Do-it-yourself hydrofoil for a boat motor: video instructions

General information

Anti-cavitation fenders for outboard motors could be found in the Indian Ocean, in Central Europe on various bodies of water, in the Baltic, on the Great Lakes, in the Indian Ocean, in general, wherever there is open water.
At first glance, this modification seems strange, but once you figure it out, everything becomes extremely simple. Many lovers of motor boats, especially inflatable ones, sometimes think about improving their vehicle. There are situations when you see a similar craft with a similar engine, but it goes on planing faster, with good control, and it moves easier through the water. That’s when the owner of the boat begins to think what’s wrong with his vehicle, and what is the difference with almost identical engine characteristics.

And it’s not the boat at all, but the special equipment – the hydrofoil. There are two types of such wings: monowing and standard hydrofoil.

Why is it necessary to use a hydrofoil for a boat motor?

This useful modification mainly affects the planing mode, so it is rational to install it only to improve this indicator. There is no point in installing it for both powerful engines and weak ones (less than 10 hp).

Planing (planing) is the movement of something, while it slides along the surface of the water due to speed and friction coefficient.

In addition to all of the above, the hydrofoil will help reduce fuel consumption, prevent cavitation during sharp turns, and the special shape will help make it easier to take off.

Two main types of hydrofoils

There are two types of hydrofoils:

Monowing – made as a single plate;
Standard – two plates.

Wings can also be divided into types according to power: 25-30, up to 50, over 50 hp.

The first type of wings is recommended for installation on medium and high power motors. This is due to the load on the engine during planing.

Types and features

Hydrofoils are usually divided into two main types:

Monowing. This device is a solid plate, which is recommended for use primarily on engines of medium and highest power, due to the design features.
Standard hydrofoil. It consists of two separate parts. They should only be installed on low power motors. Most often used on outboard boat engines.

It is worth noting that manufacturers have their own classification based on power:

the first group is intended for equipment with motors with a total power of up to 25 hp;
second group - 25-50 hp;
the third group is engines exceeding the 50 hp mark.

Classification of hydrofoils by power

You should not install a hydrofoil if the engine power is less than 6 hp, because in this case its efficiency is reduced to zero. It is also not worth installing it on engines with a power above 50 horsepower. The best option for installing a hydrofoil is an engine with a power of 12 (+-4) horsepower, because this will not significantly affect the speed, but will significantly improve the performance of the boat.

As already mentioned, hydrofoils are divided into types based on motor power:

First group – up to 25 horsepower:
Second group – 25-50 horsepower;
The third group - more than 50 horsepower;

Best models

Among the popular products are:

Hydrofoil Easterner

From a Taiwanese manufacturer.

This is a budget option, its cost is 1220 rubles. The device is intended for boats with an engine from 8 to 50 l/s.

The material used is black plastic. Device dimensions 194×174 mm. The kit includes special fastening elements.

Hydrofoil from the Sport Marine brand (USA)

The cost of the product varies between 4000-5000 rubles. The device is specially designed for engines with power up to 300 l/s.

To install it, you do not need to drill the anti-cavitation plate.

Hydrofoil SE sport SES400

Price 6220 rubles. The device is installed on motors with a power of over 40 l/s. Dimensions 40.6x43.2 cm.

The kit contains everything you need to mount such a device, and there is also a special adapter for installing it without drilling holes.

Advantages and disadvantages of use

After installing such a wing on the engine, the owner will receive:

Planing time will be reduced by 15%;
More stable running of the inflatable boat;
With a sharp increase in engine speed, the nose does not lift up so much.
The stability of the boat will improve due to the increase in the area of the anti-cavitation plate. This will also improve control of the vessel's behavior;
Due to the holes that are located in front of the wings, air enters there and creates an “air cushion” effect, which reduces the contact of the boat with water;
It creates the opportunity not to lose speed during sharp turns;
Comfort when operating the watercraft.

