We’ve all faced it — the dreaded “holey moley” moment. It’s that moment that you stand over your boat with a drill in your hand, contemplating the damage you are about to intentionally inflict on your vessel. Whatever the customization, upgrade or addition you are contemplating, it is going to require a hole in your boat. Even if you aren’t drilling new holes, if you own a used boat, you have probably inherited all the holes drilled by all the former owners.

Unfortunately, holes are a necessary evil for every boat owner, but there is a lot that can be done to minimize the number of holes you need, and to minimize the impact of the ones you have.


Why Holes Are Bad

It’s important to first understand the long-term problems with drilling a hole into a boat. Whether you are dealing with fiberglass, aluminum, or wood, any penetration that isn’t properly addressed can create long-term problems.

Wood Rot 

Obviously, wood rots. Most wood is sealed with either fiberglass (in the case of transoms and stringers) or some sort of protective coating such as polyurethane. The moment you drill through that protective coating, you have given water easy entry into that wood, and once in, it’s very hard to get out.

Aluminum Corrosion 

Aluminum doesn’t rot, but often behind that aluminum is wood support. Even if there isn’t, anytime you put two dissimilar metals directly in contact with each other, such as a stainless steel screw into an aluminum boat, you introduce an electrochemical process that starts corrosion. Over time, these become a festering point for future corrosion, especially in saltwater environments.

Fiberglass Delamination 

That nice, smooth, shiny gelcoat does more than dress up the ugly brown fiberglass underneath. It seals it and keeps the fiberglass from delaminating. When you drill a hole into fiberglass, you allow moisture to penetrate between the layers of the fiberglass mat, which can lead to delamination and weaken the area over time. Additionally, the gelcoat itself is subject to chipping, and an improperly drilled hole can chip the gel coat around it significantly.

Minimizing New Holes

So, what’s the solution? The first thing you can do is take steps to minimize holes and reduce the damage they create. There are some simple steps you can take to do this.

“Sacrificial” Mounting Plates

Every boat has certain surfaces where holes are likely to be needed throughout its lifespan. Consoles, transoms, gunwales, and just about any vertical or horizontal surface of a boat are generally high-demand areas for customizations and additions.

Over time, much of this equipment will be upgraded or replaced, and it’s nearly guaranteed that the hole patterns won’t match. In some cases, these aren’t just screw holes; flush-mounted electronics require large openings, but the unit you install today is unlikely to be the same size and shape as the unit you will eventually replace it with. There are simple ways to ensure that the modifications you make today can work for tomorrow.

Smaller Holes

For small screw and bolt holes, instead of drilling new holes directly into your boat for each new addition, consider a different approach. By first mounting a 1/2” or 3/4” thick piece of marine grade plastic sheeting over the area you plan to use, you will drill fewer holes into your boat (to mount the plastic sheet), and then can drill all the holes you need for equipment without any additional penetrations.

King Starboard is a popular material for mounting plates and comes in many colors to match or at least complement the color of your boat. Starboard is fairly easy to fabricate using basic woodworking tools, but pre-cut sheets are also available with radius corners and rounded over edges if desired. If over time the PVC board becomes too “holey,” you can swap out the plate by simply matching the hole pattern on a new piece.

Larger Holes

For larger openings, like cutouts for flush mount electronics, the challenge is that, when replacing equipment, the size of the required opening can change. That’s fine when you need a larger opening than you have, but not so good when you need something smaller. This is where acrylic (Plexiglass) can help. 

Mounting an acrylic sheet over your dash not only covers hold cutouts, but it also can give your whole dash a clean new look. Once again, when it is time to upgrade or replace your electronics, you can easily replace the acrylic covering as well.

Acrylic can be tricky for DIYers to cut, drill and finish, but Boat Outfitters can custom cut a rectangle to your specifications with radiused corners, rounded over edges, and polished edges.

For more complicated applications, consider a fully custom, CNC-cut dash panel you can install yourself. Another, simpler option for replacing electronics with devices that require a smaller cutout is to use a Starboard trim plate to hide the gaps. 

