember that the boules are your main safety element, and their reliability should not be in doubt.
FAQ: Frequently Asked Questions About Boat Bules
FAQ: Frequently Asked Questions About Boat Bules
Can I install the boules on a conventional PVC inflatable boat?
Yes, it is possible. There are special PVC boat tuning kits that include inflatable bules and rigid bracket arcs. However, it is important to consider that regular boat cylinders may not withstand the load on the anchoring points without additional reinforcement (shaft timber).
How much does the boat speed decrease?
When properly adjusted, when the bulae are not submerged in water when driving directly, the speed reduction is minimal (less than 5%) and is mainly due to the aerodynamic resistance of the beams. If the bules are constantly dragged through water or have a large cross-sectional area, the loss of speed can reach 15-20%.
Do I need to register a boat with boules in GIMS?
The installation of boules by itself does not change the classification of a vessel unless its load capacity or sailing area (if it is not a sailboat) increases to the limits that require registration. However, if the boules are a fixed part of the structure and significantly change the dimensions, this may require changes in documents. In most cases, small craft do not need this, but consultation with an inspector will not interfere.
Can you make a boulevard yourself?
It is technically possible to make PVC tubes from large diameter or sealed containers by attaching them to aluminum pipes. However, it is difficult to create an efficient hydrodynamic shape and reliable anchorage at home. Homemade bules are often highly resistive and may not be safe. For amateur use, it is better to purchase production models.