How to lift a transom on a PVC boat yourself

Many inflatable boat owners are faced with the issue of upgrading the stern, especially if the standard height of the engine does not allow to realize its full potential. Raising the transom on a PVC boat is a popular procedure that solves the problems with the screw air sucking and allows you to install a more powerful engine than the manufacturer claimed for the basic configuration. However, this intervention in the design of the vessel requires accurate calculations and understanding of hydrodynamics, so as not to turn the boat into an unguided projectile.

The challenge is that the inflatable balloon has a certain elasticity, and the rigid insert on which the motor is attached must work in tandem with the soft body. The wrong lifting of the transom can cause the center of gravity to shift, roll at the stern, or even break the seams at the power kit attachment points. In this article, we will take a look at all the steps of the process, from the choice of method to the test swims, so you can do this safely and efficiently.

Before you start to take up tools, you need to assess the current state of your boat and understand what kind of modernization method will suit you. There are several proven ways to change the geometry of the feed, each of which has its advantages and limitations in applicability to different models. PVC boatsThe choice depends on the type of bottom, the design of the power set and the desired lift height.

Analysis of the need for transance lifting

The first step is always to diagnose the current situation, because not every boat needs to be reworked. outboardThis phenomenon, known as stern different, significantly reduces speed and controllability, increasing fuel consumption. If the boat's nose is raised too high when it is glides, and the propeller begins to grab air, creating cavitation, then changing the angle or height of the transom is necessary.

On the other hand, interference can impair driving performance, and if the boat is originally designed to take into account a particular center of gravity, artificially raising the mounting point of the engine can lead to yaw and loss of course stability. It is also important to consider that when lifting the transom, the lever arm acting on the aft part of the cylinder increases. power-set and the place of gluing, which is especially critical for boats with low pressure inflatable floor (LDP), where the rigidity of the structure is lower than that of solder models.

There is a common misconception that the higher the engine, the better. In fact, optimal height is a trade-off between minimizing water resistance and ensuring that the engine cooling pumps keep water flowing. Too high a lift will cause the engine to overheat and lose traction when the screw is exposed. So, before starting work, it is recommended to conduct experiments with engine hinges, using temporary gaskets or adjusting the angle of inclination with standard means to find the "golden mean".

• 🚤 Increased plane speed by reducing water resistance.
• ⚖️ Compensation of weight of a heavy motor or battery displaced on the stern.
• 🌊 Elimination of water flooding into the cockpit during the course on the wave.
• 🔧 Possibility of installing a motor with a longer leg on a boat with a short transence.

If your boat has a soft transom (inflatable imitation), then its lifting is possible only by replacing it with a hard insert or installing an additional adapter. The hard transmuter, which is an extension of plywood floorboard, is easier to upgrade, but requires accuracy when working with moisture-resistant plywood and fiberglass. Remember that any changes can affect the manufacturer's warranty, so weigh the pros and cons.

Selection of modernization method and tools

There are two main ways to do this: make an elongated transom plate or install an adapter between the standard transom and the motor. The first option is more radical, requiring replacement or major modification of the stern part of the boat, effectively changing its geometry. The second option is more gentle and reversible, allowing everything to return to its original state at any time. The choice of method depends on your carpentry skills and willingness to make changes to the design of the boat.

To make an elongated transom, you need a high-quality PVF plywood that is not afraid of moisture and has high strength. The thickness of the material must correspond to the standard or be slightly higher to compensate for increased loads. If you choose the path of installing the prostrate, you can use an aluminum profile or also plywood lined with fiberglass. It is important that the material of the prostrate is light but rigid, so as not to create excess inertial mass on the stern.

⚠️ Attention: The use of conventional construction plywood or chipboard is strictly prohibited! After absorbing water, such material will swell, lose strength and lead to the destruction of the transom directly on the water, which can cause the boat to sink.

As for the tools, you'll need a wood-saw jigsaw, a grinder or sandpaper of different grains, epoxy resin with fabric (glass fabric) to protect the edges, and stainless steel fasteners. Don't forget about PVC sealant for boats if you plan to paste new elements, and PVC glue if you need to refine the cylinders. You also need measuring tools: roulette, coal miner and level to keep symmetry.

