Thermal Fatigue Gelcoat Cracks
Short, random cracks are called crazing.
The environment can dramatically affect gelcoat. Wax can protect it from fading but there is no way to protect gelcoat against the repetitive expansion and contraction of temperature change. This movement can cause cracking, which may appear in a parallel or a random pattern.
Parallel patterned cracks will vary in length from short to several inches and are a few to several inches apart. I have heard them referred to as old age cracks. Often these are caused by an expansion of the deck laminate, making the gelcoat more susceptible to flexural stress.
Short, random cracks are also referred to as gelcoat crazing. Crazing can be localized to a small area or completely cover a deck. I have seen cockpit soles that remind me of a shattered car window. Crazing is caused by the gelcoat expanding and contracting over a given area.
We get customer calls asking if sanding the gelcoat and rolling epoxy over it will fill the gelcoat cracks and prevent them from returning. Sadly, the answer is no. Cracked gelcoat should be removed. After gelcoat removal, sand the fiberglass laminate with 80-grit sandpaper. After sanding, make any needed repairs to the area. Roll on a minimum of three coats of WEST SYSTEM® Epoxy to seal the fiberglass before applying a finish coat of paint or gelcoat.
After the repairs are completed, some boats remain crack-free for years. Taking your time and doing the job right will pay dividends in time and money.
How To Apply Gelcoat To A Boat
- Written by Luci Small on Feb 11, 2010To ensure our content is always up-to-date with current information, best practices, and professional advice, articles are routinely reviewed by industry experts with years of hands-on experience.Reviewed by
If you own a boat, you may know that it is important to give your boat a gelcoat cover to help protect it from leaks and cracks. Fortunately, with the right tools most anyone can conduct this process, allowing you to save money from hiring a professional to do it. Gelcoat is a resin that will protect any fiberglass structure with a strong shield. This resin will help protect water from seeping in even if your boat scrapes against something causing gouges or nicks. Though the gelcoat will help prevent your boat from further damage, it is important to remember that you may still need to make repairs to the boat and not just rely on the gelcoat.
Step 1 – Clean Your Boat Thoroughly
The first thing you will need to do before applying gelcoat on your boat is to make sure your boat is completely cleaned. If there is dirt or other grime on your boat when you put your coating of gelcoat on, it will not create a strong seal, which is important to the protection on your boat.
The easiest way to clean a boat is to spray it down with water than use a boat cleaning solution on the base of the boat, making sure you get everything off.
If you have used a gelcoat coating in the past, you will need to remove it completely with an acetone solution.
Repairing Minor Gelcoat Cracks
If the gelcoat cracks were caused by fiberglass flexing, add some fiberglass reinforcement to the backside to help prevent future cracks.
If a screw hole repair has a fiberglass core behind it, seal the core with epoxy. With balsa or foam core, use a bent nail to remove a small amount of core from behind the fiberglass, then fill the area with 105/20X thickened with 404 High-Density Adhesive Filler. For plywood or other wood core, make an oversized hole and fill it with 105/20X and 404 High-Density filler. Both methods provide a good seal on the core and more holding strength for the fasteners. For greater detail on fastener bonding, read the Fiberglass Boat Repair & Maintenance manuals section on hardware bonding or visit westsystem.com/hardware-bonding.
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Can I Use A Roller To Apply Gelcoat
You may either roll the gelcoat on, like paint, or spray it on, to apply the gelcoat. If you want to roll on a gelcoat, be sure to use a 1/8 or 14 solvent-resistant nap. Be sure not to use foam rollers because they tend to leave the bubbles. If you brush on the gel coat, make sure to use a solvent-resistant brush.
Crazing In Gelcoat Also Known As Spider Cracks Or Stress Cracks Plagues Countless Boaters Here’s How To Fix The Problem
Crazing is an incredibly common issue on modern fiberglass boats, and although it usually starts off as a matter of cosmetics, in severe cases these surface cracks can grow, deepen, and eventually threaten your boat’s structural integrity. They usually form in areas where the fiberglass is under unusual stress , or in areas where significant impacts have occurred, such as rub-rail collision zones or where a heavy object was dropped. You’ll want to fix them quickly because they can grow worse over time but don’t worry, it isn’t a hard job. With a little bit of know-how and a few basic tools, you can tackle this task on your own.