There are also disadvantages when using a hydrofoil:

The maximum speed will drop slightly;
You will need to cut it out if you get caught in the net;
Propeller clogging can also occur, especially in shallow water. The wing partially blocks access to it, which interferes with cleaning;

Installation process

As mentioned earlier, the installation process itself is not very complicated, however, a person is required to have at least a superficial knowledge of the structure of a boat motor.

Many experienced boaters use special kits for this, for example, SportClip. An alternative is to drill holes for the bolts. This method can damage the plate, so it is better to stick to the method that uses fastening.

The process itself:

Before starting work, the surface must be degreased, wiped off dust, removed excess grease and wait until it dries completely.
After this, you can begin gluing special gaskets. In order for everything to work out as it should, you should do this work indoors where the air temperature is above 18 degrees or outside on a warm day. This promotes a tighter fit of the gaskets and improves the quality of gluing.
The next step is installing the top plate.
Then the lower part of the structure is mounted and everything is fastened with four bolts. The bolts must be tightened sequentially in a clockwise direction. When using the kit, the rubber washers that come with it will be used instead of bolts.

Don't forget that:

the hydrofoil has a noticeable effect only for engines from 6 to 50 hp;
the angle of attack is not important for low-power engines;
the hydrofoil slightly reduces fuel consumption, and, in addition, increases the speed at which the boat enters gliding mode;
It is preferable to choose a mounting method using SportClip type kits.

Why do you need a hydrofoil for a boat motor? Most owners of inflatable motor boats have at least once thought about upgrading (improving) their boat and motor. This often happens when you see a similar boat on a body of water with a motor of comparable power, but this boat moves through the water easier and gets on plan much faster. Doesn't turn up the nose with a sharp increase in thrust. And the gliss itself is subject to it at a higher load. Thoughts involuntarily arise that you are doing something wrong or that your outboard motor or the boat itself is configured incorrectly somewhere. Do not worry. Everything is fine with your motor and boat. It’s all about such an additional device, or better called equipment for a boat motor, like a hydrofoil. Hydrofoils for outboard motors come in two types: monofoil (a large single plate) and standard (consists of two separate parts, two wings). See photo.

Advantages of hydrofoils for outboard motors: Faster access to planing. The exit time is reduced by about 15-20%. Increasing the area of the anti-cavitation plate itself improves the directional stability of the motor boat. The bow of the boat does not lift up so much with a sharp increase in engine speed.

Disadvantages of hydrofoils for outboard motors: A drop in maximum speed by about 5%. When sailing in shallow water, if grass or something like that gets wrapped around the propeller, then removing all this from the propeller will take you longer than without a hydrofoil. The hydrofoil blocks access to the propeller. According to our tests and observations, hydrofoils should not be installed on engines with power below 8 hp. The effect will be practically zero. Well, for fairly powerful engines, a hydrofoil will not give any noticeable result. And without a wing, a 50 hp outboard motor. will get almost any boat on plan in a very short time. If you and your boat don’t have any problems getting on planing and the boat doesn’t get into a cobra position when starting, then a hydrofoil will be just a fashionable accessory for you, which will also “eat up” your maximum speed. But for weak engines, with which the boat can barely glide, a hydrofoil can be a useful acquisition. If you still think that a hydrofoil for a boat motor will not help you, try installing a hydrofoil for an inflatable boat. It can be installed on any types of inflatable boats.

Testing hydrofoils for outboard motors:

Choosing the right hydrofoils

The correct choice of anti-cavitation wings directly depends on the power of your motor. If your engine produces up to 50 horsepower, then it is better to use a monowing. This is connected, of course, with the shape of the wing. As for companies, the choice here remains only with the owner of the boat. One of the popular magazines published in Germany conducted a small test that will help you understand what an anti-cavitation wing is and choose the best brand, in your opinion.

