Rats! There’s a Mouse Onboard!!

By Carolyn Shearlock © 2011 • all rights reserved

Sometimes we get a VERY undesirable stowaway:  a mouse or a rat.  How do you get rid of it?  What's best?  What shouldn't you do? And what do you have to watch out for?

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

We were lucky and never had a rat or mouse aboard Que Tal.  But we had a few friends that had one come aboard.  And then yesterday, a reader contacted me for advice on ridding her boat of a “stowaway.”

So, combining what we know from friends and what Jackie told me, here are some tips.  Please add more in the comments if you can!

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.

Cat. 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:

1.  Not all cats are mousers.  Be sure to use one that is known to go after mice.

2.  To encourage it to look for the critter, don’t give it too much Cat Chow.

3.  Don’t be surprised if the cat makes a “present” of the mouse or rat carcass in an obvious place.

4.  The cat has to have 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 — and mice can wiggle through openings as small as 1/4 inch!

5.  If someone aboard has a serious cat allergy, don’t do this!

Trap. There are lots of 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 seems to be more important than the style of trap (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!).

1.  Size the trap right — a mouse trap for mice; rat trap for a rat.  One that’s too large or small won’t get the critter you’re after.

2.  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.

3.  Make sure that the bait is the only food available.  Double and triple check that all other food is in mouse- or rat-proof containers (generally metal with well-sealed lids).  Plastic bags and light-weight plastic bins are not mouse or rat proof.  If your oven has a latching door, you can store a lot of food in it that would otherwise not be in metal containers.

4.  Secure the garbage, too.  Rats and mice see it as food.

5.  For years, I’ve been told that peanut butter is much better as bait than the stereotypical cheese.  Supposedly, all mice and rats loved it!  Then yesterday Jackie 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.

6.  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!

7.  Once you’ve caught or killed the critter, handle it carefully.  Mice and rats carry a number of 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.

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:

1.  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 . . . and then sanitize the area.

This is a nasty job.  I know.  Last year, our sailing club was 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 after tearing apart a lot of wiring in his efforts to find a way out (no poison in this case).  I was the one who cleaned up the putrified 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 — and take a good shower yourself afterward.  The water you use is worth it to avoid illness.

2.  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:

1.  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 (use rubber gloves and something you can throw away to scoop them up) and 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.

2.  Throw away any 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.

3.  Replace any bins with holes. 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.

4.  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!

5.  Leave the 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.

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  1. I love your articles and have learned lots of things from your posts. What can you tell me about making toast in the galley?

  2. Well done, Carolyn. You covered it all as far as I can see, but I’m curious to see if anyone comes up with more ideas…..just in case.
    Thanks for your help.

  3. Hi Tammy! Take a look at “Making Toast Without a Toaster” — https://theboatgalley.com/toast-toaster/ — hope it helps! -Carolyn

  4. Thanks!

  5. not worried… i have a guard cat … he is lean and weighs in at a tidy 14 pounds

  6. Hmmm, not just an ounce of prevention but a whopping 14 pounds! -Carolyn

  7. Here in the Philippines it is more common for people to use sticky paper than traps – this may be true in other third world locations as well. Note that the sticky paper does not actually kill the critter. Once stuck, I fold over the paper so the critter is trapped securely inside. This prevents them from escaping if they are willing to lose a bunch of hair (they are) and provides for cleaner handling. I usually spray them first with insecticide to kill any fleas that might carry plague. Traps that kill have more problems with the fleas leaving the body as it cools and looking for their dinner elsewhere (often you). The dead critters I just dispose of over the side and let the fish dine on them; but I don’t like to throw trash into the ocean so dispose of the paper wrapped critters ashore.

    • Carolyn Shearlock says:

      Thanks for adding to the knowledge. I’ve seen the glue boards (which can be very messy) but never sticky paper.


  8. Michelle Beatty on Facebook says:


  9. I do have a warped sense of humor, don’t I?

  10. Michelle Beatty on Facebook says:

    its perfect!! Merry Christmas! !!

  11. Merry Christmas to you and everyone else!! Here, we may have a white Christmas . . . but only if you get up early enough to see the frost on the grass, no snow . . . .

  12. Michelle Beatty on Facebook says:

    if there was snow here i would be wanting snow ice cream!!! lol

  13. Good stuff which comes at *just* the right time for me!! Thanks, as always for your great information!

  14. What are my chances that two “city cats” (who wouldn’t know what to do with a mouse) would deter mice from coming aboard on the off chance that they might be mousers?…

  15. Good question — does just the presence of a cat (or maybe even a dog’s scent) tell mice to stay away? I know that if the cat is not a mouser, it won’t get rid of a mouse problem . . . but maybe it would prevent it in the first place.

