8  persons + 1500 kg

Description (download PDF presentation)

High-speed amphibious small hovercraft Neptune 23GRP is designed to carry up to 8 passengers + 1.5 tons of cargo. The vessel is a small-sized cargo-passenger version of the Neptune 23 hovercraft and is designed to transport passengers and cargo across water bodies in summer or winter, including with short-term access to shore. 

The boat is able to overcome smoothed ledges up to 80 cm high and not smoothed — up to 55 cm. The boat can reach speeds of up to 80 km/h on water.
Operation is permitted at outdoor temperatures from -40 ° C to +30 ° C and maximum wind speeds of up to 12 m / s at any time of the year during daylight hours. 

The hovercraft in all cases of loading can be operated in water areas, with waves of no more than 1.2 m 1% security. The boat is allowed to move at the specified wave both in the hovercraft mode and in the displacement mode. When driving on ice or snow-covered surfaces, operation is allowed in reservoirs of all categories. It is allowed to operate on any other flat hard surface, on the extreme shallow water and swampy surface.

Main dimensions and characteristics

Overall length of the hull, m 11.8
Extreme breadth of the hull (with hinged sections), m 4.3
Cushion height (clearance), m 0.75
Passenger-carrying capacity, people 22
Minimum crew, people 1
Payload, t 2.1
Service speed (on water), km / h 45
Maximum speed (on water), km / h 80
Service speed (on ice), km / h 50
Fuel reserve, l 400
Service fuel consumption on water, l / h 35
Endurance of fuel reserve, h 12
Safe wave height, m 1.2
Supervision (Option 1) STATE INSPECTION OF SMALL VESSELS (SISV), vessel of special design up to 12 seats (THE HOVERCRAFT)
Supervision (Option 2) River register, small up to 12 places, category * 3

The hull 

The ship’s hull is watertight, divided into 7 watertight compartments by 7 watertight bulkheads.
Sheet and profile rolled products made of aluminum alloys are accepted as the material of the main hull, set, and foundations. Sheet metal is used for the amg5m brand, ALL-UNION STATE STANDARD 21631-76. Profile rolled products of the AMg6M or D16T brand according to ALL-UNION STATE STANDARD 8617-75. The hull of the hovercraft is riveted (with the exception of small parts made by welding). The outer contour of the boat and the corresponding transverse bulkheads are impermeable. The impermeability test is carried out in accordance with the diagram and test table. Protection of the hull against corrosion is provided by the use of aluminum-magnesium alloys that are resistant to corrosion in river and sea water. In marine hulls, D16 alloy is replaced with amg. Additionally, it is planned to paint the exterior and interior surfaces of the housing with paint and varnish materials.


The passenger compartment of the hovercraft is divided by an impenetrable partition into two parts: front and rear. The front part is equipped with two soft passenger seats, including one for the captain. Behind the armchairs there are two folding seats on lockers and a folding sofa for four people. When unfolded, two people can sleep on the sofa.

In the rear section of the cabin, along the sides, there are six lifting seats that can be lifted to the side, creating free cargo space. Seat covers, floor covers and interior space are finished with corrugated metal, which allows cleaning the interior of dirty cargo. The arrangement of armchairs and sofas is subject to change. There are options with soft seats for all passengers, with folding berths and a table, with a crane-manipulator, with a toilet, with a loading platform and winches. The deckhouse is made of a three-layer structure, the middle layer of which is insulation. The outer layer is made of fiberglass based on polyester resin with a reinforcing material made of fiberglass, coated with a colored resin (gelcoat). The middle layer is a honeycomb filler. The inner layer is made of fiberglass, pasted over with sewing – pile fabric or imitation leather.


Two engines of the American brand Cummins ISF 2.8, with a capacity of 150 hp each, are installed on the hovercraf. An increase in engine power up to 175 hp is possible. by increasing the maximum crankshaft speed. It is also possible to install IVECO (FPT) engines with a power of 197 hp. A four-stroke, four-cylinder, electronic Common Rail diesel engine with in-line cylinders and common crankshaft pistons with one overhead camshaft.