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Fixing Gelcoat Gouges: How To Make Them Disappear
Finding a scratch in the gelcoat of your ship is enough to create a sinking feeling in the pit of your stomach, right? That feeling is multiplied by ten when those scratches become gouges. Your pride and joy may be damaged, but it doesnt have to stay that way. No matter how much you paid for your personal watercraft, fixing gelcoat gouges is easier than most boat owners think.
What Is Boat Gelcoat
Gelcoat is a special coating applied to the fiberglass on your boat and is manufactured by mixing epoxy, polyester resin, a catalyst and other chemicals. It has little structural value. However, when combined with fiberglass, it provides a smooth and durable surface that reduces hull weakening from water intrusion and ultraviolet light.
Gelcoat is applied during the molding process of the fiberglass hull for the boat. When it comes out of the mold, it is on the outside of the hull. In many cases, a pigment is blended with the gelcoat to give the boat a colored, glossy surface.
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Identify The Boat Finish
Gelcoat cannot bond to a painted surface, so it is vital to identify the boat finish before beginning repairs. Boats that already have gelcoat, fiberglass, or polyester resin surface do not need any additional steps before repairing. Painted boats will need to have the paint removed before applying the gelcoat.
How To Apply Gelcoat
Below you will find a detailed gel coat preparation guide on how to apply gelcoat to your boat, RV or other surface. The secret to a good finish is to apply gel coat properly. The application of gelcoat is pretty straight forward when you follow this guide.
Determine the Existing Surface: First thing you want to do is look at the surface on which you want gelcoat applied. If the surface is already coated with gelcoat, or if the surface is a fiberglass or polyester resin, then the application of gelcoat is a snap. If the surface is paint then the paint should be removed before the gelcoat is applied.
Prepping the Surface: Remove rails, cleats, louvers, snaps, striping tape, etc. Duct tape off adjacent gunwale molding, and deck fittings you are unable to remove. **NOTE** Duct tape is recommended over masking tape because it provides better protection. Remove seals from the edges of parts or fittings when doing a repair around that part or fitting. Take steps to cover and protect the rest of the boat before starting. When working on the deck or cabin, tarp off the adjacent areas. 3M and UV tapes , and masking papers are recommended.
Gel Coat Additives: You should also determine which additives that you will use with your gelcoat application.
IMPORTANT GELCOAT APPLICATION TIPS:
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Ensuring The Best Results
For best results when using , do not apply in direct sunlight or when the gelcoat surface is hot to the touch. Marine Polytrol is designed to restore pigment, color and shine to the gelcoat, so it is not suitable to be used on white surfaces.
With Marine Polytrol, maintenance is easy. The results are long-lasting but when you see they are fading, simply repeat the easy process again.
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How Long Does A Gelcoat Last
Did you know gel coats can keep your boat looking glamorous for up to 10 or more years? Give the old looking hull surface a new gel coat layer and forget worrying about it, as it will last you more than a decade provided you give it the proper maintenance.
All it takes is to apply a wax layer every three to four months, wash the hull with marine boat soaps, and store the ship in cool, dry places away from sunlight.
Just using a good quality carnauba wax, sealant, and fiberglass stain remover often will save the hassle of a labor-intensive Gelcoat job.
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What Causes Gelcoat Damage
Gelcoat damage can include the following issues:
- Scratches
- Blisters
- Crazing
Problems occur for a variety of reasons. For instance, poorly applied or badly scratched gelcoat can lead to water permeating your fiberglass. Knocks and scratches to your fiberglass can be a common occurrence, along with gelcoat staining from seaweed and other water plants and general weathering and spills on deck. Removing stains with harsh products designed for household use can take the coating right off your fiberglass.
Applying Wax To Restore The Gelcoat
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What Are Gelcoat Blisters
Like anything else, you first have to understand what youre dealing with before you can begin repairs. Gelcoat blisters form when water passes through the gelcoat. It then creates a chemical solution with the interior materials that keep it trapped inside. As you might imagine, the result is both unsightly and bad for your boats performance.
