Comparison Bark BT-310SD vs Bark BT-310D

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 infla...table 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.

— Steering. This feature means that the boat is equipped with a steering wheel and special rods, which, when the steering wheel moves, turn the screw (s) in the direction necessary for turning; next to the steering wheel is usually also a throttle knob. Steering is found exclusively in RIB boats with fibreglass keels (see "bottom type"); it significantly affects the cost, but this is offset by a number of practical advantages. So, the steering wheel is usually located approximately in the middle of the cockpit, from where the view is much better than from the stern (especially in planing mode, when the bow of the boat is very high); and the helmsman sits upright at the helm, facing forward—more comfortable than the half-turn position when steering through the outboard two-wheel tractor.

— Water release valve. The presence in the design of the boat of a separate valve for draining water from the cockpit overboard. In many models, such a valve can be used both on the shore and on the move, and anyway, it greatly simplifies the removal of water that has got inside — otherwise it would have to be scooped out, or even turn the whole ship over.

— Carrying handles. The presence in the design of the boat of special handles for carrying the boat in an inflated position. By themselves, the cylinders used in modern boats usually have a smooth surface with a...minimum of protruding parts, as a result, they are difficult to grasp. Therefore, for additional convenience, separate handles are provided — they significantly simplify tasks such as pulling the ship ashore.

— Olocks. The presence in the design of the boat of oarlocks — special devices on the sides, in which oars can be installed when rowing. Each paddle is attached approximately in the middle and can move in a vertical and horizontal plane. Such an installation provides additional convenience and reduces the load on the rower's hands — otherwise you would have to work with only one oar, and constantly keep it on weight and risk releasing it into the water. However rowing with the use of oarlocks involves the position of the rower with his back forward, and is also poorly suited for some situations (for example, for manoeuvring in floodplains); but these devices usually do not interfere with rowing in other ways.

— Rym. The presence in the design of the boat of a ring — a special fastening for ropes, usually installed in the bow. Such a mount can have a different design and purpose. So, the classic eye is made in the form of a ring and is used both for the anchor rope and for the towing rope; but there are also “purely anchor” options — in the form of a stand with a groove through which the rope is passed (so that it is fixed in the right place and does not rub against the sides once again).

— Bulwark. The presence in the design of the boat of a bulwark — a barrier installed above the main cylinders; usually, such a barrier itself is an additional balloon. The bulwark performs several functions. The most obvious of these is an increase in capacity, comfort and safety: due to the increased height of the sides, the risk of objects or people falling out of the cockpit is reduced, more overall cargo can be placed there, and less spray gets through such sides. Also, the bulwark increases the longitudinal rigidity of the hull, besides, its volume can be separated from the main cylinders; All this has a positive effect on overall reliability. This feature is found mainly among high-end models designed for difficult conditions and long stays away from the coast.

— Fender bar. Acts as a shock absorber. The beam is glued along the perimeter of the boat, along the line of contact of the side with obstacles and serves as a fender when mooring the boat to wooden or concrete piers. It can be made of rubber, PVC, plastic and other materials. Of course, its installation on a boat carries some negative aspects. So, the right timber makes the boat somewhat heavier and worsens its twisting. Such a boat is more difficult to transport and store.

— Water breaker. A water chipper is a part of the fender — a strip of thickened material on the outside of the sides. This strip provides protection when mooring to a jetty, driving through aquatic vegetation, etc. And the water chipper is a “visor” bent down along the fender; its purpose is to prevent water from entering the cockpit of the boat, especially when moving at high speed.

— Handrail cable. The handrail cable is installed on the mounts on the outside of the sides and "encircles" them, in whole or in part. There are many uses for this feature. For example, a person overboard can hold on to the cable — this is easier than clinging to the cylinders themselves or other devices. Also, the cable can be used as a replacement or addition to the carrying handles (see "Additionally"), as a place for attaching various equipment, etc.

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 dimensions of the inflated boat in length and width, along the outer edges (excluding oars, motor, etc.). This parameter allows you to estimate how much space the vessel will occupy in the working position. In addition, the first size value — length — indicates other parameters: the larger it is, the better the boat is suitable for gliding and, usually, its capacity is greater (see "Number of seats").

Dimensions of the boat when fully deflated and collapsed. The more compact the folded boat, the more convenient it will be in storage and transportation; at the same time, too small, in comparison with analogues, dimensions can indicate a small thickness of the shell and relatively low reliability.

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.