When you have to make some cuts in fiberglass, here's how to use the correct tools and techniques to ensure success.
Easy to moderate
- Drill with bit
- Tape measure
- Marker pen
- Jigsaw with fine metal-cutting blade
- Vacuum cleaner
Depends on the hole size and location
Minimal: $2 for the jigsaw blade
The first time I had to cut a hole in my new boat was so nerve-wracking. I'd just bought a compass that needed to be fitted into the bulkhead next to the companionway. What if I messed up? What if I made the hole in the wrong place?
In the end, the job worked out just fine, and since those early days, I've drilled and cut countless holes, and learned lessons along the way. As with everything in life, preparation is key, and a can-do attitude is almost as important as having the correct tools. Take your time and think through the job to ensure it turns out as intended while reducing fuss and frustration.
A hole is a hole. The one we'll cut here is intended for a new VHF radio. But the same process applies to anything that needs to be fitted into a console or other fiberglass panel: stereo, depth sounder display, chartplotter, fishfinder, or compass.
First, decide where the equipment will be installed. In many cases, choice will be limited, but try to avoid installing any electrical equipment too close to the compass, as most if not all electrical components will cause deviation in your compass heading. Then, before you cut, examine not just the face of the console but also what's on the other side. You don't want to inadvertently slice through cables that are hidden from view. Also ensure that you'll have room to make all the necessary connections once the unit is installed. Our console was made from solid fiberglass, but if you're cutting through cored material, seal the edges of the core with epoxy after completing the cut to prevent water ingress.
- Most electronics come with a template in the box. Use a pair of scissors to accurately cut out the template.
- Use masking tape to position the template on the console. Examine this from several different angles. Is it level? Will you be able to operate all the controls when installed? Once you're happy with the placement, draw a line around the inside of the template with a pencil or marking pen, take a deep breath, and move on to the cutting stage.
- The correct tools help ensure success. Almost without exception, the cutout for any equipment will be rounded at the corners, and for that, a drill is required. Choose a drill bit based on the required radius for the corners. In most cases, a sharp twist bit is all that's needed, but a hole saw can be used if the radius is large. A rechargeable electric drill makes short work of the task.
After you've examined what's behind the area you'll be cutting, carefully drill through the fiberglass at each corner. Usually you can eyeball where the point of the drill needs to be placed before drilling the hole. But a few measurements and a pencil mark will do the trick if you lack confidence. Aim to be as accurate as possible, while being careful not to creep outside the line. Better to be inside the line, if anything, as you can always cut out a little more, if necessary.
- With drilling completed, the next step is to cut between the holes. There are several ways to accomplish this. My first choice is to reach for a jigsaw fitted with a fine metal-cutting blade (pictured). Don't use a coarse blade intended for use on wood. If you do, the fiberglass will vibrate, you'll chip the surface and could crack the fiberglass laminate. The thinner the fiberglass, the trickier it can be to cut because it will flex and may crack.
- Insert the blade into one of the holes. Make sure the base plate is clean and smooth and firmly in contact with the gelcoated surface before pulling the trigger. Cut slowly and steadily just a fraction inside the line, repeating the procedure between each of the holes.
- After cleaning up any mess, fit the equipment into the new hole. If it's a little tight, you may need to ease the opening with an appropriate grade file.
- This radio came with a neoprene gasket, which was installed between the back of the unit and the front face of the console. Screws from the rear hold the radio in place and complete the installation.
TIP: Always round the corners on a fiberglass cutout. Sharp corners increase the chances of spider cracks forming.
Working with fiberglass is unpleasant at best, so use adequate precautions. Wear gloves, a dust mask or respirator, goggles, and a long-sleeved throwaway shirt to avoid coming into contact with the dust, which is toxic. Vacuum up dust immediately to avoid tracking it all over the boat.
This article was reprinted with permission from BoatU.S. Magazine, flagship publication of the membership organization Boat Owners Association of The United States (BoatU.S.). For more expert articles and videos to make your boating, sailing, or fishing better, visit BoatUS.com.