DIY plastic boat hull repair

This is not so much an article as knowledge gained in practice in the form of notes.

I started repairing plastic back in my sporting days. When, at the moments of hard drinking, the whole base brought oars to me for repairs, and then boats. Since the boats were beaten often, I had a good opportunity to gain a lot of useful knowledge empirically. Which were then actively used in the repair of hulls of motorboats, boats and yachts.

The main materials for the repair of plastic housings are epoxy resins and various glass fabrics.

There are a great many epoxy resins in the world. Basically, they are all very resistant to external influences after curing. But, as always, you will not find the best thing. Or it stands like a cast-iron bridge. Experiments have shown that for ordinary household compounds, EDP and EKF, as well as automotive epoxy putty (which is also some kind of EKF), are quite suitable for repairing housings. The main thing is that there is an appropriate hardener. EKF after curing gives a more plastic layer. All kinds of industrial compounds, from the category “two buckets of epoxy and a bucket of hardener” are also suitable, but for repairs they are usually not needed in such quantities as they usually are from the factories. And they are extremely toxic. You can get an allergy, or you can get a poisoning of the type of BOV skin-blistering action, smoothly turning into eczema.

Epoxy is best handled outdoors or in a well-ventilated area and wearing medical gloves.

Ideally, epoxy is diluted with a hardener according to the instructions. But experiments have shown that if you stir well, then the compound will set even with a small amount of hardener. It will only grasp for a long time. And the layer will be more plastic. Accordingly, and vice versa. However, the more hardener, the harder and more brittle the layer.

Video (click to play).

Sometimes a filler compound is needed for work. At the worst, even dry fine sand can be used in the field. But it is better to buy or otherwise have ground mica or silver. Don't blow silver. It will be worse for you.

If the hardener is not poured into the resin, you can get a lot of problems. The resin usually heats up slightly when the hardener is added. But in my practice there was also the release of some kind of stinking smoke and combustion and just stinks.

Some epoxy grades melt perfectly after curing at a temperature

150 degrees. This can be used if it is necessary to remove the compound from the non-combustible material.

If the compound is heated during polymerization, then it sets faster. We remember the hairdryer.

If it is necessary to press down on the surface covered with the compound, then it is enough to put a sheet of cellophane, polyethylene, and preferably fluoroplastic on top.

Fiberglass is different. I'm not a brand specialist. Therefore, I will explain "by eye". When repairing, you mainly need fabric with an average thread size. Preferably with "oblique" or satin weaving. But the usual one, with a “homespun” weave, will also work. In rare cases, you need a glass wool or glass fiber. They are the same in the thickness of the threads. Differ in weave. For those cases when you need a thick fiberglass weave do not care.

The fiberglass we need should be twisted threads. Will not work with whole fibers. If you shake it, then a cloud of glass pieces should not fly out of it. An operation such as shaking a large piece of fiberglass is best done where there are no people. Downwind. And holding my breath.God forbid you breathe or shake this muck into your eyes or anyone else.

Fiberglass comes in sheets, rolls and tapes. This is a big deficit in sheets. That is, each piece is sealed from all sides. The roll is sealed on only two sides. In principle, the tape is the same roll, but narrow. Usually comes with the most convenient oblique binding, but rarely comes across more than 5 cm.

Currently, fiberglass of various brands is quite often sold in ordinary building materials stores. You can also buy fiberglass from various construction organizations, for example, those involved in the laying of heating mains. Well, or he will come to an agreement with those men who are wrapping this heating main.

To work, the glass fabric must be dry and fat-free. In the field, you can quickly dry fiberglass by calcining it well on a sheet or in a bucket. It will not burn. It is better not to dry over a fire. God forbid it gets smoked. Fiberglass is degreased by rinsing it in any solvent.

Fiberglass must be impregnated before sculpting somewhere. It is necessary to impregnate by repeatedly immersing the workpiece in the diluted compound. After each immersion or “kneading” in the compound, the workpiece must be squeezed out. For example, stretching it between two tightly compressed sticks, tubes, fingers, etc.

The housing must be clean, dry and free of grease before being repaired. In places of repair, of course. in some cases long drying is required. Better with a technical hairdryer. But the hairdryer of your beloved wife and the usual home fan heater will also work.

