The most frequently asked question is - are there any advantages to the catamaran structure of boats, compared to ordinary pitching boats?
And if so, why are inflatable keel boats much larger than catamarans? Let's deal with you completely in this fundamental issue.
1. Principles of movement.
BOATHOUSE catamarans have two integral inflatable cylinders of a special hydrodynamic shape, the bottom and the transom, which do not touch the surface of the water. Thus, the catamarans go on two cylinders, without touching the bottom of the water, with minimal resistance.
Keel boats have conditionally V - shaped bottom (due to inflatable keel), submerged in water, a balloon and a transom, the lower part of which is also located in the water. Thus, the area of contact with water in the keel boats is much larger.
What happens when the BOATHOUSE catamarans move: the catamaran pushes the water out with an acute nose part of the cylinders with a low angle of attack and smoothly leaves it at the end of the cylinders. The higher the speed, the stronger the lift force pushes the catamaran out of the water. Due to this, BOATHOUSE catamarans can go at any speed - from minimum to maximum - without transient conditions. And since the BOATHOUSE cylinders have minimal resistance in water (a smooth rise from the beginning of the cylinder to its maximum diameter is almost one and a half meters), then the speed characteristics of the catamarans are simply excellent. That is why, for confident movement from a minimum speed up to a speed of 25 km per hour, a light and economical motor is enough, with a capacity of up to 6 hp, and on the largest models up to 15 hp. Over 25 km / h a large enough resistance: the lifting force is trying to push the catamaran out of the water, but it does not have a flat surface for going to gliding. Therefore, the use of powerful engines on the Boathouse displacement catamarans is pointless. For them, it is advisable to use low-power motors for comfortable and very economical movement.
Consider the movement of a pitching boat. At low speeds, an inflatable keel boat with its front “blunt” part pushes water in front of it. With increasing speed, from about 7 - 8 km per hour, the bow of the boat rises above the water, and the transom deeper sinks into the water - so much water resistance. The boat must "jump" on the water to reduce resistance. At a speed of 10 - 12 km per hour, the bow of the boat is already very strongly raised up and it is almost impossible and unsafe to go in this mode. And now a powerful engine is needed to push the boat out of the water and go into the gliding mode, which starts from 18 to 20 km per hour or more. Why is all this happening? A blunt nose, a large area of contact with water and, especially, a transom in the water create tremendous resistance until the boat is pushed out of the water with a motor power and switches to a gliding type of movement. But in order to bring it to the glider, powerful engines are required. Moreover, each person in the boat very much takes the engine power. And it often happens that having put one more person in the boat, the engine power is not enough to take it to gliding. And then the keel boat is forced to push a wave at a speed of up to 10 km per hour.
Advantages of Boathouse displacement catamarans:
- easy travel and excellent speed at the oars, under the sail, under the electric motor and petrol engines of low power;
- the length of the catamaran does not affect the speed characteristics;
- the possibility of using very large models of catamarans under low power engines, under sail and even at oars;
- ach crew member slightly reduces the maximum speed - by 0.7 - 2 km / h, depending on the model;
- use of the entire speed range - from minimum to maximum;
- safety in all speeds;
- cost savings on the purchase of a lighter engine;
- economical movement: 2-3 times less fuel consumption, compared to the keel boat.
Disadvantages of Boathouse Displacement Catamarans:
- - less maximum speed on powerful motors than keel boats;
- - a lot of spray from the cylinders at high speeds.
Advantages of inflatable keel boats:
- - good maximum speed on powerful motors.
Disadvantages of inflatable keel boats:
- - slow movement on oars and on low power motors;
- - a comfortable speed range of 10 to 20 km / h is not available;
- - limited boat size and passenger capacity;
- - unsafe transition from displacement to gliding, especially in the case of a sharp turn;
- - the impossibility of access to gliding in shallow water (during the transitional movement of the stern of a boat with a motor very much deepens into the water, reducing patency);
- - the need for a powerful engine, the cost of which is several times higher than the cost of the boat itself;
- - high fuel consumption.
