Getting Rid of Rodents on Your Boat

No one wants to have a mouse or rat on their boat. Besides carrying disease, they get into food stores, nest in cushions and mattresses, and even eat insulation off wires, creating a fire hazard.

We were lucky and never had a rat or mouse aboard Que Tal. But a few friends had one come aboard. Here’s combined wisdom based on our experience, our friends, and fellow cruisers.

Getting Rid of Rats and Mice

If you’ve got a critter on board, there are basically three ways to get rid of them:  (1) a cat; (2) a trap; or (3) poison.

Cats

If another boat in the anchorage or marina has a cat that’s a known “mouser,” see if you can borrow it for a few days.

A few words of wisdom on this:

• Not all cats are mousers.  Be sure to use one that is known to go after mice.
• To encourage it to look for the critter, don’t give it too much Cat Chow.
• Don’t be surprised if the cat makes a “present” of the mouse or rat carcass in an obvious place.
• Give the cat access to the entire boat. Don’t close off lockers, the lazarette, the bilge, or “rooms.”  The mouse will try to find a place that it can go but the cat can’t. Remember, mice can wiggle through openings as small as 1/4 inch!
• If someone aboard has a serious cat allergy, don’t do this!

Traps

You’ll find many different styles of mouse and rat traps, all claiming to be the best. The reality is that you’re stuck with what you can get your hands on quickly. And the bait you use is probably more important than the type of trap (more on bait below).

Yes, some traps make it less messy to get rid of the critter once it’s caught/dead, but you’re a cruiser and can handle it!. Here’s what you need to know about traps.

• Size the trap right: use a mouse trap for mice; a rat trap for a rat. One that’s too large or small won’t get the critter you’re after.
• If you decide to use (or can only get) a “humane” trap (one that doesn’t kill the critter), think about where you’ll release it. It had better be far, far away.
• Make sure that the bait is the only food available. Double-check that all other food is in mouse- or rat-proof containers (generally metal with well-sealed lids). Plastic bags and lightweight plastic bins are not mouse- or rat-proof. If your oven has a latching door, you can store a lot of food in it.
• Secure the garbage, too. Rats and mice see it as food.
• Place traps near the food they’ve been getting to, or in places where you’ve seen the mice or rats. You want them to find it!
• Once you’ve caught or killed the critter, handle it carefully. Mice and rats carry diseases that you really don’t want to get, including bubonic plague and salmonella. Spray it with a strong bleach solution, double-bag it, and dispose of it where kids and pets won’t accidentally get into the package.

While cruising in the Philippines, Bruce used paper sticky traps (more common in less developed countries). To contain a rodent once caught, he folds the paper over the critter to prevent it from escaping if they are willing to lose a bunch of hair (they are). It also provides for cleaner handling. He also sprayed them first with insecticide to kill any fleas that might carry plague. He warns that traps that kill have more problems with the fleas leaving the body as it cools and looking for their dinner elsewhere (often you).

All About Bait

For years, I was told that peanut butter is much better as bait than the stereotypical cheese. Supposedly, all mice and rats loved it! But that wasn’t the case for my friend Jackie. She reported that cruisers in the Rio Dulce, Guatemala, told her that mice there didn’t like peanut butter. She used a bit of her “good cheese” and caught the mouse in less than a day. If one bait doesn’t get results in 24 hours, I’d suggest switching. And check what the locals recommend.

My friend Behan on s/v Totem reported that toast and jam helped her catch her stowaway in Malaysia. Locals advised her to try it, and it worked.

Reader Kim said that after every other bait failed, they succeeded with Slim Jims! The recommendation came from a local exterminator. Gene was advised to try bacon in northern Florida, which did the trick. 

Poison

Yes, you can use products like D-Con or locally available poisons. I urge you to try the other options first, for two reasons:

The Problem with Dead Rodents On a Boat

A poisoned mouse or rat isn’t going to leave the boat to die. They are going to find some inaccessible corner and lie down. In time, they will begin to decompose.  The boat will stink, and you’ll have to play “find the stinky critter” and extract it from where it was. Then sanitize the area. This is a nasty job. I know. 

Our sailing club had been given a pontoon boat to use as a race committee boat at a very good price. The catch was that a possum had come aboard during the winter and died in the steering pedestal. Trying to find a way out, he tore apart a lot of wiring in his efforts to find a way out (no poison in this case). I cleaned up the putrefied possum, the surrounding area, and the wiring, then fixed the wiring. Trust me, it’s not something you want to do. But it has to be done.

Should you ever have to clean up something like this, use rubber gloves, paper towels or rags that you can throw away (immediately after finishing the job), and a strong bleach solution. Take a good shower yourself afterward. The water you use is worth it to avoid illness.

Poison Endangers More Than Just Rats and Mice

If you have kids or pets aboard, it’s just not safe to use poison. And with the motion of the boat, even at anchor, it’s easy to get poison in places you never intended.  This is another reason I just don’t like poison.