Again, because Starboard is easy to work with, you can cut your own trim plates at home, or you can order a custom, CNC-cut trim plate to your exact specifications. 

Sticky situations

A relatively new option for minimizing holes is to consider using adhesives instead. While not appropriate for all applications, 3M has some incredibly strong peel-and-stick adhesive products that are proven to hold up in marine environments for over a decade. The company’s VHB (very high bond) industrial-strength, two-sided tapes have even been used for drill-free transducer mounting options.

Sacred seals

Anytime you drill a new hole, you need to use the proper sealant. For new holes, this ensures that moisture doesn’t get between the screw and the hole and either rot the wood or delaminates the fiberglass. For aluminum, using the proper sealant can not only protect any wood underneath but can serve as a barrier between the two metals, minimizing or eliminating future corrosion in the area.

A variety of marine sealants are available, each with unique strengths and weaknesses. 

A variety of marine sealants are available, each with unique strengths and weaknesses. Do your research before buying based on your specific application! Unless you specifically need a high-strength adhesive like 3M 5200, avoid it. Polysulfide and polyether sealants can damage plastics. And silicon leaves a residue after removal that can prevent almost anything else from adhering.

Covering Old Holes

So, what do you do about the holes you have inherited from previous owners and that aren’t needed anymore? There are simple and more difficult ways to address these, depending on your budget and your skill level. Here are a few options:

Seal and plate

If the area you are addressing is flat and likely to be used for future holes, fill the existing holes with the proper sealant, and cover the area with the appropriate marine-grade plastic sheeting. This protects the area that was penetrated, hides the holes, and allows for future additions without any major effort. It’s also a relatively inexpensive approach compared to fiberglass or aluminum repairs.

EVA foam decking can serve the same purpose. Old electronics holes on the top of your console, for instance, can be hidden with an EVA console topper, which also provides a grippier surface than gelcoat and a nicely dressed-up look. You can cut your own piece from bulk material or have a piece custom cut.

Accessorize it 

Rather than simply covering old holes with a flat plate, consider adding something useful. Would the hole where that old gauge came out to be a good spot for a drink holder or a glove box? Could you hide that screw hole with a handy 12V outlet for your phone charger? Could old holes in a bulkhead be covered by an EVA fish measuring stick?

Putty Up

There are several options available to simply fill in existing holes, and if you just want a simple, practical solution, there are several putty/epoxy products that are simple to mix and will permanently fill in any existing holes you have. Which putty you use will depend on the material (fiberglass, aluminum, wood) you are filling in, the size of the hole, and whether you want to tint the material to match. JB Weld is a simple solution for small holes in aluminum, but not terribly pretty.

White Marine-Tex Epoxy Putty can be tinted like gelcoat with Evercoat coloring agents. Or you can simply mix a thickening agent like Cabosil into epoxy resin for the desired consistency. In most cases, though, when you fill a hole with an epoxy putty, the repair will become more obvious over time. 

Fiberglass Repairs/Welded Repairs:

For the best and most durable solution — or if you are a little OCD about your boat — using the original material for the repair may be best, whether that is re-glassing and matching the gelcoat on a fiberglass boat or having an aluminum boat repair re-welded, but these options can be both expensive and time-consuming. Even if you do decide to go down this route, it is often better to temporarily address holes until you have enough to justify a full makeover. 

Using the original material for the repair may be best.

Eventually, every boat owner is going to have to deal with holes — whether they are drilling the first ones or dealing with those others have left. The first and best approach is to minimize holes as much as possible by using marine-grade plastics in high-demand areas. A little planning before you drill can go a long way toward minimizing the number of holes your boat will see. Ensuring that every hole is sealed properly will limit the long-term damage the penetration can do to the rest of the boat. Finally, addressing open holes properly with the appropriate materials will not only protect the boat but can greatly improve your future resale value. 

Related Products