2. Manageability, stability, exchange rate stability, behavior "on the wave" and cross.
The handling of Boathouse catamarans is smoother and completely safer than keel boats. Especially you need to be careful with a sharp acceleration and exit to planing. With a sharp acceleration, keel boats greatly lift their bow, limiting visibility, and greatly increase the draft, deepening the stern with a motor. Catamarans do not have these phenomena - acceleration is absolutely even. At high speeds in turns, the boats glide out of the turn, the catamarans go along the rails - along a precisely defined path. Therefore, the handling of a keel boat requires certain skills and care, and the handling of a catamaran is easier, more accurate and safer.
Boathouse catamarans stand on the water on two cylinders, and keel inflatable boats with a V-shaped bottom. It is clear that catamarans are much more stable, or, correctly speaking, stable than keel boats. You can safely walk on the flat deck of an inflatable catamaran. If several people sit on one side of the keel boat, this can cause the boat to tip over. If on the catamaran the whole team (at least 10 people) will sit on one cylinder, then in calm water they will not be able to turn the catamaran, even if they want to. This quality allows you to safely swim with a catamaran, engage in spearfishing and diving.
The directional stability of the vessel directly depends on the length of the hull and the elements stabilizing the movement: for keel boats it is the keel, for BOATHOUSE catamarans - cylinders with redans in the front and stabilizers of directional stability in the rear. Therefore, due to its structure and long length, catamarans have better directional stability (moving in a straight line without taxiing) than inflatable keel boats, and even more so flat-bottomed boats. On travel, this quality is especially valuable.
Many people know how inflatable keel boats behave “on the wave”: gliding is impossible, they completely repeat the movement of water, and meet the wave with a “blunt” nose. It’s dangerous to turn boats sideways to the wave - you can really roll over.
The behavior of the catamaran "on the wave" is completely different. BOATHOUSE catamarans meet the wave with a sharp nose, and they can choose any speed mode of movement according to their comfort. In addition, Boathouse catamarans do not touch the bottom of the water even when fully loaded. Therefore, on the waves, cylinders work like shock absorbers. Thanks to their excellent stability, catamarans can even go sideways to the wave. Of course, it all depends on the height of the wave and common sense. Still, there is a general rule - the longer and stiffer the hull of the boat, the larger the diameter of the balloon, the better and safer the boat behaves on the wave. The largest Boathouse catamaran model is 8.5m long, 2.6m wide and 65cm in diameter. Have you seen an inflatable keel boat of this size?
Passability of the vessel through the places of rivers and lakes overgrown with plants, along shallow water and along mountainous rapids, provides several indicators: draft, contact area with water and the protection of the lower part of the boat under water.
BOATHOUSE catamarans have a contact area with water much smaller than keel boats. Therefore, passing through overgrown places, catamarans simply push apart the vegetation with pointed tanks and pass it under the bottom, which does not touch the water surface. Keel boats, pushing water in front of themselves while moving, also push in front of them, like a bulldozer, a bunch of plants that can be overcome only by hitting back and continuing to move along a different trajectory.
The draft at the keel boat and the catamaran is about the same and, it would seem, in shallow water both will pass equally. But no, especially against the tide. The fact is that on all rivers in places of shallow water, as a rule, a fairly strong current. So, to overcome it, the keel boat needs to add speed to the engine, therefore, the bow of the boat moves up, and the transom with the foot of the engine and the screw - down and - rests on the bottom of the river. You can, of course, overcome the shallows on the glider (then the draft at the boat is minimal), but at high speed you can easily damage the engine or, in the best case, a screw, hitting a fuel tree or stone. In this situation, the catamaran runs the same aground at low speeds, but can also pass at medium speed - its nose “does not bulge”, and the feed with the transom does not fall under water.
