Cart 0

How to Gelcoat a Boat with the Preval Sprayer

boat gelcoat how to preval preval sprayer



MHaving a High-Quality Gelcoat Reflects Well on Your Boat’s Value


Yachts, powerboats, jet skis and other amphibious vehicles are coated with several layers of gelcoat to protect the fiberglass hull from wear and damage. Gelcoat is a strong resin that adheres to the contours of your boat and flexes with the hull's contortions as it tackles the waves and weather.

If you get a lot of enjoyment out of your marine vehicle, its hull is destined to suffer some wear. Regular docking, unforeseen events, and heavy sunlight can take their toll. Even a few small blemishes can have a negative impact on the resale value of your nautical vessel. Professional hull scratch and gelcoat repairs can be expensive and inconvenient, so consider fixing it up yourself with a few simple tools and a Preval Sprayer.

Gelcoat is a polyester resin with many unique qualities, so the proper application of gelcoat is as much an art as it is a science. Regardless of your skill level with gelcoat application, the consistent spray pattern and portability of the Preval Sprayer is an ideal tool to gelcoat your boat’s repair touch ups.



• Do not gelcoat if the temp is below 65 or above 80 degrees Fahrenheit.

• Use sanding blocks, not paper, for a more even finish.

• When filling corners and small chips, use acetate instead of bondo or lacquer filler.

• Never spray gelcoat in direct sunlight during a hot day. The material will dry too quickly, resulting in cracks and/or a dull finish.

• Do not use wax-lined cups for mixing gelcoat, epoxy or resins, as these will leave small shavings in the mix and disrupt your Preval sprayer.

• Do not use any filler with fiberglass strands added.

• Clean the Preval Sprayer by spraying through the unit with acetone, then save for later use. 



Solvent-resistant gloves

Eye protection


Preval Sprayer

Gelcoat and hardener (matched to the make and color of your boat)

 Scraper, grinder or Dremel tool

Sanding blocks with grits #220, #320, #600, or #800


Paper towels or clean rags

Auto-body filler, lacquer putty or acetate + applicator


Polishing compound



Gelcoat Scratch Repair: Preparation

1. Wear a respirator and eye protection to protect against fiberglass dust and the gelcoat fumes.

2. Grind out loose fiberglass and gelcoat with a Dremel, drill or grinding tool.

3. Water sand on and around the scratch to eliminate all loose gelcoat.

4. Block sand the area and several inches surrounding it, starting with heavy grit to get chips and other loose materials, then moving to finer grits until the scratch and surrounding area is smoothed out.

5. Brush off the sanded surface, then clean it with acetone, using a one- direction wiping motion and paper towels or a clean rag to ensure the dust isn't smeared in.

6. Fill the scratch with auto body filler, lacquer putty or fairing compound. Apply as much as needed, thinly and evenly. Wipe away the excess but leave enough to allow for sanding, then let dry.

7. Sand the filling compound with #600 or #800 grit block then brush and wipe away all dust. Ensure the filler is even and smooth. If another coat of filler is needed, repeat Step 5.



Gelcoat Scratch Repair: Application

1. Mix gelcoat compound with hardener according to instructions, then pour the mixture into the Preval sprayer bottle. Thin with a small amount of acetone to allow for an even spray.

2. Keeping a consistent distance from the repair area with each pass, apply an even layer of gelcoat to the sanded area then allow to dry for 15-20 minutes.

3. Repeat until a minimum of five coats of gelcoat have been applied with the Preval sprayer. (NOTE: Some gelcoat brands recommend light sanding between layer applications. Please review the instructions carefully.)

4. After the final layer of gel coat is dry, sand the area lightly and evenly with a #260-grit wet/dry block, then with a #320 and #600.

5. Finally, buff the area out with a clean buffer and polishing compound.



The Preval How To Articles Such as this one above is for informational purposes only and is intended to provide general information guidance. Because products, materials, techniques, building codes, federal, state and municipal laws vary, and are continuously changing, as is ordinances, C.A Acquisitions LLC, Chicago Aerosol and Preval assumes no responsibility for the accuracy of the information contained herein and disclaims any liability for omissions, errors or the outcome of any project. It is the responsibility of the reader (you) to comply with all appropriate laws, manufacturers guidelines, rules and regulations for any project or product used. You must also take any safety precautions and exercise caution when taking on any project and by following the MSDS warning for every product or paint used in conjunction with the project completion. If you HAVE ANY QUESTIONS OR DOUBTS IN REGARD TO ANY ELEMENT OF A PROJECT PLEASE CONSULT A LICENSED PROFESSIONAL.


Older Post Newer Post

Leave a comment

Please note, comments must be approved before they are published