How to Clean The Bottom of a Boat (7 Quick and Easy Ways)

How to Clean The Bottom of a Boat (7 Quick and Easy Ways)

While it is all fun and games hitting the seas, you should also not forget to maintain your boat from time to time. From my experience, most boat owners concentrate on cleaning the upper areas of the boat and the boat hull because those areas are the easiest to clean.

However, I believe that the area that needs a lot of maintenance is the bottom of the boat. It’s for that reason that I’m dedicating this entire guide just to teach you how to clean the bottom of your boat.

Why the bottom of the boat? Think about it– it’s the area that’s submerged in water all the time. If you don’t clean it, it’s going to wear out real quick.

Of course, cleaning it won’t be a complete walk in the park. That’s why I’ve listed my top 7 tips on boat bottom cleaning so you can get the job done as quickly and as effectively as possible.

So let’s get to it then!

Clean The Bottom of a Boat

1. Clean Your Boat Based on Material

There are many boats made out of many different materials. The common ones are copper/steel, wood, and fiberglass. Because of the nature of these materials, the cleaning method that you should use on all of them should be different.

For copper or steel boats, you can just use a pressure washer to wash them. However, do take note that a pressure washer can’t take out the growth completely. You can manually scrape out the growth and take out the remaining with the pressure washer.

Generally, you don’t need to use chemicals but if the growth is dry and is stuck to the material, you’ll need to use some chemicals.

For wooden boats, you need to be careful when using a pressure washer because the strength can destroy the boat. Use only weak to moderate pressure when cleaning wooden boats and don’t wash for too long. Scrape as much as you can and end with the pressure washer.

Lastly, let’s look at fiberglass bottomed boats. As a general rule, I think that fiberglass bottomed boats have to be scrapped as soon as you bring them out of the water. You need to scrape out as much as you can because high pressure can also damage fiberglass material.

From my experience, I always make sure that fresh growth will be taken out right away. Then I can pressure wash the fiberglass bottom just a bit.

2. Regularly Scrub the Barnacles

wax the boat

I know that you can’t exactly bring the boat out of the water all the time, especially if it’s a big boat. You can try but it’s going to be extra work for you. So what I recommend is that you scrub the barnacles off underwater.

Just buy a scuba kit and get a sponge or a light-duty 3M pad. You can do this every couple of weeks so that the barnacles don’t get stuck there. I always believe that prevention is better than cure. Don’t wait for the barnacles to build up because they’ll be harder to take out if they do.

3. Don’t Scrub Off Paint Underwater

Let’s say you left your boat unmaintained for a couple of weeks and a lot of marine life built up under the boat. Of course, your first instinct may be to go underwater and start cleaning them up. However, I don’t recommend that you do this.


For one, it’s bad for the environment. Once you scrub off a lot of barnacles or marine life, there’s a huge chance that you’ll scrub off the paint as well– paint that you’ll be releasing on to the sea. Aside from being a big boat enthusiast, I’m also a pretty hardcore environmentalist. As much as possible, I don’t want to do anything that may hurt the environment in any way.

Secondly, there are regulations on releasing chemicals to the sea. There are local laws that specifically state that underwater boat cleaning is not allowed.

Granted there are some areas wherein underwater cleaning is allowed, you should still be a responsible citizen and take care of the environment when doing this.

So for this kind of situation, I recommend that you bring the boat out of the water, take out the marine life in the open air, and repaint the boat.

4. Use a Putty Knife to Scrape Out Barnacles

Depending on how tough the marine life stuck to your boat is, a sponge or a 3M pad may not cut it anymore. In these cases, I found that a putty knife works well in taking out these marine lives. Using a putty knife to scrape them off may take more time and energy, but they are more effective than using a sponge.

5. Don’t Forget the Waterline

As part of cleaning the boat’s bottom, you must pay extra attention to the waterline. What is the waterline, anyway? In simple terms, it’s the line where the hull of the boat touches the surface of the water. Why is this part so important, anyway? Well, it’s usually the place where the weeds and the slime stick.

I always find this place to have the thickest slime coatings on the entire boat bottom. That’s why I make sure to scrub this area thoroughly. If the slime, weeds, and barnacles build up too much, I even take the boat out of the water to clean it.

I understand that taking the boat out of the water requires a little more work and help than usual. Although I’d say it’s worth it if you can have your boat sparkling clean afterward.

6. Follow this Rinsing Process

This is the cleaning process that I usually follow when I bring the boat out of the water to clean. First, I do the initial rinse with my pressure washer. This is to ensure that I take out as much salt, algae, and marine life as possible. I usually just do one round of rinsing for this stage.

Next, I do the scrubbing. This is where things will get a little tricky. As I mentioned, you need to scrape or scrub the boat based on the material of the boat. You can refer back to tip 1 to know the details. You can also use boat cleaners if you need to.

The last step is to do a final rinse. This will take out all the remaining debris or marine life on the boat. So just to sum it up, the process goes like this:

Rinse- Scrub- Rinse.

If you find that there is still some debris or marine life stuck to the boat. Just repeat the process.

7. Wax the Boat

My final tip to keep your boat sparkly and clean is to wax it. After you’ve brought your boat to the surface and gave it a good clean, wax it so it looks fresh. Now, waxing isn’t just an aesthetic type of thing. It also prevents damage from UV rays, protects the boat’s design from wearing off, and prevents marine life from sticking to the boat.

To wax your boat, all you need to do is to get an old cloth or a power buffer. I recommend that you buy a power buffer if you have a medium-sized or a large-sized boat. These buffers work extremely well in giving your boat bottom that extra shine.

I also recommend that you buy either LifeWax or GraphicWax. GraphicWax is especially useful if you have a very colorful boat design and you don’t want it coming off. GraphicWax’s formulation somehow helps maintain the design even after long use. If not, then LifeWax will do.

After you’ve applied the wax and buffered it, let the wax set before you bring it back into the water. Maybe wait a day or 2 just to be safe. I usually let my boat set for 2 to 3 days before I bring it back to the harbor.


And that, my friends, are seven of my best tips on how to clean the bottom of your boat. Now, if you don’t want to maintain your boat, you can hire someone to do it for you. There are even some cleaners that are trained to clean the boat underwater.

However, I believe that one of the joys of having a boat is also maintaining it. Seeing it in its prime is something that a boat owner can always be proud of, especially if they maintained it by themselves.

If you share the same sentiments, then these 7 tips will greatly help you.

I hope you have a good day!

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