Comparison Kolibri KM-300DL vs Kolibri KM-300

The type of bottom provided in the design of the boat.

All bottoms can be divided into flat and keel, each option has its own advantages and disadvantages. So, flat bottoms are relatively simple, inexpensive, convenient in shallow water (due to minimal draft) and allow you to go on planing with a relatively low engine power. On the other hand, the keel improves both manoeuvrability and directional stability, it allows the boat to effectively "cut the waves" at high speed and reduces the influence of wind. Thus, a flat bottom should be chosen for rowing or under a relatively weak motor for short distances; and the keel design is perfect for high speeds, powerful motors and long passages.

Both flat and keel bottoms can have different designs. In the first case, the options might be:

— Actually flat, it is also tension — the simplest bottom made of soft waterproof material stretched between the sides of the boat. The main advantage of this option is simplicity and low cost. In addition, the tension bottom is insensitive to minor damage: a small cut or puncture practically does not change its properties, does not affect the strength and seaworthiness of the boat. At the same time, the rigidity of such a bottom still turns out to be low, and for comfort it is desirable to use additional coatings with it.

— Flat inflatable(NDND). The so-called low-pressure inflatable...bottom is a bottom made in the form of a separate inflatable compartment. Such surfaces are noticeably stiffer than tension ones, which allows them to be used without additional coatings and simplifies the deployment and folding of the boat. The inflatable compartment provides additional comfort: it dampens the impact of small waves and plays the role of thermal insulation, the latter can be useful on land. In addition, this design increases the carrying capacity and provides additional buoyancy in case of damage to the main cylinder. The main disadvantages of inflatable bottoms are relatively high cost and sensitivity to damage. In addition, such a bottom reduces the actual volume of the cockpit, and its rigidity is still relatively low, and it can be difficult to maintain balance while standing on the NDND.

Keel bottoms, in turn, can have the following design:

— Inflatable keel. The simplest type of keel bottoms, in fact, is a flat tension bottom (see above), supplemented by a keelson compartment, which turns into a keel when inflated. The advantages of such structures are simplicity and low cost, the disadvantage is low rigidity, due to which the bottoms with an inflatable keel have to be equipped with additional hard coatings.

— Inflatable keel ( NDND). An analogue of a flat inflatable bottom (see above), which has the same set of advantages and disadvantages and differs in the actual presence of a keel. This design differs from the inflatable keel described above in that the entire bottom is made inflatable, and not just the keelson. This provides rigidity and eliminates the need for special coatings. On the other hand, keel boats with NDND turn out to be less stable than their counterparts with an inflatable keel, they sit higher in the water and ideally require additional loading to reduce draft; Yes, and such bottoms are somewhat more expensive than analogues with an inflatable keel.

— Fibreglass keel. Keel bottom in the form of a rigid part made of fibreglass or other similar polymer. Models of this design are called RIB (RHIB) — "rigid hull inflatable boats." They combine the advantages of classic and inflatable boats: the vessel does not sink, even when it fills with water "on the sides", and remains buoyant even when the tank is completely deflated. In addition, high rigidity provides reliable support for people in the boat and allows the use of even fairly powerful motors; thanks to the latter, fibreglass keels are extremely popular in powerboats (see "Type"). The disadvantages of this option, in addition to the high cost, include the impossibility of folding, which is why you have to carry such a boat on a gun carriage, and store it in a fairly spacious room.

The type of cover for the bottom provided in the scope of delivery. Coatings are mainly used to provide extra rigidity if the bottom itself is too soft; this is true mainly for flat tension bottoms and boats with inflatable keels (see "bottom type"). Specific options might be:

— Rack slant. Flooring of several wide transverse rails, usually connected by a flexible mount. Thanks to this fastening, the slate can be folded into an "accordion" for storage and transportation, while in working condition the coating still turns out to be quite rigid.

— Rigid plywood flooring. Rigid coating made of waterproof plywood, usually, typesetting — consists of several separate segments, and for storage and transportation is disassembled for compactness. Plywood coatings combine good rigidity and low cost, which makes them very popular. In terms of strength and reliability, they are somewhat inferior to aluminium decking, but in most cases this drawback is not critical.

— Rigid aluminium flooring. Type-setting coating of aluminium segments fastened together when installed in a boat. In general, it is similar to plywood (see above), but aluminium is more durable and reliable, and it is absolutely not subject to corrosion. On the other hand, this material is expensive, which is why it is much less common.

— Inflatable flooring (NDVD).... NDVD stands for “high pressure inflatable bottom”, however, this design should not be confused with an inflatable bottom (see “Bottom Type”): in this case, we are talking about a removable flooring. Due to the high pressure, such flooring turns out to be very rigid — noticeably stiffer than the bottom of the NDND type (although softer than plywood / aluminium coating). At the same time, the inflatable cover can be compactly folded during non-working hours, which ensures convenience in storage and transportation. Among the disadvantages of this option, sensitivity to damage can be noted.

— Without additional coatings. The absence of any coating in the scope of supply. Depending on the type of bottom (see above), this equipment may either mean that the boat does not require additional coating in principle, or that the flooring must be purchased separately. The second option is convenient in that you can choose the flooring at your discretion, without relying on the decision of the manufacturer.

The maximum engine power allowed for this boat.

The power limitation is primarily due to the fact that not every boat normally tolerates high speeds. In addition, powerful motors and weigh a lot, which puts forward appropriate requirements for the strength of the transom. So it is extremely undesirable to exceed the permissible power: even at low thrust, the structure will be subjected to abnormal loads, and full thrust can lead to a rollover or damage to the boat.

The number of separate compartments provided in the design of the boat's inflatable balloon. This arrangement increases the reliability and safety of the vessel: in the event of a puncture, air does not escape from the entire cylinder, but only from one compartment, the rest remain filled. Therefore, even the simplest modern boats have at least two separate compartments, and in the most advanced this number can reach six.

The more compartments there are, the safer the vessel in case of damage to the cylinder, but the more complex and expensive its design is. Therefore, this parameter usually depends primarily on the size of the boat — after all, larger and lifting models should be more reliable and lose less buoyancy in case of damage.

Note that the inflatable keel (if any, see "Bottom type") is also taken into account in this case, since in fact it is also a separate pressurized compartment: for example, if 5 compartments are indicated for a model with such a bottom, this means 4 sections in sides plus keel.

The density of the PVC fabric from which the boat is made.

The higher the density, the heavier the ship will be, other things being equal. In addition, it is generally accepted that a denser fabric is at the same time more durable, reliable and wear-resistant. However, much also depends on the characteristics of the production of a particular brand of PVC. As a result, the difference in performance between two boats with different densities may not be as significant as the difference in density itself.

The total weight of the boat with oars and decking (if any), but excluding the motor and additional attachments. The lighter the boat, the more convenient it is to carry, however, a small weight can affect either the price or the quality (compared to analogues). Weight also affects speed characteristics — a lighter boat is easier to accelerate to high speed with the same motor power; however, do not forget that these characteristics also depend on the material, the shape of the bottom and many other parameters.