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How to Wet Sand a Boat? – 3 Steps You Should Know

Written by J. Harvey / Fact checked by S. Numbers

how to wet sand a boat

You need to know a lot of things to be able to keep a boat in good condition. Among the things that can help is understanding how to wet sand a boat. But how is it done the right way?

We’ll go over both wet sanding and buffing and look at the important details to get good results. Let’s also learn what benefits we’re looking at when considering using wet sanding. This is useful whether you have a bass boat or sailboat so let’s get started.

What You’ll Need

  • Wet sanding paper
  • Boat wet sanding kit (if using a power tool)/sanding block
  • Water
  • Liquid soap
  • Protective goggles and mask
  • Gloves

How to Wet Sand – Step by Step

wet-sanding-gelcoat

Before you start the process, you should put on your goggles, mask, and gloves. Wet-sanding can be a messy process and might contain toxic chemicals, so do not forgo your protective gear.

Step 1: Prepare the surface for sanding

The first step is to clean the boat’s surface; this is important because we want to make the sanding even. Cover any surface you won’t be working on to protect it.

Next, prepare the water; it is recommended to use soapy water. Take a bottle or bucket of water, then add a few drops of soap.

Lubricate the surface. It is important to make sure that it is wet enough. The water acts not only as a sort of lubricant but also helps clear out the materials that come off during the work process to prevent clogging.

Step 2: Sanding

wet-sanding-fiberglass

As gel coating differs between boats, there’s no definitive answer about what sandpaper grit to use. A good rule of thumb is to start from a finer one and slowly move your way up to a coarser paper. It also helps to test the sandpaper in an inconspicuous spot.

Proper wet sanding techniques with a orbital sander are important to get good results. Do not move the device in circles. Instead, work your way horizontally from one side to the other and gradually move down from top to bottom.

After one set, change your pattern going up and down vertically in the same area until the entire section has been covered a second time; repeat this process until you get the right finish.

When sanding by hand, keep your strokes long and try to rub evenly. Similar to sanding with orbital sandpaper, you should go in a back-and-forth, up-and-down motion. Moving in circles will result in an uneven job and even scratches.

Change your sandpaper regularly to keep the work efficient, and lubricate the surface frequently, as dust buildup can cause scratch marks on the boat. You’re done when you get an even and dull, matte-like finish on the surface.

Step 3: Buffing

Once the sanding is done, you may see some scratch marks on the surface. However, if the work is done properly, these lines can be taken care of using a compound and buffing. Wash and dry the sanded surface before proceeding.

Apply your polish as directed by the manufacturer of your chosen product. Buffing can be done by hand or machine but expect to take more time with this to get good results.

When using a power tool, it is important to always keep the polisher moving. Use the crosshatch patterns in step 2 for this as well. Again, you don’t want to use a circular motion here, as it’ll leave ugly swirl marks on the surface.

Reasons You Need to Wet Sand a Boat

  • Wet sanding is recommended when it comes to the restoration of a heavily oxidized gel coat on a boat. This is done by making the surface even to leave a clear finish. However, buffing is also needed.
  • Sanding is also an important step when painting a boat or when applying a new gel coat. This helps to keep the paint layer even and helps give the best result.
  • The process can help rectify a botched paint job. You can also rely on wet-sanding to eliminate the orange peel effect commonly seen on new vehicles.
  • Wet sanding boat bottom paint is recommended before applying a new coat to minimize dust. However, even when you wet sand a black boat bottom, the danger of its toxic dust remains and must still be handled with care.
  • Compared to dry sanding, wet sanding gelcoat is less abrasive and does not cut into the surface you’re working on as badly. This allows for better control and will not risk wearing down the entire thickness of the gel coat as much.

Frequently Asked Questions

What does wet sanding a boat do?

This involves sanding but with water and a different type of sandpaper. It works by stripping off a thin layer, but water prevents dust buildup that may cause further damage. It is recommended for restoring the shine of dulled surfaces such as gel coats.

What grit do you use to wet sand a boat?

600 grit can be used to start, but 1000 grit is usually more common. It’s always better to start with a lower grit and go up from there to avoid over-sanding. Start with less aggressive grit sandpaper for gelcoat and test it on a small, unnoticeable area first.

How much does it cost to wet sand a boat?

The price depends on the boat and its size, but the average cost would be around $50 to $100. If you have materials lying around or things you can use as makeshift tools, you may only need to purchase the sanding paper and it can be even cheaper.

Getting the task done by professionals can cost you even more. For every foot, expect to fork up $10-$125. In other words, the bigger your boat is, the higher the cost to wet sand it.

What product do I need to use after wet sanding?

It is recommended to use polish or wax after the sanding is done. This should be followed by buffing to make the surface as shiny as possible.

Is it necessary to wear a mask and goggles when wet sanding?

Yes, because although wet-sanding drastically reduces dust, there will still be enough of them that it is a cause for concern. You can still breathe this in, or it can get into your eyes, so protection is vital.

Make sure to protect your hands as well by wearing appropriate work gloves. Toxic chemicals can still get absorbed by your skin, so beware.

When should you sand a fiberglass boat?

While this is recommended for maintaining the shine of your boat, it is not always recommended for minor scratches. Wet sanding fiberglass is only necessary if there is significant oxidation. For many situations, applying a compound should be enough.

Conclusion

Now that you know how to wet sand a boat, take some time to practice it with care. Always begin with the least aggressive grit and go higher from there to prevent damage to your boat. It’s better to take your time than to find yourself in trouble.

Did you find this guide helpful? Try it out yourself and tell us how it went. Leave us a message in the comments section below.

Remember to boat safely.

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