  16. Jack Russell Terrier.

  17. One comment I would make about using a mouse/rat trap. DO NOT HANDLE IT otherwise your scent will be on the trap and the mouse will not go near it. Wash the trap and then bury it in any earth for a week or more or leave it, un-set tied onto the foredeck to get rid of your human scent and then only handle it with a few layers of tissue paper and for as little time as possible during baiting and laying the trap. – How do I know, I used to have a farm and we always had vermin. 😉

  18. Another tips is to simply cover mouse poison in peanut butter and then bait the surrounding area. Give it about 1-2 days and then check the bait spots, I guarantee you will no longer have that rodent problem!

  19. Felicity Critchlow says:

    Hi, Been there , done that. Tried all of your suggestions as well as sticky pads and an electronic trap. Our circus rats just went over, or around. Common theory in the Virgin Islands was peanut butter or carrots said a pest control pro. Fed on the garbage. Finally found a nest with 4 babies. We then emptied the garbage and filled it with poison pellets. The good news is this worked but it isn’t instant. They took the poison to spots all over the boat. We were fortunate to catch one staggering across the cabin sole and another in the electronic trap. All in all 6 rats took 6 weeks to get rid of. I was seriously thinking of sinking the boat and going home.
    All of the cleanup advice is great but not only do you have to check wiring, we had to change all of our fresh water hoses, replace all polypro line, replace many vaccuum bags with linens and clothing, disinfect the bilge, the list goes on.

  20. We had a Mallard lay four eggs in a cubby in the cockpit last month. Last year a mud dauber made a nest between hull and back of a locker.

  21. Schipperke dogs were bred to keep rats and mice off of barges and sailing ships. And most rescue people are thrilled to adopt out a schipperke or schipperke mix to a liveaboard/cruising boat. They know the dog will be happy!

  22. We had swallows nest in our boom a few years ago. Too soft to get rid of them.

  23. Carolyn, we just had an uninvited rodent on Totem for four weeks. Your post was like a checklist and I think we tried just about everything here! If there’s one thing I learned it’s that the preferred bait varies by locale. People swear by the only thing that works, and it probably works for rats where they are- but not necessarily where you are. We tried a number of different selections but it was local knowledge that won. Ultimately, a live trap with toast+jam did the trick here in Malaysia.

    I’ve got one other idea for you to add, something unexpected that turned out to be useful in more than one way. Guess what? “There’s an app for that”! Ultrasonic frequencies are irritating to rats. We could sometimes find 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 I think it’s worth adding to the arsenal of options to try. Here’s the one we used: https://itunes.apple.com/au/app/ultrasonic-repeller/id445318668?mt=8

    …may you never need it…. 🙂

    Our experience: http://www.sailingtotem.com/2014/08/oh-rats-getting-rid-of-rodents-aboard.html

    • Toast & Jam? Never would have guessed that! And had no idea there’s an app for ultrasonic frequencies . . . now I’ll just have to see if there’s one for Android, too. I’ll bet there is. And I’m really, really hoping that no rodents took up residence on Barefoot Gal while she was stored over the summer.

  24. OH, and one other thing to add, re: comments above! Although multiple boats have acquired rats in this marina during our stay, NONE of the boats with cats have had a rat problem. It could be chance, I suspect those boats are wisely avoided by the super smart rats.

  25. to PREVENT rats coming on board in marina’s in Malaysia, we’re going to put 1 meter pieces of PVC pipe on every landline … wider than the line, but not TOO wide, otherwise they crawl through the pipe 😀 …

    • No harm in trying everything, but I don’t think this will help you much. The rats are acrobats for more than tightrope walking: they’ll jump from the dock to your boat, and they are more likely to get on that way than along your docklines anyway.

  26. Exterminator told us to put Slim Jim’s in the rat traps on board & it worked! It’s been our “go-to” with the last 3 rat infestations & gets those pesky critters within 24 hours. We were trying poison, peanut butter, sticky mats, everything. No luck. Rats! UGH!!!!!

  27. Smoke them out ive seen this used in a wood shed with a old metal pan with sand In the bottom and smouldering rags and bits of damp wood . He thought he had one mouse but they came flying out of everywhere . Then you will have to vent the boat for a whyle but it should work the same will be rodent free .

  28. Hugh Moore says:

    We bought a Boa Constrictor from a local pet store and let it loose on Wild Goose. After a few days, when the mice were gone, we sold the Boa on Craigslist because we didn’t want to have to keep it fed at sea. The hit we took in selling the snake was less than the cost of a few mouse traps.I hope this idea is helpful to other cruisers.

  29. Gene Goodman says:

    A few years ago we acquired a rat in the St Johns River; tried peanut butter in a regular trap. Believe it or not the rat ate the peanut butter without getting wacked. Out of desperation called an exterminator that sold me a “marinized trap” In essence a regular rat trap that you see around restaurants and marinas only this had a brick in it. The key however was his advise to use bacon as a bait. That evening we got him and ended the trauma. One extra fact this trap had a much faster and stronger spring that made quick work of the critter

  30. This summer we were on a friends boat for a weekend and actually had a raccoon fall through a hatch at 2:30 in the morning. Little tougher to get rid of than a mouse!

  31. Locals here (PNW) LOVE Avocado, especially the pits!

  32. cat !!!

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