What Is Proedure To Repair A Hol

Technical Staff Report

First, we will classify the types of holes we are discussing as ones that are round and have been machined, probably with a drill, as opposed to punctures and cracks incurred from damage. The reasons they may need to exist repaired are numerous: refitting, resizing, removing obsolete equipment, or mistakes. When repairing fiberglass boats, the claiming is to determine an appropriate repair strategy. You want a repair that is safe and acceptable, but also realistic. You lot want to ensure that the repair is strong enough for the predictable worst-instance load and err on the side of being conservative. Other things to consider include the costs in time and money and the skill required to perform the repair.

Few repairs are identical, and many variables can influence the appropriate repair strategy. In a best-case scenario, a repair tin can be very simple: force thickened epoxy to fill up the hole, scrape it affluent, and permit the epoxy to cure. At the other farthermost, a repair of structural fiberglass might involve grinding both sides, bonding in reinforcing fibers, sanding the entire repair affluent, gelcoating, and finishing to a high gloss. The first job could have ten minutes and the latter many hours, if non days. There is no tidy repair sequence for all pigsty repairs. First, you need to call back carefully about each hole. The chart in a higher place and this word of unlike types of repair strategies from the simplest to the nearly complex tin assistance you decide the best repair strategy for most pigsty repairs.

Utilize this chart past finding a vertical line on the graph that balances both hole bore and laminate thickness. Determine the consequences of repair failure and find a horizontal line that represents the level of risk. Where the lines intersect will make up one's mind the importance of repair strength. Repairs that are in the upper right corner need to exist done very conservatively, and repairs that are in the lower left corner can place a lower emphasis on strength. The chart also demonstrates the relationship between thickness and hole diameter. A hole with a big bore is more highly stressed in a thin laminate than in a thick laminate.

Go on in mind that in all repairs, regardless of materials or technique, bonding areas must be Clean and Dry out and either POROUS or SANDED to provide molar for good adhesion.

Make clean surfaces with an appropriate solvent to remove oil, grease, wax, sealants or other contaminates. Use a heat gun or hair dryer or allow bonding surfaces to dry thoroughly. Sand non-porous surfaces with 80-grit paper to provide a texture the epoxy tin can "key" into.

Zone one—Low-take a chance repairs using thickened epoxy

The following two examples can be repaired with thickened epoxy because their characteristics put them in the lower left-manus corner of the nautical chart. They require no additional fiberglass reinforcement.

Case # 8 self-tapping spiral (only over 1/8″ in diameter) is removed from the deck of a boat. The deck is 1/8″ thick fiberglass skin with a plywood cadre.

This is a depression-risk repair. The hole is small in bore, the skin is relatively thick compared to the hole diameter, and the skin is backed by dense cadre material, plywood. If this repair fails, the worst thing that volition happen is the plywood cadre may rot someday.

To begin the repair, ream the hole with a drill bit slightly larger than the existing pigsty to expose make clean, fresh laminate and wood. And so chamfer the hole with a countersink. Do this on both sides of the pigsty if you tin can reach the backside. The chamfer softens the abrupt border left from the reaming performance so the repair is less likely to telegraph through the final terminate. Additionally, when the hole is chamfered on both sides, a mechanical lock is formed when the hole is filled.

In thicker laminates, removing the screw may result in a blind hole, a hole that does not go completely through the laminate. In this case, utilise a syringe to fill up from the bottom of the blind hole. If the hole is deeper than the length of the syringe nozzle, use a soda harbinger to extend the length of the nozzle. Trying to forcefulness thickened epoxy into a bullheaded pigsty with a putty knife always leaves an air bubble at the bottom of the hole. Filling from the bottom forces all air out of the hole.

Apply 404 Loftier-Density Filler or 406 Colloidal Silica Filler to thicken the epoxy. Fiberglass laminate is hard and strong and using 404 or 406 Filler creates a hard, strong epoxy filler, which more than closely matches the characteristics of the laminate. A word of caution: These fillers make epoxy hard to sand. When you make full a hole, clean up around the pigsty as thoroughly equally possible to minimize sanding time.

Follow the standard two-step bonding techniques. Commencement wet out the hole with cracking epoxy. Even though this hole repair example is considered a low-risk repair, any repair that has the potential to permit water into your boat deserves the best possible bonding techniques. You lot will be able to sleep better at dark if the repair is done correctly.

Example A ½" diameter hole passes through the transom below the waterline. The transom has a fiberglass peel on both sides of a two″ thick plywood cadre. There is no admission to the backside of the hole.