Special attention should be paid to the choice of fasteners. Because the transom experiences vibrational loads, ordinary nuts can spontaneously unscrew. Be sure to use growers (spring washers) or threading fluid. Bolts should be with a wide hat so as not to damage the material of the boat, and their length should be chosen so as to exclude sharp edges inside the cockpit, which can injure passengers or damage property.

Technology of manufacturing of elongated transom

If you decide to make a new, elongated transom, the process begins with dismantling the old one. Carefully remove the transmutation board, trying not to damage the shackles and the places of adhesion to the cylinder. Using the old transmuter as a template, mark the outlines on a new sheet of plywood, adding the necessary height. Usually raise the transmuter by 30-50 mm, but in some cases, especially for boats under high-power engines, this figure can reach 70-80 mm.

You need to be precise when you saw the workpiece, you need to have the edges perfectly flat, no chips or burrs, after you saw it, you need to treat the ends and the planes of the new board, you need to go through the big sandpaper first, then you need to go through the small sandpaper to get smooth. The next step is lamination. You need to apply a few layers of epoxy with glass fiberglass, and not only will protect the plywood from water, but you will also have extra strength, which is critical for the plywood. powerplate.

Parameter	The regular transnet	Upgraded transom	Units of measurement
Height.	380-420	450-500	mm
Plywood thickness	9-12	12-15	mm
Materials of coating	Paint/Luck	Fiberglass	-
Weight (approximate)	2.5-3.5	4.0-5.0	kilogram

The important thing is to keep the angle of the topping up. If the standard transom is tilted backwards (which is typical for most boats for better plane), then the new transmuter must completely repeat this angle. The change in angle can cause the boat to peck with its nose or, conversely, burrow with its stern. Use a conveyor or make a pattern of cardboard in front of a sharp plywood to accurately copy the angle.

Secrets of working with epoxy resin

When working with the manufacturer of epoxy, it is important to observe the temperature regime. If the room is colder than +15 ° C, the resin may not polymerize or freeze for too long, remaining sticky. Also, do not mix the components "by eye" - use kitchen scales or syringes to accurately comply with the proportions specified by the manufacturer. Air bubbles from the layers can be removed with a hairdryer or rolling roller.

Once the resin has been dryed and the finishing grinding has been done, you can start installing it. If the boat design permits, the new transom can be pasted into the balloon pockets using a special glue for PVC. However, the most common option is to fit it into regular pockets with additional straps or bolts through the basement beam. Make sure that the new transmolant fits tightly to the cylinder throughout the area, leaving no gaps where water could accumulate.

Installation of the insert (adapter) on the motor

A simpler and less invasive way is to make a sling that is placed between the trunk of the boat and the step of the motor, which is a rigid plate with holes for an outboard motor anchorage and under the transom bolts, which is good because it does not require disassembling the boat and can be easily dismantled when selling the boat or having to return everything to factory condition.

For the manufacture of a stretcher, D16T aluminum or thick plywood, qualitatively protected from moisture, is best suited. Aluminum is preferable, since it is lighter and does not fear corrosion (with proper anodizing or painting). The thickness of the stretcher is calculated individually, based on the desired lift. Standard values are 25, 38 or 50 mm. It is important to understand that with the stretcher the studs of the motor mounting are extended, so the regular bolts may not be enough.

When installing the wire, you need to lengthen the fasteners. Use stainless steel bolts of the same grade (usually 8.8 or higher). Between the wire and the transcrete, and between the wire and the motor, it is recommended to install rubber gaskets or use vibration insulating washers, this will reduce the vibration transfer from the working engine to the boat hull, which will make the trip more comfortable and prolong the life of the glued seams.

• 🛠️ Easy to manufacture: you do not need to disassemble the boat.
• 💰 Cost-effectiveness: fewer materials and tools are required.
• 🔄 Reversibility: You can quickly remove and return the standard configuration.
• 📏 Accuracy: It is easier to find the desired height in increments of 5-10 mm.

