The operation of a low-pressure inflatable boat (LDPB) is significantly different from the use of hard-deck or keel models with plywood slate. The main feature is the softness of the transom and the need for a special approach to installing additional equipment, such as door-wheelUnlike PVC transoms, you can't just screw brackets through a layer of fabric, because this will lead to deformation and loss of tightness under loads.
Proper installation allows one person to easily move a motor boat across sand, rocks or asphalt to the water. However, errors in the design or drilling phase can permanently ruin an expensive boat. It is important to understand that the load of launching from the trolley is not only on the transom itself, but also on the anchoring points, creating enormous pressure to break and shear.
In this article, we will discuss in detail the process of preparation, selection of materials and step-by-step algorithm for installing the wheel stroke. Particular attention will be paid to the issues of sealing the passage places of the fastener and adjusting the height, which is a critical point for models with a high speed. float-bottomReadiness to work and having the right tool is 90% of success.
Choosing the type of fastening and preparation of the transcrete
The first step is to determine the type of attachment that will be compatible with the design of your boat. For NDNDM, two options are most often used: attaching directly to the squirrel board (if it has sufficient thickness and rigidity) or using elongated brackets covering the sides. transom board in such boats is usually made of plywood laminated with plastic, and has a thickness of 20 to 30 mm.
If you plan to attach the wheels directly to the board, you need to make sure that when the wheels are lowered, they will not touch inflatable tubes or stringers. Often you need to shift the axis of the mount below the bottom level.
It is important to consider the weight of the outboard motor. If you use heavy four-stroke engines, the load on the transom increases many times, in which case the standard "native" mounts may not withstand, and you will need a reinforced design with additional support points on the board.
- 🛠️ Direct anchorage: brackets are fixed directly to the transom board through through the through holes.
- 🔧 Enveloping anchorage: a long stud or frame running under the bottom or covering the sides is used, which distributes the load.
- 🚫 Adhesive attachment: It is not recommended for active boats, since the glue does not withstand dynamic loads on the breakaway.
⚠️ Attention: Never use wood screws or short bolts that only enter the plywood layer to attach the transom wheels to the NDND, without reaching the outer shell, which creates the risk of the bolt cap being pulled off under load.
Before work begins, the engine must be dismantled and all removable elements removed from the transom, the surface must be clean and dry, and if the boat is new, it is advisable to give it a few days to "lie down" in the straightened state, so that the folds that have arisen during storage come out.
Required tools and materials
The quality of the installation depends on the tool used. To work with composite materials and PVC requires accuracy. You need an electric drill with a speed regulator, because you can not drill PVC at high speeds - the material will begin to melt and deform.
For sealing holes, it is best to use two-component polyurethane sealants or special adhesives for PVC, such as: Loctite or Tear AidRegular silicone can detach over time from constant contact with water and vibration.
You'll also need:
Metal drill (cobalt) the diameter corresponding to the fastener.
Keyset (usually carob or cape on 10, 12, 13, 14, 17 mm).
marker It is better to drink alcohol (not to wash).
Sandpaper 120-180 grains for cleaning the edges.
And the other thing that's worth mentioning is the fasteners, and the bolts that come with the wheels are often of poor quality (soft steel), and they're better replaced with bolts made of steel. stainless steel The carving must be clean, without barbs, so as not to damage the structure of PVC when stretching.
Marking and drilling of holes
The most critical thing is the marking, and if you make a mistake of a couple of millimeters, you can get the holes too close to the edge of the squirrel board, or worse, you get into the inflatable balloon, and you can do the markings from the outside of the transom, and you can try on the bracket as you assemble it.
Put the bracket on the transom and put it strictly horizontally. Use a building level or a ruler. Mark the centers of future holes with a marker. Then remove the bracket and double check the symmetry of the markings relative to the keel of the boat.
The drilling process requires caution. Start by drilling a small diameter (3-4 mm) on the inside of the transom (on the cockpit side) to get out. This will avoid chipping the outer decorative layer of PVC. Then drill the hole to the desired diameter on the outside.
☑️ Pre-drill check
The edges of the holes must be carefully treated, and inside the boat, where the cut will be visible, you can melt the edges with a neat movement of the heated soldering iron stinger (without touching PVC), or treat with fine skins to remove the pile, which will prevent cloth bullies when you install the bolts.
Sealing and installation of brackets
Sealing is a key factor in the longevity of the plant, and water trapped between the PVC layers and the plywood through the hole will cause the transomach board to dissect and rot, so each bolt must be isolated from the environment.
The installation technology is as follows:
1. Degrease the area around the hole with alcohol or a special cleaner.
2. Apply a sealant layer on and around the inside of the hole.
3. Insert the bolt, before wearing a wide washer (enlarged washer) of stainless steel or plastic. The washer should be oiled with a sealant.