The test was carried out on a 4.5 meter long RIB. Its engine power is 40 hp. Four types of anti-cavitation wings from different companies took part in the test. The total weight on the vessel was as follows: 2 people and 140 kg for the entire boat. Testers moved additional weight around the motorboat to create an overload situation.

The main criteria by which the wings were evaluated were: acceleration to 30 km/h, fuel consumption and boat speed. During the test, the following wing models were tested: Attwood, AttwoodKlein, Doelfin, Lalizas. Let's briefly talk about the results:

AttwoodGross - this model did not fit the motor. The ship quickly reached glide, but the maximum speed decreased by almost 6 km/h!
AttwoodKlein is a great solution for a small boat. Due to the anti-cavitation wing, the engine produced more revolutions, which made it possible to reduce acceleration time. The thirsty engine began to consume less fuel at 3300 rpm. The overall speed decreased slightly, however, in return we received fast acceleration and access to glide.
Doelfin – the best results were shown by the wings from the manufacturer Davis. They reduced the speed of the boat the least and brought it to glide faster. However, fuel consumption has been slightly increased.
Lalizas are small wings similar in characteristics to AttwoodKlein. Suitable for small boats with outboard motors.

A hydraulic wing should not be installed for engines whose total power does not exceed 6 hp. All the efficiency and benefits of a hydrofoil on a very weak engine are reduced to zero. You will not get any quick gliding or quick acceleration from a standstill.

Hydrofoils

(2)

Let's discuss the advantages, main mistakes and installation of hydrofoils on outboard hybrids and other outboard motors.

First of all, it must be said that hydrofoils are most effective at speeds up to 9 m/s (32 km/h), since at higher speeds they create too much resistance and provoke nose-diving, negating their advantages.

How does a hydrofoil help you achieve planing? Let's consider the theoretical aspects of creating lift. Any flat platinum or profiled body (with different efficiency), when moving at an angle to the flow of liquid or gas, creates a zone of increased pressure on the lower surface and a zone of resolution on the upper part. Moreover, the resolution zone creates 1.5-3 times (depending on the profile) more lift than the high-pressure zone (this is why hydrofoils are so small). The lift force increases with the square of the speed. For example, if the lifting force at a speed of 2 m/s is 4 kg, then at a speed of 4 m/s it is 16 kg. In addition, the lift force directly depends on the angle of attack to the oncoming flow. It is these factors that influence the reduction in the overall resistance of the hull at the moment of planing. So, let's list all the pros and cons of using a properly designed hydrofoil on a boat hybrid and other outboard motors.

Pros:

Removes the "cobra".
We speed up the planing.
Stops air pick-ups from the surface when turning.
Reduces slippage on punt turns.
Allows you to raise the motor by 1-5 cm.
Cardinally reduces propeller aeration on flat-bottomed boats (deadrise up to 8 degrees) by sucking in air that has broken through the bottom of the boat from the surface to the upper part of the wing, leaving only a clean flow of liquid for the propeller.
Improves seaworthiness by reducing longitudinal sway on a wave (tested on a 2.45 m plywood punt; allows you to ride a wave of up to 50 cm in 3/4 throttle at a speed of 20-22 km/h; the traditional strong impact on the second wave is practically absent).
Optimizes the operation of the propeller, increasing its efficiency (when using the correct wing, the propeller has the passport efficiency; without it, 10-15% of the thrust is usually lost).
Allows you to plane an additional 5-50 kg of cargo (depending on the kit).

Minuses:

Reduces the maximum speed of the kit by 1-2 km/h.

There are a number of other features of hydrofoils that affect their efficiency: the shape of the wing, the span-to-width ratio (it is these parameters that greatly influence the inductive drag), the installation location of the wing (affects the optimization of the operation of the propeller), adjustment possibilities (elevators, positive or negative transverse V).

For engines up to 10 hp. the installation of hydrofoils with a thickness of more than 2.5 mm is not recommended, since their drag becomes too large and does not allow for gains when entering planing.

