Summary
Buying guide for electric flaps for boats
Flaps are stability and performance control devices for boats. Installed at the stern of the boat, near the engines, they consist of two movable fins that allow to modify the angle of the water pressure under the hull. The flaps are important elements to optimize navigation in rough seas, reduce fuel consumption, increase speed, stability and maneuverability of the boat.
In this article, we will deepen the functioning, the advantages of the flaps for boats. You will know the different types of flaps, the essential accessories but above all you will know how to choose flaps adapted to your boat and to your navigation.
Buying guide for electric flaps for boats
Flaps are stability and performance control devices for boats. Installed at the stern of the boat, near the engines, they consist of two movable fins that allow to modify the angle of the water pressure under the hull. The flaps are important elements to optimize navigation in rough seas, reduce fuel consumption, increase speed, stability and maneuverability of the boat.
In this article, we will deepen the functioning, the advantages of the flaps for boats. You will know the different types of flaps, the essential accessories but above all you will know how to choose flaps adapted to your boat and to your navigation.
What are boat flaps?
Electric or hydraulic?
First of all, it is necessary to differentiate between electric flaps, which we will discuss in this guide, and hydraulic flaps.
The difference comes from the cylinder which is either electric in 12v or 24v connected to the electrical system of your boat, or hydraulic, with an additional hydraulic pump generally located in the back of the boat
Nowadays, electric flaps are as reliable and solid as hydraulic flaps and even more so since there is no risk of leakage without a hydraulic system. They can easily be used on motorboats up to 20m (depending on model)
Two big brands of electric Flaps are on the market, the Bennett brand and the Lenco brand, both brands are as reliable as each other and both offer electric or hydraulic cylinders. It will be to the taste of each one to make its choice.
What are boat flaps for?
Electric flaps are an almost indispensable piece of equipment on a boat. Lenco even states: "These devices provide such convincing advantages that their users are surprised that they are not systematically installed as standard on all models.
Indeed, the flaps provide only advantages to navigation, making it smoother, more comfortable. The electric flaps allow your boat or motorboat to consume less, to correct the trim, to be faster while increasing the safety and thus avoid that the nose of the vessel rises at the time of a catch of speed. The piloting of the boats is facilitated, the boat goes straight, the speed and the performances are increased.
- Increased visibility increases safety - It is important to be able to keep the bow down at slow speeds, especially in congested areas and in bad weather. With the flaps, the boat glides more easily at slow speeds, allowing you to navigate in safer conditions.
- Fuel Economy and Increased Propulsion Efficiency - Allowing the boat to right itself more quickly means the engine also reaches its optimum performance more quickly. By taking the load off the engine, Bennett flaps significantly reduce fuel consumption and extend engine life.
- Optimize performance and ride comfort - Bennett flaps help correct the boat's trim, raising the stern according to speed, load distribution and fuel level changes.
The flaps, also called plate stabilizers or plate correctors, are usually sold in kit, you will find them online under the name of " Lenco flaps kit " or " bennett flaps kit " depending on the brand. A flaps kit contains 2 electric cylinders of 12v or 24v (depending on the model), 2 stainless steel shovels (or stabilizer plate), mounting elements (support, cable, screws) and often 2 extensions that will allow you to connect the 2 cylinders to the switch (control panel).
Operation of the flaps for boats
HOW DOES THE FLAPS WORK?
The electric cylinders are connected to a switch (sold separately), a switch is a waterproof control keyboard composed of 2 buttons allowing to raise or lower the flaps separately, a button for the left flap and a button for the right one.
They respond instantly to the slightest request from the pilot. Some switches are equipped with LEDs indicating the position of the flaps in real time .
Each shovel goes up or down thanks to the cylinder that unfolds. The pilot has the possibility of correcting the attitude, but also the pitch by raising only one plate for example.
The up flaps raise the front of the boat while the down flaps lower it. The purpose of the flaps is to keep the boat as flat as possible on the water, avoiding the lateral jolts that can be caused by a strong swell, for example, or an imbalance during acceleration, when the boat rises and obstructs the field of vision.
The flaps are mounted in the lower part of the trans om. They move into position as soon as the control is activated. The flow of water over the scoops creates a vertical thrust that lifts the stern and causes the bow to "drop". Properly sized, the flap system improves the boat's performance, regardless of the size of the loads on board, the weather conditions or the sea state.