If you leave gelcoat blisters be, even more problems can develop over time. When left untreated, you may have to remove the entire gelcoat altogether. This is not only an expensive process, but it will cost you plenty of time as well. The best way to repair gelcoat blisters is to identify them when theyre still isolated.
How To Fix Cracks In Gelcoat On Boat Surfaces
Gelcoat cracks indicate that your boat has suffered from severe structural problems or impact damage. As such, you need to address cracks in gelcoat on boat surfaces immediately to prevent them from spreading. While it is possible to fix these cracks yourself, your best option is to hire a contractor to fix the cracks. A professional seal ensures that the job is performed properly and meets industry standards.
In addition to fixing the cracks, you may also need to explore the reason for the cracks. If there is damage somewhere else in the boat, you need to fix the damage to prevent further cracks from occurring. If you have any further questions about how to fix cracks in your boats gelcoat, contact Pensacola Shipyard today. Our marina has everything you need to repair your vessel.
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How To Fix Gelcoat Gouges
I wrote recently about how to about fix light scratches in gelcoat, and also outlined how to find gelcoat suppliers. But what if youre looking at a used boat with deeper scratches? Whats involved in fixing them? Well, first, the process involves bargaining for a lower price than is advertised. Once you get it home, heres whats involved in bringing it back.
If your scratches are big enough to require spraying on gelcoat, but you dont have a compressor with a water separator and a paint gun, you can still make the repairs in your driveway. Most automotive paint stores sell the Preval sprayer, a paint gun that uses a disposable can of propellant and a reusable glass jar for the gelcoat. It allows novices to use professional materials and get good resultsand its a snap to use.
If you havent spray-painted anything, Preval has a YouTube channel with gobs of instructional videos.
You will have to add the proper ratio of peroxide hardener when using gelcoat, and there are dire consequences if you add too much: It catches fire. Chlorinated products, such as bleach or pool chemicals that come in contact with gelcoat have the same effect.
The rule of thumb is 4 cc of hardner for 1 pint of gelcoat, or 30 cc per gallon. However, mix only what you plan to use and read the label before mixing. If you add hardener to the whole quart, the gelcoat will kick off right in the can and harden.
RESOURCES
How To: Fibreglass Boat Repair: Six Steps To Fixing Gelcoat Blisters With Six10 Epoxy30th November 2015
What do you do when you find blisters in the gelcoat of your boat? Leave them and hope they may disappear? If you do that, you could be creating a bigger fibreglass boat repair job for yourself in the future.
Blisters in your fibreglass boat dont have to be the end of the world but leaving them to their own devices could cause deterioration.
Blisters can lead to a far more extensive fiberglass boat repair than you mightve been prepared for.
Blisters can lead to a far more extensive fiberglass boat repair than you mightve been prepared for, with your hull needing a full gelcoat removal and a whole new barrier coat applied a great deal of unnecessary and entirely avoidable stress.
The solution is WEST SYSTEM® Six10® Thickened Epoxy Adhesive. Follow these simple steps and youll be able to perform a repair job on gelcoat blisters in no time.
How does Six10 Thickened Epoxy Adhesive work?
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How To Prevent Gelcoat Cracks
As a rule, it is almost impossible to prevent gelcoat cracks. Time, use and the elements will eventually have their way with the hulls surface, leading to radial, linear or thermal cracks. However, there are some things you can do to either prevent early cracking or the expansion of a single crack.
For instance, you can countersink holes through the gelcoat. This method redistributes the stress onto the structural fiberglass and not the fragile gelcoat. When holes are drilled correctly, you can preserve the gelcoat longer without cracking or chipping.
How To Avoid Gelcoat Stress Cracks
Spider cracks can be avoided by countersinking holes just through the gelcoat, so the load is placed on the structural fiberglass rather than the brittle gelcoat. Theres also a great article on how to drill holes correctly to avoid chipping and cracking in fiberglass.
Quite often however, its near impossible to prevent these unsightly cracks due to the fact gelcoat is so brittle and rigid.
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