5 Clever Tips to Keep Mice Out of a Boat Motor

Mice in a boat motor can be a real nightmare. Over the winter a family of mice can cause a lot of problems for your motor from corrosive urine to nibbled cables, leading to rising costs once you discover them.

Thankfully, there are some easy ways to prevent mice from getting into your boat motor and prevent damage further down the line. In this article, we’ll look at some simple tips to keep mice at bay and make sure your motor keeps working smoothly.

How to keep mice out of a boat motor:

  • Store your boat in a clean area with concrete floor
  • Make sure the cover or cowling is fitted
  • Block the intake and exhaust ports with steel wool
  • Use a strong-smelling material as a deterrent eg. mothballs or peppermint oil
  • Buy an all-natural rodent repellant

These simple solutions can be carried out quickly. It’s a few small steps that will save you a lot of time in the long run. Behind every one of these mice-repelling tips, there are some extra ideas that can add another layer of protection too. Read on for some top tips on maintaining the ultimate mice proof motor.

How to Ensure Your Motor Stays Free of Mice

If you’ve had problems with mice before, or you know other boat-owners who’ve had problems, you’ll want to take as many precautions as possible. Mice are persistent and there’s always a chance they might find a way around your defenses. Vigilance is key to avoid any mouse-related issues.

Choose a clean area to store your boat

If you’re going to be storing your boat out of the water, ideally choose a clean space to keep it. Mice like areas with lots of hiding places so they’re more likely to be found in storage facilities that are messy and unkept. You can reduce the likelihood of mice looking for a home in your motor by storing your boat in a clean, clutter free space. The best locations are free from boxes, cans and any other piles that could provide cover for mice.

If you can, a concrete floor is also better than a dirt or gravel floor. Mice can’t burrow into a concrete slab so it’s harder for them to sneak in and out. A concrete floor is also easier to sweep so it can be kept clean of leaf litter, straw, wood chippings and more. Similarly, avoid parking your boat trailer next to any shrubs or undergrowth, as this is another area that provides an attractive hiding spot for potential new inhabitants of your motor.

Make sure the cover or cowling is fitted

If you have an outboard motor, it is essential that the cover or cowling is fitted. Though the cowling should fit snugly day-to-day, if you have been winterizing your boat you may have removed it and not replaced it correctly. Any gaps left between the top and the base can be a welcome mat for mice looking for a temporary home.

Making sure that the cowling is secured properly before storing your boat is a simple step that will act as your first line of defense against mice. Take the time - 30 seconds max - to make sure it has been replaced properly.

Block the intake and exhaust ports with steel wool

Both in your home and on your boat, steel wool is by far the most effective preventative for mice. Steel wool is one of the only materials that mice and rats can’t chew through so it is the only effective barrier to stop them from coming in through any holes or pipes.

You can purchase steel wool in any hardware store or as a last resort, you can just use wire dish scourers. However, it’s better to buy a product that doesn’t contain soap. If you can’t find steel wool, use copper wiring instead. It works in a similar way and mice don’t like chewing it.

The process is very simple - simply stuff the steel wool in any holes where mice could enter your motor. Be sure to block the intake and exhaust ports, as these are favorite places for mice to get in. Any gaps or nooks you can find should be stuffed with steel wool too. If in doubt, fill it. Mice can fit through incredibly tiny spaces so it’s much better to be obsessively safe than sorry!

Use a strong-smelling material as a deterrent

Many sailors swear by using mothballs to keep unwanted mice and other critters at bay. You can keep them under the boat cover and change once or twice during the winter months.

Along with mothballs, there’s a whole range of other strong-smelling materials you can use to prevent mice from being drawn to your boat. Many people have found success using laundry fabric softener sheets, for instance. The strong smell acts as a deterrent and it’s a relatively cheap fix for a common problem. Just make sure to weigh them down to prevent them from moving or blowing away.

Other options for steering mice clear of your motor include:

  • Peppermint oil
  • Clove oil
  • Cedarwood oil
  • Pine needle spray
  • Irish Spring bar soap - I can’t help wondering if Irish Spring started this rumour to boost sales after a slow year!

How to use essential oils to prevent mice

Essential oils can be very effective and harmless mouse repellants thanks to their naturally strong smell. Mice rely on their sense of smell to navigate as they have relatively poor eyesight. Essential oils like peppermint, clove and cedarwood irritate the delicate nasal cavities of mice, overwhelming their sense of smell and make them less likely to come near.

Cedarwood is particularly potent as it contains effluvium, as well as phenols and acids that can be harmful to mice. Cedar oil may cause skin irritation and respiratory problems for rodents so they will avoid it as much as possible.

The best way to use essential oils is to soak cotton balls in the oil and leave them around the motor. You can even drop the oil directly onto the motor cover. Some sailors recommend rubbing it onto the wiring but you should do so at your own risk as essential oils may have an adverse effect on the mechanisms of your motor.

With all of these scent preventatives, you will need to change them at least once over the winter to keep them potent. To be safe, you may want to add more essential oil every week. The idea is to maintain a strong enough smell that mice and rodents are put off venturing anywhere near your boat.

Buy an all-natural rodent repellant

Alternatively, you could consider buying a purpose-made repellant. Try to choose an all-natural rodent repeller like Fresh Cab to prevent any harm coming to other animals who may find it. Fresh Cab is commonly used by farmers to prevent mice from nesting in farm machinery and there’s really no reason why it wouldn’t be effective in your boat too. The repellant comes in a pouch that you can leave next to your motor and it should prevent rodents for up to 60 days.

Extra tips to keep mice out of a boat motor

As well as the 5 key tips explained above, there are also some extra things you can do to give yourself the best possible odds in the battle between mice and (wo)men.

  1. Clear out all food, food packaging and food storage containers from your boat
  2. Remove life jackets, cushions and blankets from your boat - anything that could be used to make a nest
  3. Try to check on your boat during the winter, open up the motor and move things around to disturb anything trying to make a home
  4. Pull up any ropes, lines or ladders that can be used by mice to climb up the outside of your boat
  5. Consider getting a cat (sometimes the old ways are the best!)

How to identify if you already have mice in your boat motor

Before starting your motor up again in the spring, it’s a good idea to make sure you don’t already have mice living there. You should also check for signs of life in your motor before getting started on any preventatives. There are a number of signs you can look out for to give you a good indication whether or not you have mice.

The most obvious signs are:

  • Droppings - small, elongated pellets, usually dark in color and pointed at both ends
  • Nesting - small, ball-like structures made of shredded material like fabric, straw and cushion stuffing
  • Chewed wires
  • Built-up debris including food, nesting materials and bits of plastic

Check in any storage boxes, cupboards, compartments and in the motor itself.

If you find signs of mice, you will need to think about laying down traps or poison to get rid of the mice before they do more damage than they have already done. If you don’t see any of these signs, your boat should be clear of mice. For now. To prevent mice from moving in, follow the preventative steps outlined in this article to keep mice out of your motor.

These tips should all work to put off mice and other animals that would otherwise try to make your boat their temporary home. The best way to keep mice out of a boat motor is to practice prevention. These steps take very little time to complete and they will save you a lot of stress when spring comes around.

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