The flaps work the opposite way you might imagine. The port flaps raise the port stern, which lowers the starboard bow. Conversely, the starboard flaps lift the starboard stern, lowering the port bow.
The control box is wired in such a way that all you have to do is think about the direction you want to steer the bow. Don't worry about how the flaps work and you'll quickly become comfortable with the controls.
The diagram below summarizes the operation and possibilities of the flaps:
How to use your flaps ?
- Finding the right attitude
To fully understand your boat's behavior, perform this test at full speed in calm seas, when the boat is lightly loaded.
Raise and lower your flaps, observe the position of the bow in relation to the horizon and the movement of your boat. Then try it in different sailing conditions. The goal is to get the boat as flat as possible on the water so that it goes straight.
- Learn to "feel" the effect of the flaps
During the learning period, use the controls in short bursts. Since there is a short delay before the boat reacts, allow some time between each pulse. The reaction time is related to the speed, size and type of boat. Do not lower the bow too much or the boat will sink into the waves. To raise the bow, use the "BOW UP" command.
- Correcting the heel
The flaps can be operated separately to allow heel correction. All control panels offer intuitive controls. Don't think about the flap action, but concentrate on the bow. If the bow is high on the port side, press the port "BOW DOWN" control. If the bow is high on the starboard side, press the starboard "BOW DOWN" control. Use only small pulses to allow the boat to respond and avoid lowering the bow too much.
- Combine the action of the flaps and the engine trim
- Use the flaps to flatten the boat.
- Use engine trim to keep the propeller parallel to the water line.
- If necessary, fine-tune the flaps.
Flap stabilizers allow you to take advantage of the engine's optimal performance as they straighten the hull while the trim aligns the propeller while reducing fuel consumption. Flaps increase the performance of motorized hulls and are versatile. They can be installed on small boats as well as speedboats and yachts.
Special sailing conditions:
- Sailing in rough seas
In heavy seas, lower the bow "BOW DOWN" with the two flaps to better split the waves and gain in comfort.
- Sailing on a following sea
In following seas, or when entering a channel, raise the flaps fully (BOW UP) for maximum rudder control. If the flaps are down, the bow may sink.
- Crosswind
To raise the windward side, use the "BOW UP" command on the same side. If that doesn't work, use the "BOW DOWN" control on the leeward side. Raising the windward tack will reduce the amount of spray you catch. Proceed gradually.
- Shallow water / Sudden acceleration
To raise the stern and raise the bow, fully lower both flaps with the BOW DOWN control. As you increase the throttle and the boat gains speed, raise the flaps with the BOW UP control.
- If the boat "porpoises" (the bow dives and bounces)
This behavior is more specific to fast boats. As the boat gains speed, the bow rises out of the water until the lift is overcome by gravity and the bow drops back down. Press the "BOW DOWN" control in short bursts. As the flaps are lowered, the "porpoising" will decrease and the speed will stabilize or decrease. Lowering the flaps slightly should be sufficient.
TYPES OF ELECTRIC FLAPS
Different types of flaps for different boats
There are many sizes of flaps for different sizes of boats, but also flaps with 2 cylinders for very large boats, Edge Mount flaps recommended when the height available on the transom is low and you will also find kits in 12v and 24v.
Single and double actuator flaps refer to the number of actuators needed to operate the flaps. Single-acting flaps have one actuator that pushes and pulls the flap fin to adjust it, while double-acting flaps have two actuators that work together to adjust the fin.
In terms of electrical voltage, flaps are available in 12V and 24V to meet the needs of different boat electrical systems. 12V flaps are typically used on small recreational boats, while 24V flaps are more common on larger boats and commercial vessels.
The choice between single or double flaps will depend on the size and weight of the boat, as well as the force required to operate the flaps.
Single cylinder flaps
Lenco standard flaps
The standard Lenco flaps sold in kit with 2 electric cylinders, 2 stainless steel shovels, 2 extensions of 6m are powered in 12V(optional 24V cylinders can be installed).
They require a minimum transom height of 360mm and are available in several sizes for boats ranging from 5m to 15m.
Flaps Bolt Bennett
The Bennet electric flaps model Bolt considered as the equivalent of the Lenco Standard Flaps and are also equipped with a 12V electric cylinder.