The engine has a closed-type forced circulation liquid cooling system. Combined lubrication system: under pressure and spray. The Kamins 2.8 (Cummins ISF 2.8L) engine is installed on vehicles manufactured by OJSC GAZ, in particular, on commercial vehicles of the GAZelle Business and GAZelle NEXT families. Due to its prevalence, the engine is well known to services, and spare parts and consumables for it are not expensive and can be easily found in stores.

Today we can safely say that this engine is the most widespread commercial diesel in Russia. The engine is equipped with low temperature starting aids. An electric coil is provided to heat the air in the intake manifold. The fuel filter is also electrically heated. The Cummins ISF 2.8 engine has very low fuel consumption. The engines are standardly equipped with a turbocharger with an intercooler, that is, with pre-cooling of the air supplied to the charge.

Thanks to the use of turbocharging, it was possible to provide high power and torque with a sufficiently small volume. At the same time, the presence of a turbine does not impair the efficiency of the engine – its fuel consumption per vehicle ranges from 8.5 to 10.3 l / 100 km, depending on the speed and operating mode. The engine has a traditional design. It is based on a one-piece cylinder block (made of gray cast iron) and a cast head; inserted milled liners are used in the block, which facilitates cylinder repair.

The crankshaft is also made of gray cast iron and is integrated with the crankshaft position sensor pulley and toothed disk. The camshaft is one, located at the top. The motor has 16 valves (4 per cylinder), made of heat-resistant steel, their rods are additionally chrome-plated. The valve drive is traditional, through rocker arms. Interestingly, all valves have the same design, but are not interchangeable. Timing drive – chain. The engine is equipped with Bosch Common Rail fuel equipment, the fuel injectors are top-mounted, they are installed in the central part of the cylinder.

This solution has greatly simplified the engine without significantly degrading its performance. In general, the Cummins ISF 2.8 is a simple, reliable and unpretentious engine with good characteristics and adapted for operation in Russian conditions.

Thanks to the design features, a simple device and the use of time-tested solutions, it was possible to achieve a high resource – the manufacturer claims an engine resource of up to 500 thousand km (for a car), in practice, the engine can last longer with proper operation and maintenance.

The engine is currently being manufactured at the Cummins FOTON joint venture in China.

Type of engine 4-stroke 4-cylinder Cummins ISF 2.8s 3129T
Number of engines, pcs. 2
Power, h.p. (kw) 150(110) х2
Maximum speed, rpm 3200
Working capacity, cubic cm 2781
Compressive ratio 16:1
Fuel-oil system Common Rail от Bosch
Maximum fuel consumption of one engine, kg / h 21
Cooling system Liquid
Motor maintenance weight, kg 214

Flexible fencing


The amphibious qualities of the hovercraft are provided by the separation of the body from the screen due to the holding of an air cushion under the body by a flexible fence. The lift height depends on the speed of the blowers (engines) and the trim angle.

The hovercraft adopted a two-tier flexible fencing scheme with removable elements along the entire perimeter of the lower tier and with a flexible receiver in the upper tier. This scheme allows removable elements to remain elastic.

Those when passing through obstacles, the flexible elements deflect and pass the object under them without resisting its impact. Only the lower segment tier, which consists of many independent elements, participates in contact with the surface. Each element is attached to the receiver with four clamps. Replacement is simple and requires no special tools or skills.

Due to the constant air flow in the airspace in dash air bubble, the flexible fencing retain the ability to move the hovercraft even if all removable elements are lost. The flexible fencing material – rubberized fabric based on rubber nylon. This fabric allows you to expand and take a given shape in low temperatures.

The maximum achievable height of the air cushion is about 0.75 m. The height of the air cushion is measured from the supporting solid surface to the bottom of the hull.