The most successful fastening of hydraulic wings is 4 5 mm screws with self-locking nuts to the automatic transmission. This fastening scheme creates a minimum of resistance.

We offer hydrofoils designed for Veterok's feet. Also suitable for most engines from 3.5 to 12 hp, including Honda 5, Veterok 8, Veterok 12, Moscow 10.5 and Moscow 12. Detailed information on the link below:

Hydrofoil for outboard motor 3.5-15 hp. / boat hybrid Veterok

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Step-by-step process of installing a hydrofoil on a boat motor

Installing a fender on an inflatable boat motor will not be difficult if you have at least a little knowledge about the motor and its structure. You need to know what an anti-cavitation plate is, because the wing is installed on it. For installation, many experienced fishermen and racers use kits like the SportClip. An alternative is to simply make holes for the bolts, but in this case, careless action may damage the plate. Therefore, we will use fasteners.

You will have to think about where it would be better to make holes for the bolts in the anti-cavitation plate so that the hydrofoils are positioned symmetrically.

All work is carried out outdoors in good, warm weather or in a well-heated room, at a temperature of ~18 degrees. First you need to remove grease from the surface of the stove, wipe off dust and remove unnecessary grease. After it is completely dry, we glue special gaskets. Warm air temperatures will improve the quality of adhesion and help the gasket adhere more tightly to the surface.

Next, the top plate is installed, then the bottom part of the entire set, which is bolted on four sides. The bolts are tightened clockwise, one after another. The kit contains washers instead of bolts; they are also used as fastening.

Hydraulic wing installation

It has already been mentioned that the installation process of this modern boat unit is not overly complicated and costly in terms of time and effort. It is believed that even a novice powerboat driver can install a hydrofoil. Although this still requires him to have certain experience and knowledge in the field of outboard motor design. To do this, it is best to study the diagram of the outboard motor yourself or with the help of a specialist. Or do this by disassembling this unit in order to understand firsthand what is happening inside it.

DIY hydrofoil

Many fishermen and racers prefer to make this device themselves in order to save extra money. Fortunately, making it yourself is quite simple if you know how to work with your hands. There are a great many ways to make such a wing, let’s look at one of them:

The material used is the canvas of a shovel (possibly plastic). It has good strength, has a suitable shape and is easy to cut with a grinder.

First you need to disconnect the blade from the cutting and remove the continuing groove. It will serve as an opening for the screw part of the motor. Next you need to measure the motor leg; The results obtained must be accurate for a tighter fit of the wing. Then you need to make holes to fasten the sheet to the anti-cavitation plate.

The attachment on the grinder should be for carving. We round off the sharp corners, we don't need them. On the side where the blade will be attached to the screw part, you need to cut the perpendicular edges at an angle of 20-30 degrees, and leave the other side straight, removing the corners. The outline of the structure should be streamlined.

If the shovel initially has concave edges , straighten them with a hammer; in the case of plastic, it is better to remove them. Many people prefer to cut out the anti-cavitation wing from aluminum, this method can be easily found on the Internet.

Tips and tricks for using hydrofoils for outboard motors

If your boat quickly reaches glide, then wings, in general, are not needed. However, if there is good trim to the stern or excessive stern centering of the craft or lack of engine horsepower, hydrofoils can solve the problem of entering planing mode. They are also designed to improve the stability of the boat, especially when towing.

The maximum speed will decrease slightly (by how much depends on the design features of the selected wing model). There are many different models of monoplane fenders on the market. The essence of their use does not change, but due to the higher wetted surface area, their shape and less good elongation, their fuel consumption may increase when used.

If you decide to make a hydrofoil with your own hands, a regular shovel will work well as a material. You should try to cut out the most symmetrical and streamlined shape, and round and clean the edges. In order to secure it to the anti-cavitation plate, it is enough to drill holes for the bolts.

Whether to install hydrofoils or not is up to you.