Does Rain Really Damage a Boat?

Boats can be important investments, especially if you plan on taking them out on the water frequently or the boat is required for your job. However, to ensure your vessel functions well for years to come, it is crucial to keep it protected from the elements, like rain. This leads to the question, does rain really damage a boat? How do we know?

Does Rain Really Damage a Boat?

Can rain really damage a boat? Leaving a vessel exposed to environmental conditions—such as rain, sleet, and snow—can lead to long-term damage, especially to its interior and engine. For this reason, it is highly recommended to cover your boat when it is not in use.

Although boats spend plenty of time in the water, exposure to the elements—even rain—can cause damage to your vessel. This article will discuss how precipitation can affect your boat’s longevity and how you can prevent it.

Effects of Rain on Boats

It can be hard to imagine rain hurting something that is designed to be in the water regularly, but there are a couple of ways that precipitation can hurt boats.

Uncovered boats can catch plenty of water from rainfall—like a large bowl. The standing water can lead to gradual damage to the vessel’s interior, especially if the water remains undrained for long periods. Types of damage you may find include:

Does Rain Really Damage a Boat?


Most fiberglass boats have wood and foam materials encapsulated within the hard fiberglass shell. If water seeps inside the vessel’s hull fittings, transom, or driveshaft seals, it can lead to mildew and mold development and rotting.

Rotting will eventually break down these critical structures and make your boat less stable for taking out on the water. The effect is more detrimental if you have a traditional wooden boat. Also, rotting can be difficult to see since it usually occurs in these hard to reach places. Many times, the rotting parts of your boat are found far too late to reverse the damage.

If you suspect water may have gotten inside of the boat, make sure that the interior is completely drained and dried as soon as possible.

Engine Damage

Often, the lowest part of the hull is the home for a boat’s in-board engine. If standing water ends up inside the hull, the engine can easily accrue damage that can become quite costly to fix.

Protecting Boats from Rain

It is essential to keep your boat covered while in storage—no matter the time of year—to protect it from rain. Ideally, you should have a well-fitting boat cover that can stop or reduce the amount of water that can accumulate inside the vessel.

Does Rain Really Damage a Boat?

Types of Boat Covers

West Marine explains the different types of boat covers that you can choose from:


Shrink-wrap can effectively block rain—as well as debris—from entering your boat’s interior. However, shrink-wrap can also retain moisture which can lead to condensation and eventually mold in warmer conditions.

You must make sure that your boat is completely dry inside and out to effectively use shrink-wrap as a cover. You could also add vents as you install the wrapping to allow any remaining hidden moisture to escape.

Another disadvantage of shrink-wrap is that it can only be used once; after it has been removed from the boat, you will need to purchase more shrink-wrap to cover it at the end of the boating season again.


Polyethylene tarps are the most common type of tarps for covering boats. These tarps work quite well for preventing rain from entering the vessel. However, you will need to strap them down to keep them from flying off the boat as a result of wind and exposing it to moisture.

One way to secure tarps in place is by creating an A-frame support system out of standard 2x4s and horse brackets. The frame is then placed inside the boat, and the tarp is stretched over it and strapped down tight. (Note: This method only works for certain boat configurations.)

Fabric Covers

Fabric covers allow more airflow, so when it is time to take your boat out of storage, you are less likely to experience a lingering smell of mildew. Fabric boat covers are also easy to remove so you can access your vessel at any time.

There are several types of fabrics to choose from when it comes to picking a fabric boat cover. The ideal cover should be able to breathe, repel water (and allow trapped water to escape), and remain UV and mildew-resistant. Also, the fabric should have a high enough tensile strength and abrasion resistance to avoid being affected by severe storms.

The most common type of fabric that combines most of these needed features is coated synthetic material, although other fabrics offer other advantages:

  • Cotton and polyester blends – These fabrics can breathe more, but may not last as long as synthetic fabric since they cannot stand against mildew and UV light.
  • Pigment dyed polyester – These fabrics are sturdy and breathable, can repel water, and hold under constant UV radiation exposure.
  • Acrylic coated polyester – This fabric is another good option and is often chosen for its affordability. It is an excellent material to pair with traditional wooden boats, as long as you install vents.
  • Urethane coated, solution-dyed polyester – This material is breathable, and stain-, UV-, and mildew-resistant. It can also repel water very well.
  • Solution-dyed acrylics – Similar to urethane coated, solution-dyed polyester, this fabric can breathe well and is resistant to stains, UV rays, and mildew. It also repels water.

Custom Covers

Although these boat covers are typically more expensive, they eventually pay for themselves when you consider the amount of damage they protect your boat from—especially from environmental factors such as rain and snow and other debris that can fall into the boat hull and lead to damage that requires costly repairs.

Custom covers can also be more affordable over time compared to purchasing shrink-wrap every year.

Other Tips for Protecting Boats from Water Damage

  • Make sure that your boat is completely drained of water before covering it. Remove the hull drain plug and make sure that all of the draining passages are free of any debris.
  • If you plan on storing your boat in the water, check that the operating battery is fully charged and that the automatic bilge pump is operational—this will ensure that the pump can remove any water that happens to enter the bilge while in storage.
    • Also, if you happen to bring your boat to the lake or sea and experience heavy rainfall while you are out, an automatic bilge pump will ensure that water is sent out as quickly as it comes in.
Does Rain Really Damage a Boat?


Even if your seafaring vessel is in the water for most of its lifetime, you can still see potential damage from environmental conditions such as rain. Rain does not only cause exterior damage to your boat’s hull, but it can also affect its engine and other vital components that help it function.

To protect your vessel and prevent long-term damage, it is highly recommended to keep it covered with a well-fitted boat slip or cover. A cover will help stop or reduce the amount of rain that can enter the boat’s interior and lead to irreversible harm. Doing this allows you to spend more time doing the things you love on the water and less time worrying about the costs of extensive repairs.

Does Rain Really Damage a Boat?