Sold in kit with 2 shovels, 2 jacks and 2 extensions of 6m also they are adapted to the boats until 9m.
Flaps Lenco Edge Mount
Lenco Edge Mount flaps are also single 12v jacks and are ideal for boats that do not have enough transom height to mount standard flaps. Also sold as a kit with 2 electric cylinders, 2 shovels and 2 6m extensions ideal for boats from 5m to 20m. Available in several sizes.
There is no equivalent for the Bennett Bolt flaps, but you can buy in option at Bennett shorter cylinders of 300mm instead of 350mm
The best boat flaps
Standard 12v Flaps Kit
Standard 12v flaps kit for powerboats from 5 to 20 meters depending on the model. The flaps will be used to lower or raise the nose of the motorboat in order to adjust the trim and thus combine power and comfort while sailing. They will also allow toavoid the heeling that can cause a strong crosswind and thus optimize the glide on the water. The kit is composed of 2 standard jacks, 2 stainless steel shovels, 2 6m extensions and mounting accessories.
⚠️ For these Standard single cylinder flaps, you will need a single cylinder flap switch: LC245, LC249 or LC246 (sold separately)
Bolt 12v Flaps Kit
The Bennett BOLT Flaps kit is available in several sizes for boats up to 9m (See the Flaps guide here)
Bennett 12v electric flaps are built to last longer than any other electric flap system on the market. Waterproof, reliable, durable and easy to install, Bennett flap kits will correct the trim of your boat to ensure maximum power and speed even in rough seas.
Each kit consists of 2 flaps (jacks + stainless steel shovels) and 2 extensions of 6m
⚠️ For these Bolt Bennett flaps, you will need a switch for Bennet flaps: BE704 or BE713 (sold separately)
Edge Mount 12v Flaps Kit
Lenco EDGE MOUNT electric flaps are recommended when the available height on the transom is low, or if the transom is equipped with an exhaust outlet, a bathing ladder or any other equipment that prevents the installation of the standard flap kit.
Composed of 2 stainless steel shutters and 2 jacks, 2 extensions 6m and mounting accessories.
⚠️ For these Edge Mount single cylinder flaps, you will need a single cylinder flap switch: LC245, LC249 or LC246 (sold separately)
SUPER STRONG FLAPS
Lenco Super Strong Double Cylinder Flaps
The kit flaps double jacks or Super Strong double jacks are composed of 2 wide shovels with 2 electric jacks 24v on each so 4 electric jacks a little shorter than the standard and reinforced jacks. No maintenance required, they are 100% waterproof like all Lenco and Bennett flaps.
Delivered without extension, the Super Strong double cylinder flaps are intended for large boats from 15m to 20m.
NB: For this model the cylinders are only in 24v.
Single cylinder flaps Super Strong Lenco
Little brother of the super strong double cylinder flaps kit, this one is composed of 2 cylinders reinforced in 12v or 24v (1 cylinder per shovel) and 2 stainless steel shovels.
It is a solid and powerful single cylinder for vessels from 7m to 18m about.
Super strong flaps are designed to withstand higher speeds than traditional flaps and provide greater boat handling on the open ocean. They are also more resistant to wear and damage from salt water and harsh weather conditions.
The best reinforced boat flaps
Super Strong Single Cylinder Flap Kit
12v or 24v
Some boats require an even more powerful installation, so Lenco has created the SUPER STRONG line of reinforced flaps, equipped with a 4.8 mm thick stainless steel scoop and extremely robust mounting hardware to withstand the harshest of sailing conditions.
Nb: you will need 2 cylinder extensions (sold separately) per Flaps Super Strong single cylinder kit to connect to your switch.
⚠️ For these single cylinder Super Strong, you will need a single cylinder flap switch: LC245, LC249 or LC246 (sold separately)
Bolt 12v Flaps Kit
The SUPER STRONG reinforced flaps, equipped with 4.8 mm thick stainless steel shovels, are designed to withstand the toughest sailing conditions. This model of flaps has 2 electric cylinders 24V by shovel for a force of 2 times 340kg.
Nb: you will need 4 cylinder extensions (sold separately) per Flaps Super Strong double cylinder kit to connect to your switch.
⚠️ For these Super Strong Dual Cylinder Flaps, you will need a Dual Cylinder Flap Switch: LC240 or LC241 (sold separately).
