How To Repair Fiberglass Hull?

By Author: Amarine
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The advantages of fiberglass are numerous and it is because of this that it is used majorly in the production lines of boats. One of this advantages is that the fiberglass can be easily repaired. Therefore, if you see any form of damage on the fiberglass hull of your boat, fret not for there is a solution.

This Tony from Amarine will guide you through simple steps, how to repair the damaged fiberglass hull such that after the repair, you won’t even see the traces of the damage.

THE STEPS:
STEP 1: SHAVE OFF THE DAMAGE
The first step in repairing the damaged hull is by shaving or cutting away the damaged area. To do this, find out how damaged the area is. You can easily do this by tapping a tool against the area to check out the sounds made.
If the sound is loud, that is the result of a solid laminate; if the sound is not so loud or it is quiet, that shows a result of delamination. Remember that a damaged fiberglass cannot be saved. With this in mind, cut the area which is damaged by using an oval or circular cut.
Now, insert the new laminate into the cut-out area.

STEP 2: REPAIR ...
... FROM INSIDE THE HULL
The second step after shaving off the damage is by repairing from inside the hull if the damaged area is not so big. Find a 12-to-1 chamfer and then bevel the edge of the hole. In a scenario where the hull is half-inch thick from outside, you will get a surface diameter of 15 inches to refinish if you repair a 3 inch hole. This is applicable if the damage area is above the waterline.
One other advantage of repairing the damaged area from inside of the hull, is that you can easily cover the hole outside the boat with a polished surface. That way, you won’t have to stress much.

STEP 3: USE A DEWAXING SOLVENT
The third step in the repair is by dewaxing. Dewaxing means removing wax from a material. This is best done by thoroughly washing the hole areas with any dewaxing solvent. The inner surface of the initial fiberglass usually have mold release traces and they need to remove them. Failure to remove them could weaken the bond made when STEP 4 is being done.

STEP 4: GRINDING
The fourth step is the grinding. Grinding is the best way to get a strong and durable repair. Why?
Before the previous layer is fully cured, each layer is applied and this allows the resin links to form a solid bond of the previous and new layers. It doesn’t matter how strong the laminate to laminate bond is, the initial bond is always mechanical. Grinding ensures that the bond made is chemical
Using a disk sander, grind a bevel around the perimeter of the hole inside the hull. In order to accommodate a finishing layer of cloth, you need to grind a rectangular area of the inner surface.
Before using the disk sander, you need to ensure that your eyes are protected by goggles and also use a dust mask to protect your lungs from inhaling too much dust. Protect your skin with long sleeves clothes to reduce irritation of the skin.
The device should be tilted on the surface in such a way that the dust is not blown towards you. When you are done, you will get a uniform dull look after wiping the area with an acetone-dampened rag.

STEP 5: MASK AND MOLD
As you continue with the repairs, the next thing you need to do is mask the area below the hole. Adding a heavy coat of paste wax will prevent any resin runs from adhering. Note: You should make sure that the past wax do not get inside the hole or the edges of the hole.
Get a scrap of Formica or Plexiglas (let’s call this backer) and make sure it is just a foot larger than the hole. Spritz with PVA mold release. After that, screw the scrap of Formica or Plexiglas (backer) to the outer surface.
The backer will follow the correct curve if the hull is flat or curving in one direction only. However, if the hull is curving in two directions (spherical), you can screw acrylic to the hull and shape it into the correct shape if a heat gun is available.

STEP 6: FIBREGLASS FABRIC
The next step is by cutting enough fiberglass fabric which will fit the hole. The laminates number required will be determined by how thick the hull is.
When it comes to cutting, the first layer of mat which is the full size of the ground depression should be considered because it will be cut. When this is done, the next pieces should be cut in a smaller inch size.
To apply the new fabric, cut the largest piece first, then cut the smaller pieces. Make use of a polyester resin since it ensures the maximization of the area of the secondary bond.

STEP 7: USING RESINS (POLYESTER OR VINYLESTER)
If the damaged area is above the waterline, you can get any of polyester resin or vinylester. If you wish to get a stronger and durable repair, using epoxy is advisable. Epoxy is far advisable for when you are doing underwater repairs.
If you wish to use the former resins mentioned, then it is advisable to get a laminating resin. Use a PVA mold release coating and sea from the air if you want the final laminate to cure.

STEP 8: CATALYST
To get either the polyester or vinylester resin to work well, a catalyst is needed. One such catalyst is MEKP (Methy; ethyl ketone peroxide)
To sue the polyester resin, you need to follow the manufacturer’s instructions. Remember that weather, temperature and thickness may determine the curing times. You can also adjust these times with the addition of more or less catalyst. For maximum return, it is best to leave the mixture overnight.

STEP 9: ADD GELCOAT
Gelcoat is a pigmented polyester resin. To begin the repair, spray or brush color matched gelcoat onto the backer which has been waxed. The thickness can be checked with a toothpick.

STEP 10: LAY-UP
Once the gelcoat is done, use the polyester resin to wet it and then compress the first and second layers of mat and one layer of cloth against the gelcoat.
Lay up four more piles once the three first piles have kicked in. To prevent weakening, do not lay up more than four piles at the same time.

STEP 11: FINISH
You are now at the last stage of the repairs. Get a cut rectangular piece of mat and a slightly larger piece of cloth. Apply them over the patch and then smoothen them with a squeegee. To get a full cure. Seal the top layer with either PVA or plastic.
Now, remove the backer. If there are any imperfections in the new gelcoat, fill them with gelcoat paste. Then wait for a full cure. Polish the area that has been repaired after cleaning the area around the patch.

Refer from the https://amarine.store/

This is Tony from Amarine company,we provide boat accessories and fishing gears.