4. On the outside also apply the sealant under the washer of the bracket.
When you tighten the bolts, you're going to do it gradually. First, you're going to grab all the bolts by hand, then you're going to tighten them cross-haired, you're going to spread the pressure evenly. Excessive force can push soft PVC, so it's important to find a balance. The bolt has to sit tightly, but it doesn't sink in the material.
| Mounting element | Materials | Recommendation | Risk of error |
|---|---|---|---|
| Bolt | Nerzh steel A2/A4 | Replace with a longer one if necessary | Corrosion, cliff. |
| Puck | Enlarged (D=20-30mm) | You need to be wide for load distribution | PVC breakthrough |
| Hermetic | Polyurethane | Resistant to UV and salt water | Leakage, rotting. |
| nuke | Nerge. steel + grover | Use a self-contradicting nut | Self-twisting |
⚠️ Attention: Once installed, allow the sealant to be fully polymerized for the time specified by the manufacturer (usually 24 hours) before loading the structure or launching the boat into the water.
Adjustment of height and inclination
For NDND boats, the right height of the wheels is critical. If you put them too high, the nose will stick up when the boat comes off the trolley, and the boat can slip or flip over. If it's too low, the wheels will drag themselves through the water, creating resistance.
The optimal position is when the axis of the wheels is 2-4 cm below the line of conditional continuation of the bottom, in this case, when descending from the trolley, the boat first touches the water stern, and then smoothly slides off the wheels, which at this point are already submerged.
The angle of the bracket itself also plays a role, and it has to keep the wheel upright when moving on a flat surface, and if the boat's transom has a strong keeled curve, you might have to use adjustable-angle brackets or make oblique spacers.
Operation and maintenance of wheels
Once installed, the system requires regular maintenance, salt water, sand and silt are the main enemies of mobile machinery, and after each departure, especially at sea, the wheels and mounts must be washed with fresh water.
Wheel bearings should be periodically lubricated with moisture-resistant lubricant (e.g. lithium or graphite) if the wheels start to creak or rotate tightly, this is the first sign of lack of lubrication or dirt.
- 🧼 Washing: Wash the salt off after every trip to the sea.
- 🛢️ Lubricant: Once a season, disassemble the wheel axis and change the lubricant.
- 🔩 Pimp: Check the nut tightening every 5-10 hours of operation, as vibration can weaken the connections.
Store a boat with installed wheels can be, but it is better to remove them for long-term winter storage to remove the static load from the mounting points and the PVC itself.
Frequent errors in installation
One of the most common mistakes is to ignore the reinforcement of the attachment site. On soft transverses of NDNDM, sometimes an additional aluminum or textolite lining is placed on the inside so that the bolt does not press through the fabric during jerks.
Another mistake is to use too short bolts: the fastener must pass through the whole pie (PVC + plywood + PVC) and go out at least 1.5-2 diameter of the thread for reliable nut fixation. An untied bolt is a guarantee that the wheel will fall off at the most inopportune moment.
⚠️ Attention: Do not use conventional paint or varnish to fix nuts. Use only special thread fixers (anaerobic sealants), which allow you to dismantle the knot if necessary.
And you often forget about electrochemical corrosion protection, and if you have a boat with aluminum elements and steel bolts in salt water, the metal breaks down very quickly, and you have to install plastic bushings or use titanium fasteners.
FAQ: Frequently asked questions
Can I use the wheels without drilling?
In theory, there are powerful two-part adhesives, but for transom wheels carrying loads of several tens of kilograms with a dynamic impact on the descent, the adhesive connection is considered not reliable enough. The risk of tearing is high, so mechanical fasteners (bolts) is the standard.
What diameter of the drill is used for the M8 bolt?
For metric thread M8 usually used a drill with a diameter of 8.2 mm or 8.5 mm, so that the bolt comes in with little effort, but not dangle. However, for PVC is often recommended to take a drill exactly 8.0 mm or even 7.8 mm, as the material is elastic and slightly stretched, providing a tight tight tightening.
Do I need to put the pucks under the nut outside?
A wide washer (or several washers) under the nut on the outside of the bracket will prevent the metal from squeezing through the bracket and ensure that the structure is evenly pressed against the transom. Often using spring washers (grovers) to prevent self-twist.
What to do if the holes are already drilled curved?
If the displacement is small, you can try to drill holes under a larger diameter and use bolts with wide hats or put additional reinforcing plates (repair patches) on the inside and outside, covering the old holes. If the error is critical, it is better to contact the service for professional welding / pasting a new section of the transom.