HOW TO CHOOSE FLAPS FOR YOUR BOAT
Choose the right size of flaps
Many different sizes, shapes and cylinders exist for boat flaps, here are some things to consider when choosing electric flaps:
- Boat size and weight: Electric flaps are designed to work with boats of different sizes and weights. It is therefore important to choose electric flaps that are appropriate for the size and weight of your boat.
- Hull shape: The shape of your boat's hull can affect the performance of the electric flaps. Boats with a deep V hull may benefit from larger electric flaps for better lateral stability, while boats with flat hulls may require smaller flaps for righting effect.
- Type of boating: If you plan to sail primarily in calm waters, you may not need very large flaps. But if you're sailing in rougher waters, you may need larger flaps to stabilize your boat.
- Engine power: Engine power can also affect flap selection. If you have a powerful engine, you'll need larger flaps to help keep your boat stable at high speeds.
- The characteristics of the flaps: Finally, it is important to take into account the characteristics of the flaps themselves, such as their lifting capacity, the number of cylinders, the size of the cylinders according to the size of your transom, etc.
You can find the general guidelines for choosing flaps on the right, and you can also get an idea of the size required for your boat by consulting our product sheets
WHO CAN MOUNT FLAPS ON THEIR BOAT?
The use of flaps is not reserved for professionals and any boat can be fitted with flaps if the manufacturer's recommendations in terms of boat size are respected.
Moreover, the installation is very simple and can be done at home, the bennett and lenco flaps are installed in almost the same way. The installation is so simple that manufacturers and users are surprised that their installation is not systematically applied as standard on motorboats.
NB: If you have Lenco flaps, you will need a Lenco switch and similarly Bennett flaps will require a Bennett control panel.
VIDEO INSTALLATION FLAPS LENCO
VIDEO INSTALLATION FLAPS BENNETT
ACCESSORIES FOR FLAPS
WHAT ACCESSORIES ARE NEEDED TO USE MY FLAPS?
The switches for flaps :
To use your Flapsyou will need aa switch of the same brand, Lenco for example proposes switches of different kinds, the ISK models models composed of an integrated management box which requires about 11cm of depth for embedding and a V2 model with the with the external management box. A switch is an essential equipment for the use of the flaps.
The control panels are equipped with 2 buttons that respond to the slightest request from the pilot, for the right and left flaps, a simple pressure allows to raise or lower the shovel. The connection between your cylinders and your control panel is made via the extensions quick connect extensions (supplied in some kits) and available in other lengths as options.
The switches can be equipped with LEDs that continuously indicate the position of your flaps. If you have a 2nd cockpit on your powerboat like a Fly bridge cabin for example, you can use a second flybridge switch in addition to your main switch.second flybridge station switch.
cf: below is a diagram of a V2 second station switch with a V2 main control panel
spare part, cylinder, extension
When installing a flap kit you will have to take into account the voltage your boat delivers (12v or 24v) and the length of your boat (a small boat will not have the same flaps as a yacht).
Indeed most of the flap kits are in 12v, but you can buy replacement cylinders in 24v.
Also, the standard and Edge Mount flap kits come with 6m extensions, but not the super strong ones, so we offer additional extensions up to 15m .
Some accessories for boat flaps
Replacement cylinder for Lenco Flaps
The lenco flap jacks are available in 4 models:
For your Standard Flaps or Edge Mount Flaps :
- LC200 Cylinder : Standard model in 12v
- LC201 Cylinder : Standard model in 24v
=> L = 30.8 cm, Hole = 0.79cm
For your Super Strong single cylinder or Super Strong double cylinder flaps:
- LC202 Cylinder : Reinforced model for SuperStrong single cylinder flaps in 12v
- LC203 Cylinder : Reinforced model for SuperStrong single and double cylinder flaps in 24v
=> L = 28.89cm, Hole = 0.95cm
Extension for Lenco flap cylinders
Cylinder extensions with quick connectors allow you to connect your Flaps to your ISK or V2 waterproof switch. These extensions are available in 6m, 10m or 15m
⚠️ Generally, 1 extension per cylinder is required, so 2 extensions per single cylinder flap kit / 4 extensions for double cylinder SuperStrong flap kit.
NB : Lenco Standard Flaps and Lenco Edge Mount Flaps kits are delivered with a 6m extension.