As for the rapids and mountain rivers, everything is clear here, the catamaran is a “water SUV”. In a keel boat, the most vulnerable lower part is the lower part of the transom, which can be damaged on the very first stone. In BOATHOUSE catamarans, the lower part of the cylinders is additionally protected along the entire length - that is, it is quite difficult to break through the bottom of the cylinder, and the transom and bottom are above the surface of the water, even when fully loaded. Therefore, on catamarans you can safely move along rapids and mountain rivers to the third category of difficulty. The main thing is not to let boulders protruding from the water between the cylinders - you can damage the front frame and transom.
3. Assembly-disassembly, weight, carrying capacity and passenger capacity.
We will not describe the assembly process, especially the installation of hard flooring on keel boats. It ends, as a rule, with obscene expressions of the owners and persons wet from sweat. The fundamental difference is that the rigid flooring in keel boats needs to be inserted under the cylinders into the stringer, and for BOTHAUS catamarans, simply put it on the bottom between the cylinders, just above the middle. And then, when pumping the cylinders to the desired pressure, the clamps firmly clamp the floor between the cylinders, transom and frame. That is why the assembly of BOATHOUSE catamarans is one of the easiest and fastest. Especially if the main air is pumped into the cylinders with an electric pump powered by the car’s cigarette lighter.
If we compare the weight of keel inflatable boats with rigid flooring and Boathouse catamarans, with similar passenger capacity, then catamarans, on average, will be 25% lighter.
Carrying capacity and passenger capacity are interrelated concepts that depend on the diameter of the cylinders and the length of the vessel. No one wondered why the largest inflatable keel boats are about 4.5 m long and have a carrying capacity of about 800 kg? Everything is very simple: to bring such a volume and weight to the glider, you need an engine 25 - 40 hp. How many people will fit in a boat 4.5 m long? Six, maximum eight. There is no need to talk about any kind of comfort at all: they sit either on wooden benches or on cylinders. And if the motor power is not enough to bring the boat to planing, then the speed will be about 10 km per hour. And motors of even greater power already require other transom materials, a different boat structure and remote steering. This is a completely different budget and a different design. For those who do not know how much outboard motors cost, we give average data for Japanese 4-stroke engines: 5-6 hp. - about $ 1400, 15-20 hp - about $ 3200, 25-30 hp - from 4000 $.
Boathouse catamarans have a completely different experience. 5-6 meters long is the average length of catamarans. If we take, for example, the six-seater model Sea Fisher 550, with a cylinder diameter of 50 cm, then it weighs 20% less than an inflatable keel boat, 4.5 m long. The optimal engine power for this catamaran is 6 hp. If you need a speed of more than 20 km / h with full load - we put an engine with a capacity of 15 hp. If in the largest catamaran Sea Fisher (8m long) place 10 people in personal soft chairs and install a motor with a capacity of 15 hp , the speed will be about 20 km per hour.
Let's conduct a simple experiment: we put a 6 hp engine on the Sea Fisher 800 and we comfortably accommodate 10 people, and in a 3-meter keel boat we will plant only 3 people, and also install the same motor. Catamaran will easily overtake a boat!
4. Safety and comfort.
By passive safety, which is ensured by the number of pressurized compartments, the presence of molding valves, the density and quality of PVC fabric, keel boats and catamarans are approximately the same. But! BOATHOUSE catamarans have much better stability: if the whole team sits on one side (balloon), the catamaran will not roll over. The design of the BOATHOUSE catamarans is unsinkable: even at full load, the bottom does not touch the surface of the water. Therefore, even if the wave completely covers the catamaran at full load, it will remain on the surface (there is a buoyancy margin), and all water from the catamaran will go through the drain valves. If we take into account the “off-road” qualities (passability) of catamarans, excellent wave behavior and absolutely safe control, then BOATHOUSE catamarans are much safer than keel boats.
The ship's comfort is determined by many parameters:
- - the ability to choose a comfortable speed;
- - passive and active safety;
- - Good easy handling and directional stability;
- - flat deck and spaciousness;
- - the presence of storage compartments and lockers;
- - comfortable fit, quantity and variety of additional equipment for fishing and recreation;
- - the ability to be on board for a long time without signs of fatigue.