This pigsty has a adventure factor similar to Example 1, that is, depression-risk, beneath the waterline. Information technology is low risk because the hole is deep and at that place is a lot of surface for the plug to bond to. In improver, the hole has very little surface expanse exposed to the h2o and then in that location is very little force per unit area trying to push the repair through the hole. Also, the hole is non located where it volition exist subject to touch or pounding.

Fix this hole past reaming and countersinking as described in Example 1. Because in that location is no access to the inside of the transom, you lot should install a plug in the hole to go along the epoxy from running through while it is curing. You can make a plug by saturating some blazon of absorptive material with epoxy and forcing the moisture plug to the back of the hole. Cotton assurance, foam ear plugs, foam rubber from a pillow, paper towel, Kleenex, or whatever other absorptive material will work. One time the plug is in place and at least partially cured, terminate the repair.

Zone 2—Medium-gamble repairs using solid wood plugs and fiberglass patches

The side by side iii examples are repaired through a combination of filling with thickened epoxy, bonding solid plugs in place, and using laminates of fiberglass. These repairs fall into the middle of the chart with some higher risks, larger holes and thinner laminates.

Example A 1″ diameter pigsty exists in a cockpit seat (lazarette) hatch. Information technology's a solid ½" thick fiberglass laminate with no core. The topside has a gelcoated not-skid pattern (a type of pyramid). The underside is non an consequence cosmetically and is accessible past opening the hatch.

Although the safety hazard is depression, you lot desire a strong repair to reduce the take a chance of having the seat crevice in use and avoid futurity repairs. The most difficult part of this repair will exist the time consuming work of matching the color and non-skid design of the gelcoat surface after the hole is filled.

Sand the inside surface of the hole to expose clean laminate. Also sand a iii″ diameter area around the pigsty, on the underside of the laminate. Chamfer the top lip (the gelcoated side) of the pigsty, about ½" back, with a countersink flake or a rotary annoying tool.

Wet out these areas by applying a glaze of unthickened (bully) epoxy. And then wet out a piece of fiberglass cloth 2½"-3″ in diameter and apply information technology to the sanded area on the within of the hatch. Allow information technology to cure to a soft gel. And then fill the pigsty affluent with the surface, using epoxy thickened with a WEST SYSTEM™ loftier-density filler.

If matching the non-skid pattern is of import to you, we recommend flexible non-skid mold patterns that are available for molding the exact pattern over the repair.

Example An instrument is eliminated and now a 2″ diameter hole exists in a bulkhead, which is fiberglass with a plywood cadre.

Although it is a larger pigsty, this is not a high-gamble repair since the pigsty has existed without weakening the boat and is not underwater.

Sand the inside of the hole to expose make clean wood. Cut a ii″ diameter wood plug that matches the thickness of the original plywood core. So dry fit the plug to assure a loose fit. Remove the plug and sand a slight chamfer around the perimeter of the hole on both sides of the bulkhead that flares out onto the fiberglass a ½" or so. Glue the wood plug in place with epoxy thickened with 403 Microfibers. Let information technology to cure to a soft gel earlier filling the low spots on each side of the bulkhead. Fill the low spots on each side of the plug with a layer or two of 6-12 oz fiberglass material if the area will be exposed to bear on or abuse.

If the surface area will non be highly stressed, you can fill the low spots on either side of the plywood plug with epoxy thickened with 407 Depression-Density Filler or 410 Microlight™. Allow the epoxy to cure earlier sanding polish, sealing with a coat of epoxy, and painting or gelcoating. Refer to Finishing, Section 2.ii of the Fiberglass Boat Repair & Restoration transmission for information on painting and applying gelcoat over epoxy.

Example A ane″ diameter pigsty drilled near the hull bottom through a structural laminated fiberglass bulkhead with a ½" plywood core. Bilge water should non exist allowed to catamenia through the hole.

Since the repair is to a structural component and needs to be watertight, the consequences of failure are higher than the previous examples. While information technology is likely that just filling this pigsty will provide enough strength, overlaying the plug with fiberglass will provide more forcefulness and better sealing. What is needed here is to bail in a wood plug that is a bit thinner than the plywood cadre so that once the epoxy cures you tin laminate over it and maintain the original bulkhead thickness.

Fill up the hole with a forest plug using the method described in the previous example and then bevel the laminate at 12:one ratio on the edges where the new laminate will overlap onto the original. Utilise enough fiberglass to match the thickness of the original laminate. Apply pigment or gelcoat over the finished surface.