However, this method has its disadvantages: the insert increases the total weight on the transom, albeit slightly, and it also pushes the point of application of force further from the cylinder, increasing the lever of pressure on the aft part. Therefore, it is not recommended to use the inserts thicker than 50 mm on soft transom boats or small boats (up to 3 meters), as this can lead to deformation of the stern.

Critical aspects of safety and load

When you lift a transom, you change the load distribution, and you can't forget that for a second, the rule is, the higher the motor is, the greater the lever that acts to remove the transm from the cylinder. When you go into a sharp plane or hit a wave, the force that wants to tear the transmolor increases many times, so strengthening the attachment sites is not just a recommendation, but a necessity.

If you own an inflatable floor boat (BBB), be especially careful. These boats are less rigid in the longitudinal direction. The rise of the transom can cause the full-gas stern to bend downwards, forming a kind of "pocket" that will slow the boat down. In the worst case, this leads to the tearing of the power stringer or the destruction of partitions inside the cylinder. For such boats, the lift of the transom should be minimal or accompanied by the installation of an additional rigid frame.

⚠️ Warning: Never exceed the maximum power allowed on the boat's passport, even if you lift the transom. Raising the transom does not increase the safety margin of the hull, it only changes the fluid dynamics. Excessing power threatens to rupture the seams and an emergency situation on the water.

Also worth considering is the effect of transom lifting on handling. Reversed center of gravity can make the boat more sensitive to passenger movements. Sharp movements on the stern will cause more noticeable swelling. In addition, high transmolets can make the gas handle uncomfortablely high if the motor has a short tiller handle. In such cases, you have to buy a bumper extension, which adds another element to the chain of potential breakdowns.

Remember the cooling system. As mentioned earlier, pump intakes must be underwater. When the transom is high at low speeds or rolling, the motor can capture air. Keep an eye on the engine temperature, especially during the first hours of operation after upgrading. Installing a temperature indicator ("temperature") on the motor will be an excellent solution for controlling the situation.

Testing and final setup

Once the new snail is installed or the sling is screwed, take your time to reach full capacity. The first test should be in calm water, away from other vessels and bathers. Go to a mode close to sleeving, and assess the behavior of the boat. Pay attention to the angle of the differential: if the nose is upwards too much, you may need to move the loads (battery, anchor, passengers) closer to the nose or change the angle of the motor.

Check the engine at different revs. Listen to any extraneous vibrations that might indicate the resonance of the fasteners. Check the mounting points of the transom to the cylinder, see if there is any evidence of tissue tension or deformation. Walk through the water with a snake, check for controllability. The boat should respond to the rotating of the rummuler predictably, without sharp rolls or yaws.

If it's a success, you can go to more serious tests, accelerate to maximum speed, check if the screw is breaking into the revolutions on the wave, assess comfort: does the wave hit the bottom harder than before, sometimes lifting the transom changes the nature of the impact on the wave, making the stroke more rigid, in which case you may need to adjust the pressure in the cylinders or redistribute weight.

The final touch is the marking. If you've changed the boat's parameters, it makes sense to write down new data (maximum power, seating capacity, as changes are made) and keep it on hand. Regularly, once a season, audit the transom fastener, tighten the nuts and check the condition of the paint coating for chips and corrosion.

How often should I check the lifted transom?

A check of the bolt tightening should be done before each release in the first month of operation, after which, if there is no vibration, a monthly inspection is sufficient, however, after any hard blows to the wave or dragging the boat along the shore, an extraordinary check is required.

Can I lift a transom on an inflatable floor boat (BBB)?

You can, but with great care and minimal lift (up to 30 mm). It is advisable to use additional rigid stringers or reinforced floorboards to compensate for the increased load on the aft and avoid deflection of the bottom.

Does the lifting of the transom affect the guarantee?

Yes, in most cases, any interference with the design of the power kit or the replacement of the standard transom with the original removes the boat from the warranty. Manufacturers are not responsible for the breaks of the seams, if it is established that the cause was artisanal modernization.

Which material is better for the space: aluminum or plywood?

Aluminum is preferred because of its lower weight and absolute water resistance. Plywood is heavier and requires perfect protection, but it is cheaper and easier to process at home without special equipment to work with metal.