How do you keep bugs out of your boat when it’s on the hard? Whether it’s in storage or you’re living aboard in the work yard, bug intrusion can be a major problem.
The Problem
Bugs love to enter boats through the thru-hulls. Sure, you can close some of your thru-hulls. But probably not all. And you can’t close vents for the fuel and water tanks at all.
Remember, if you’re living aboard and have a dehumidifier draining into the sink, you’ll want to keep the sink drains open. Do the same for the bilge pump thru-hulls in case of rain.
The “open to the inside” thru-hulls can let ants, roaches, bees, rodents, and even snakes into the boat. Not good.
But the thru-hulls that don’t directly open to the boat interior can also pose a problem. When we hauled out on the northern edge of the Everglades, paper wasps and mud daubers were a huge problem. Their nests would block tank vents. We saw more than one boat have to dig hardened chunks of mud or nests. One boat found their bilge pump wouldn’t work when they re-launched. When they took it apart to rebuild it, they found a mud dauber nest.The first year we stored our boat in southern Florida, we were advised to stuff screen in all the open thru-hulls and vents. It worked well. Air or water could still flow, but the bugs were blocked. However, installing screen took a long time. And Dave really scraped his hands up both while cutting the screen and when stuffing it in.
How to Keep Bugs Out of Your Boat’s Thru-Hulls
The first year we stored our boat in southern Florida, we were advised to stuff screen in all the open thru-hulls and vents. It worked well. Air or water could still flow, but the bugs were blocked. However, installing screen took a long time. And Dave really scraped his hands up both while cutting the screen and when stuffing it in.
The second year, Terry and Jenn Pierson were getting their boat ready for storage at the same time we were. I was heading into town and asked if they needed anything. Sure, they said. Stainless pot scrubbers to plug the thru-hulls. HUH? They told us exactly how they used the stainless scrubbers to keep bugs out of the thru-hulls.
It worked even better than a screen and was much easier to install. Win-win!
It works even better than screen and is much easier to do. Win-win!
Step-by-Step
- Cut each stainless scrubber into a couple of chunks (depending on the size of the scrubber and the diameter of the thru-hull) with regular scissors.
- Stuff one chunk of the scrubber into each thru-hull, keeping the outer edge flush with the hull of the boat so that bugs can’t build nests in the thru-hulls or get into the boat. You want the thru-hull to be firmly blocked off. Air and water will still seep through.
- Do all open thru-hulls and those that are closed so there won’t be any nests in the inch or two between the hull and the valve.
- Remove them all (and open any closed thru-hulls) just before putting the boat back in the water.
Cruiser’s Favorite Tips
As I said, we learned to do this from our cruising friends. Fellow boaters are a great source of tips.
Rick S. keeps a bamboo skewer available to remove spider nests from the fuel vent. Good advice, since a clog can cause your engine to fail at the worst possible time. Sherry M. relies on squishy golf ball cat toys. Squeeze to fit in the thru-hull, and they’ll expand to fill the opening. Dave T. also relies on squishy balls. He uses a spongy, Nerf-style ball in the engine exhaust.
Debbie W. adds another step that also reminds her to remove the fillers before returning the boat to the water. In her own words: “I scrunch up crinoline netting, wrap a long zip tie around it as a handle, and stuff it into the thru-hulls. The zip tie tail sticking out of the thru-hull reminds me to pull it out before we splash.”
Where to Buy Supplies
You can find stainless scrubbies in most grocery stores. Just be sure to get stainless ones, or they’ll rust out after the first rain! Don’t use green scrubbies; they are not flexible enough and will leave gaps for bugs to crawl through.
They’re a little cheaper on Amazon than at the grocery store where I bought them (everything is more expensive in South Florida), but they’re not frightfully expensive anywhere. It took two 3-packs to do our whole boat, and we had some left over.
Bill D. uses bronze wool on his boat. You can buy bronze wool at Amazon or any hardware store.
Whichever option you choose, you’ll appreciate not having to deal with bugs the next time you store your boat on the hard.
More About Avoiding Bug Infestations on Your Boat
Carolyn Shearlock has lived aboard full-time for 17 years, splitting her time between a Tayana 37 monohull and a Gemini 105 catamaran. She’s cruised over 14,000 miles, from Pacific Mexico and Central America to Florida and the Bahamas, gaining firsthand experience with the joys and challenges of life on the water.
Through The Boat Galley, Carolyn has helped thousands of people explore, prepare for, and enjoy life afloat. She shares her expertise as an instructor at Cruisers University, in leading boating publications, and through her bestselling book, The Boat Galley Cookbook. She is passionate about helping others embark on their liveaboard journey—making life on the water simpler, safer, and more enjoyable.
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