Air bubble propellers and blowers

Two four-bladed propellers of variable pitch in aerodynamic fixed nozzles are provided as propellers on the hovercraft. The support unit of the variable pitch propeller and the reverse mechanism are located in the pylons of each nozzle. The propeller blades are made of fiberglass composite coated with aramid.

The angle of rotation of the propeller blades is controlled by direction indicators installed in the control panel. Two twin centrifugal blowers are provided as air cushion blowers. The air cushion blowers operate separately, each on its own side. The blowers are mounted on shafts supported on both sides by self-aligning bearings.

The blowers are made of fiberglass, carbon fiber and aramid. Separate control of the speed of the blowers (n1 and n2) and the sectioning of the air cushion zones allow creating different pressures in the left P1 and right P2 halves.

This property makes it possible to create an artificial bank, which greatly helps with maneuvers and helps to neutralize the effect of side wind gusts. In the event of a failure of the engine or the supercharger of one of the sides, the jumper between the zones is removed and the flexible fence is filled with air from the working supercharger. The hovercraft can continue to move on one supercharger.


Directional control is provided by turning the steering wheel in the helm station and rudders installed in the stream behind the propellers. Rotation of the rudders provides control torque with the center of rotation in the nose area. Provision is made for shifting propellers of variable pitch from FORWARD to REVERSE. Shifting is done both jointly and separately by pedals located at the driver’s feet. The split shift provides a control torque with the center of rotation in the stern area.

The propeller speed control is provided, which provides different thrust and creates a control torque with the center of rotation in the stern area. The possibility of hovering on an air cushion at low speeds is provided by installing the propeller blades in several intermediate positions in the range of angles from full forward to full rear.

Shifting the blade of one propeller backward is provided, corresponding to the shifting of the blade of the other propeller forward (work in disarray) Remote control of the power plant is performed by levers located on the control panel.


The hovercraft has been approved by the Russian River Register for the class “undersized category * 3”. This allows you to use it in the following options: For personal and business needs without the right to commercial exploitation. Number of seats up to 12 people + cargo.

Swimming is permitted – INLAND WATER-WAYS not higher than “P”. In winter, on ice without limits. STATE INSPECTION OF SMALL VESSELS (SISV) registration. Amateur rights. For passenger transportation MP, INLAND WATER-WAYS with the right of commercial exploitation. Number of seats up to 12 people.

Sailing permitted – INLAND WATER-WAYS not higher than “P” or MP 6 miles from the place of refuge. In winter, on ice without limits. Registration of the River Register. Amateur rights. A place of refuge is any naturally or artificially protected water area that can be used to shelter a vessel in the event of circumstances that threaten its safety. For a hovercraft, this is any land area where a vessel can go, i.e. actually coastal sailing.

Passenger – any person on board a ship, except for the captain and crew members or other persons working or having any occupation related to the activities of this ship (special personnel), as well as a child under one year old.


Hovercraft can be transported on a special trailer, in one 40-foot container + one 20-foot container, an auto-trailer with a trailer length of 13 meters.


The hovercraftis equipped with the following systems:

electric (12V, 2 batteries)

fuel (400 liters)

engine cooling

charge air cooling (turbocharging, intercooler)

gas exhaust (stainless)

ventilation of the passenger compartment and engine compartment

trimming (200 liter tanks in the bow and stern)

steering (two groups behind nozzles, 4 rudders each)

fire fighting


The hovercraft is standardly equipped with:

life jackets by the number of passengers

two xenon headlights on the handle

two water-air heaters from different engines


windscreen washer and wipers

trim indicator

two on-board diagnostic computers Multitronics (engine speed, voltage, remaining fuel in tanks, coolant temperature, errors)

indicator of the angle of attack of the propeller blades

indicator “Fire” in the engine compartment

electric amplifiers the variable-pitch propeller

dehumidification pumps

roof cargo hatch

gull wing doors 850 mm wide

radio tape recorder, cup holders, glove boxes, cigarette lighter, ashtray, etc.