Typical damage to plastic: 1. damage to the decorative layer 2. cracks in the case 3. “half-holes” 4. holes 5. diverging “corners” 6. shells 7. all this together

Damage to the decorative layer - minor damage. A scratch that does not damage the layer through and through is simply primed with GF primer or epoxy without filler. It is sanded and painted over. A through scratch, even if the case itself is shallowly touched, is putty with a compound with a filler. It is sanded and painted over. If the decorative layer falls behind, then it must be peeled off to the point where it is firmly adhered to the body.

The inside of the case is usually just painted. This is true. On a note.

Never work on the edges of holes. Let them frown better. It will be stronger.

Where the fiberglass will lie, the case should be cleaned along the first layer of fiberglass on this side, so that this layer is slightly brushed. Even if it was torn in places. This is best done with a coarse sandpaper wrapped around a block of wood, cork or finely porous foam.

The fiberglass sheet must be glued so that the edges are smoothed out and do not fall on the paint or decorative layer.

It is better to take your time when working. And in advance, figure out how to put the body in the right position. Bo is most convenient to do something if the working area is horizontal. And if there is a need to glue a large piece of fiberglass, then the only way to put it right is to place the surface horizontally or close to horizontal.

Half-hole is vile damage. This is a break in the case in which the piece of plastic remains mostly attached to the case. Not with a flap, but more precisely. In general, an abomination. We clean on both sides. Then we figure out whether we will be able to put the piece in place. This usually works with small breaks. If there are no chances, then it is better to remove the piece. Get a normal hole and repair as described below. If the piece itself is damaged, then you also need to remove it. But you can try to straighten it. We coat all surfaces with compound and put a good stop on the side of the direction of impact. Preferably with a thick rubber gasket. On the other hand, with a mallet, carefully put the piece in place. It will never work exactly in place, but you have to try. As a result, we get a dent on one side and a bulge on the other.Immediately place a soaked piece of fiberglass on the bulge. And we fix it with a spacer or load. When everything is polymerized, we begin to process the dent. Putty with resin with filler. After hardening, we grind. We glue the impregnated sheet. We grind. cover with a thin layer. We grind and paint.

For a good seal of the hole, a punch must be made. For example, from foam. This is necessary in order not to disturb the contours. Better if it is a punch along the outer contours. This is exactly the case when thick fiberglass is needed. We process the edges. That is, we remove the paint and lightly brush up our native fiberglass. We cut out several patches from the glass crimp, with a minimum (3-5mm) overlap covering the hole. The number of layers should be chosen by eye on the assumption that the thickness of the package should correspond to the thickness of the case. We put the punch. We glue the patches in layers. Each layer is allowed to dry until the resin is semi-polymerized. And no bubbles. After that, from the inside of the case: grind, glue another layer, grind, second layer, grind, cover with a layer of pure resin, grind, paint. Put one layer outside and process it in the same way.

The separated corners are glued in the same way as for sealing cracks. But it's best to use tape for them. It is advisable to put the corners in the transom on the knits. Knits are made of plywood or plywood tank. They are carefully adjusted according to the mating angle. First, the knit itself is glued in. Then it is pasted over with fiberglass. For example: on the transom of Ladoga-2, two knits with a side of 100 mm were placed at the joints with the sides. At the bottom joint, three on each side. Of course, all the places where the fiberglass fits are thoroughly cleaned to the first native layer.

No one has come up with anything more disgusting than shells. The shell in the laminated plastic is either a factory defect. Or is it the result of water getting between the layers of the hull. This usually results from damage to the outer layers. After a couple of hibernations, the freezing water expands the layers. If this shell is closer to the inner side, then we can assume that the entrance to it is from the inside. It's better to score on such damage. If it is closer to the outside, then it must be repaired. The main problem is that the sink is very difficult to dry. therefore, in order not to wait a month in the sun, the sink needs to be opened. From the side of water entering it, we drill a hole

8-10 mm. Depth before entering the cavity. With a wire or any other thin and flexible object, we determine the true dimensions of the shell. We open the shell with a knife or "claw" from a hacksaw blade. We make it wide enough, up to 5 mm. cut along the largest shell size. Several parallel cuts are possible. If the width of the sink is more than 100-120mm Through the cut with a dry hair dryer. Then we drive in as much compound as possible with a syringe. The most important thing is that the sink must then be clamped over its entire area in some kind of press. Or strut and support. Or with a clamp with large coverage. Or a load. Well, the favorite process of putty is sanding and painting after polymerization.