Zone 3—Loftier-risk repairs requiring additional reinforcing

The final three examples describe repair procedures used when a more serious state of affairs would result if the repair were to fail. Each repair uses some form of reinforcing material.

Instance three″ diameter hole was mistakenly cut through the ½" fiberglass liner. No admission hole exists to the back side.

This repair would run into the criteria in the lower correct quadrant of the chart. It is a relatively large hole, and liners are generally thinner laminates even though they frequently provide a structural component to the hull. While the consequences of a complete repair failure would be quite low, it would withal exist a good thought to repair this hole past grinding a 12:1 bevel around the circumference of the pigsty and laminating in a layered fiberglass patch, equally described in detail in our manuals.

A capitalist plate may exist necessary to keep the layers in the patch from pushing through the hole. A simple way to make a backer is to wet out a piece of lightweight fiberglass on a canvass of polyethylene plastic and let it to cure. You can then easily cut this unmarried thickness of glass with scissors to a size larger than the hole and bend it to fit through the pigsty. Bail this backer plate to the inner surface of the laminate with G/five Five-Minute Adhesive. You can then lay the fiberglass patch in place without pushing through, squeegee it down and allow it to cure. Then prepare this surface for fairing and finishing.

Example A seacock is being replaced with a smaller bore ane. It is located below the waterline. The hole is 2″ in bore and through solid fiberglass laminate of ½" thick. The new plumbing equipment requires a one½" diameter hole. Access to the back is good. The lesser is painted with antifouling paint.

In situations similar this, where the deviation in hole bore between the old and new pigsty is ½" or less and the screw pattern for the new thru-hull will be in the original laminate, you lot tin go abroad with calculation minimal reinforcement from one side. To do this, sand the inside of the pigsty to betrayal clean laminate, sand the laminate on the backside (4″-five″ bore expanse centered over the original hole), and apply the reinforcement. The reinforcement could be a layer or two of fiberglass cloth with epoxy, a sparse layer of cured fiberglass laminate like 1000-10, or a ½" thick piece of plywood sealed with epoxy.

When the epoxy used in your reinforcement has gelled, utilize epoxy thickened with 403, 404, or 406 filler to fill up the hole. Later the thickened epoxy has cured, use a pigsty saw to cutting the new pigsty. Dry out fit the new thru-hull plumbing equipment, trimming the fiberglass equally needed. Use the fitting as a template for locating the new screw holes. Be sure to seal all exposed fiberglass edges and drilled holes to prevent moisture from wicking into the laminate before installing the fitting with a flexible sealant similar 3M™ 5200.

Instance A seacock that is located beneath the waterline is existence relocated. The hole is two″ diameter through a solid laminate ½" thick. Admission to the backside is good. The bottom is painted with antifouling paint.

The chart would place this repair in the upper right quadrant due to the hole's location-a hole beneath the waterline certainly raises the consequences if information technology fails- yet, considering this is a machined hole and not a puncture or impact hole, the repair should be easy to reach. The get-go step is to sand the inside of the hole to expose fresh laminate. Next, pour some mixed epoxy into a two″ bore loving cup to form a "puck" when cured that is about 1/8″ to 3/16″ thick. Sand the border of the puck and both face surfaces, and so dry fit the puck in the hole and then that it is centered with regard to the thickness of the laminate. You tin can then bond the puck in past brushing a thickened mixture of epoxy and 406 Colloidal Silica on the inside of the hole and the edges of the puck. If the puck fits loosely and doesn't stay where placed, use duct tape to hold it in place until the epoxy cures.

Now grind back about 1/eight″ to iii/sixteen″ (depending on how thick the puck is) thickness from the laminate on both sides of the pigsty on a 12:one bevel. This will requite the beveled area about 5″ bore. Fill the beveled area on both sides with a layered fiberglass patch and epoxy. One time the patches cure, sand them and an area larger than the patch to prep for fairing and finishing. It is specially important to remove all the antifouling pigment anywhere epoxy will be practical because epoxy will non stick well to most lesser paints.

We hope the chart and the repair methods described in these examples volition assistance yous decide how to repair a pigsty. See as well our Fiberglass Boat Repair and Maintenance Manual for information on fairing and finishing as well as laminate repairs. By advisedly weighing the particulars of the hole and the importance of the repair, you can make a audio decision on what repair method to choose. This volition enable your boat to one time over again be a hole in the water (with a few less holes) into which to cascade coin!

Source: https://www.epoxyworks.com/index.php/repairing-machined-holes-in-fiberglass/

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