It is clear that there is no need to talk about the comfort of keel inflatable boats at all. Even tuning does not greatly change the situation: it becomes more convenient, but not by much. Of course, when compared with the BOATHOUSE catamarans. The level of comfort provided by the BOTHAUS catamarans to their owners was previously considered impossible on lightweight inflatable structures!
5. Price, efficiency and reliability.
The cost-effectiveness of catamarans, in comparison with keel boats, we have already considered above. In terms of fuel consumption, BOATHOUSE catamarans are 2-3 times more economical than keel boats. The average fuel consumption on inflatable keel boats is comparable to automobile - about 10 liters per 100 km, if the boat does not exceed 3 people. BOATHOUSE catamarans do not have such a critical dependence on the load and the number of passengers on board. On 10 liters of gasoline, a catamaran with two or three people can go more than 300 km, and an 8-meter BOATHOUSE catamaran with six passengers and things to go on 10 liters of fuel can go more than 200 km! If you went fishing for a few hours, the difference is not very noticeable, but if for a few days or weeks ....
Price. It is the issue of price that is important, and for many - a priority. And many, without going into details and not taking into account everything that we examined in detail above, fall into the trap. Take the price of a keel inflatable boat with a certain passenger capacity and compare with the price of a similar Smart-Fisher catamaran (42 cylinders), Fisher (45 cylinders) or Sea Fisher (50 cylinders). And here is the disappointment: the catamaran is 100-300 dollars more expensive. Why overpay? “Well, I’ll sit on the spot somehow, well, I won’t go out into the water, I’ll gently gas ... Well, think about fuel consumption - how much will I drive there? After all, they still somehow go on such boats ?! ”
The choice is made. And then it begins, “Oh my God, I didn’t know what to buy such a motor, but how much does it cost ?!” And here the saved 200 dollars turn into overpaid 1,200 dollars and even more! Remember the proverb - “avaricious pays twice”?
The production (manufacture) of BOATHOUSE catamarans is more complicated and more expensive than the production of keel boats. And only the very best materials are used for catamarans: German PVC fabrics, marine plywood, airdeck and aluminum. Everything is designed for a long (over 10 years) and trouble-free operation. Therefore, a catamaran always costs more than a keel boat of the same passenger capacity. But we do not buy a car without a motor? We always look at prices for cars with different engines, and choose a well-managed, economical, comfortable, safe and, preferably, passable car. The same situation should be with a water vehicle. How can you not think about it ???
Now you can answer the most frequently asked question: “are there any advantages of a catamaran boat structure compared to ordinary keel boats? And if so, why are there many more inflatable keel boats than catamarans?
We hope so. And we, the BOATHOUSE team, will help you.
Firstly, this design of catamarans, despite the obvious simplicity, was invented only in 2012, as evidenced by the Patents for inventions. This was made possible thanks to modern high-tech materials and with the involvement of professional travelers, athletes, highly qualified specialists and the best designers.
Secondly, many still simply do not know that there are such boats - BOATHOUSE catamarans - with such characteristics and such operational indicators.
Thirdly, when choosing a boat, they pay attention only to the price of the boat without a motor, and do not consider the final cost of the kit - with a motor and additional equipment. And without considering that modern water transport is designed for many years of operation.
Fourth, BOATHOUSE is developing independently without attracting external capital. This means that advertising and promotion costs are minimal. Mainly due to the positive feedback from owners of Boathouse catamarans. Some of our customers prefer only BOATHOUSE catamarans and have up to 5 different models!
And fifth, simple human inertia or conservatism: to be wary and distrustful of something new, progressive. Cars have already proven that new models are better than old ones. How many people today want to ride a Zhiguli and a Muscovite? Now the next step is water transport!
"Having BOATHOUSE - you live with pleasure."