After You’ve Gotten Rid of the Critter

Once the critter is disposed of, you need to do several things:

Clean Up Droppings

Okay, you probably did this as soon as you found them. But now you need to go on a whole-boat scavenger hunt. Sweep up any that you find. Wear rubber gloves and something you can throw away to scoop them up. Use bleach spray (make it twice as strong as you would otherwise) on the area after you’ve picked them up.  Mouse and rat droppings are very likely to carry Salmonella, a potentially very serious food poisoning.

The New York State Department of Health recommends NOT vacuuming droppings as it can put possibly harmful dust in the air. They recommend spraying first with the bleach solution, then sweeping into a plastic bag and double-sealing it.

Throw Away Food They’ve Gotten Into

You don’t want any diseases they could be carrying. And if you’re lamenting the cost of your provisions, just think about the hospital and doctor bills — and possible evacuation to better medical facilities. The food is cheap in comparison.

Replace Damaged Bins

Yeah, the critters are likely to have put holes in one or more of your food storage bins. And with a hole in it, it won’t protect your food from other critters such as bugs or from dampness and humidity. Make a list and replace them when possible.

Check Wiring

Carefully inspect all wiring on the boat to see if insulation has been chewed off. If so, you’ll have to repair or replace it. Pay particular attention to wiring in and near lockers with food and any others that have droppings in them.

Don’t skip this step. You do NOT want a fire aboard!

After six weeks tracking onboard rats, Felicity had to change all fresh water hoses, replace all polypro line, replace many vacuum bags filled with linens and clothing, disinfect the bilge, and more.

Leave Trap(s) Out For a Few Days

Just because you’ve trapped one critter, don’t assume it’s the only one aboard.  Keep the traps out for a few days in case there’s more than one.

Dealing with the problem sooner rather than later is best. If you wait, there’s always a chance of babies and the problem multiplying. Problems, no matter how nasty, don’t go away by themselves. You really have to take not only swift action, but complete action to rid the boat of the critter and any consequences of it having been aboard.

Other Cruiser’s Tips

Cruisers from a variety of locations have their own tips. Here are a few you might consider.

Animals Other Than Cats

Besides cats, other pets might be able to get rid of rodents. Some dogs, particularly terriers, are bred to track and kill rodents. Diane E. recommends Schipperkes, a Dutch breed developed to keep rats and mice off barges and sailing ships. I loved having our wonderful boat dog, Paz, aboard. But dogs complicate cruising. Wanting to keep ahead of rodents is a poor reason to get one. But if you’ve considered adopting a cruising dog, this is one more reason to consider one.

Our online course, Cruising With Your Dog, shares all the details of living aboard with a dog, beginning with adopting the right one, preparing them for boat life, and the realities of cruising with one.

Do you have a taste for more exotic animals than dogs or cats? Cruiser Hugh bought a boat constructor from a local pet store to rid their boat of rodents. Within a few days, the boa was well fed, and his boat was mouse-free. He sold the snake before setting off again.

Other Traps

I have no personal experience with this method, but a reader sent it to me with a picture, so I’ll share their method here. “Last week I read about a 5-gal bucket mouse trap that drowns mice or rats. I recently lost my straw cleaning brush, so while I was looking on Amazon, I found a 13 pc. stainless steel straw and brush set that included a large milkshake/smoothie straw.

With cooler temps in Southwest Florida, I began noticing droppings in the cockpit.

Instead of using a large 5-gal bucket, I used the smaller 2-1/2 or 3-gal bucket, and I was able to use one of the long smaller diameter straws as the rotary base for the large diameter milk shake straw and capped the outside ends of the smaller straw with the silicone mouth protectors on both ends.

No need to build a “ladder” for the critters to climb up the bucket. Just set the bucket in the cockpit sole against the seats and let the little or big shits fall in the water and drown.”

Finally, Behan shared her method of flushing out her rat: an app. According to Behan, ultrasonic frequencies are irritating to rats. They sometimes found the rat’s location on the boat during daylight hours by having the app on nearby: it would scuffle around to get away from the sound. I know from past experience that this works (at different frequencies) for mosquitoes, too. It won’t work for every boater (need device + no power issues) but, it may be worth adding to the arsenal of options to try. You can find the rat repeller app she used on the Apple App Store.

There are several options for rat repellers available for Android devices. Make sure you choose one with a frequency that’s effective for deterring mosquitoes as well. You’ll have plenty of chances to use it when you’ve gotten rid of the rodents.

Prevention is Best

Anything you can do to keep rodents from boarding your boat is best, especially when you’re leaving the boat on the hard. My tip for keeping bugs out of thru-hulls also works for rodents. And speaking of leaving the boat, here’s a good list to help you prepare your vessel so it doesn’t attract critters while you’re gone.

Hopefully, you’ll never have to deal with rodents on your boat. But if you do, these tips should help you eliminate them.

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