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How to Wet Sand Your Boat? Follow these 5 Steps!

Updated: Dec 27, 2022



Wet sand your boat? This debate among detailers seems to go back and forth! Is it worth it or not?! Over my 3 years of detailing I've noticed a significant difference in the finish of a boat and the longevity when you sand oxidation rather than trying to buff it out. As I always say, if you tune in to my YouTube channel (Simon Kromer), buffing is for removing scratches and defects. Sanding is for removing oxidation. And on that note, today we are going to talk about the advantages of sanding your boat. Stick around until the end, because maybe you are the boat owner that needs a wet sand 😳 Let's find out!


Wet sanding can seem pretty intimidating, and look, I completely understand. I can still remember the first boat I sanded in my career, a 27ft sailboat in Sandusky, OH that had been baking in the sun for 20 years. As much time as I wasted on that boat to figure out wet sanding, I had taken away many lessons. Oh and I couldn't imagine if I had tried to buff that, it would have barley took a layer of oxidation off that boat! The process for that boat was 400, 600, 800, 1000, and 2,000 grit. Followed by buffing, polishing, and a coat of wax at the time which was Collinite. And you probably know my opinion on wax nowadays haha. If not, check out our other blog posts! I was just thinking, I probably have a picture of this sailboat after completion! Check it out below!



Most boats aren't going to require this extreme of a process. As a boat owner, assess your boat quarterly and make sure you're doing the necessary buffing and polishing before your oxidation gets out of hand. Because you only get two chances at wet sanding your boat until you compromise the gel coat. Wash your boat regularly with a PH balanced soap (every 2 weeks), Apply a polymer sealant every six months, or a ceramic coating every 12-18 months, and avoid harsh chemicals and degreasers on your gelcoat. Examples: Dish soap, acids, bathroom cleaners, toilet bowl cleaner, 😳 and bleach! Alright, I think you get the point. Now for the fun part! How to know when you need to wet sand?


The first step to considering the level of oxidation on your boat is to give your boat a good wash, and this is the ONLY time it's okay to use dish soap. Dish soap is only good on boats for stripping wax and cleaning surfaces directly before detailing. It also helps to remove oxidation. After you have washed your boat thoroughly, you can now access the level of oxidation on your boat. Sometimes, what appears to be oxidation is actually just dirt and particles that have built up on the surface of the gelcoat. Usually this holds true for boats 5 years or newer. So keep this in mind, what is the year of your boat? Newer boats typically don't have oxidation for a few years. Boats 5 years or older, usually have oxidation without proper maintenance. If you have an eye for detailing, perhaps this will be the only step you need to make the decision for sanding or buffing your boat. If not, let's assume most boaters don't, here's what to look for! After washing, look at the boat, and see what the shine looks like. Can you see a shine? If not, that suggests sanding. It's okay if you are still unsure at this point! Let's continue, we have more steps to help you.



The second step for considering oxidation, after washing your boat of course, is to rub you hand across the surface of the gel coat that you are examining. Does a white, powdery dust come off your boat and onto your hand? If so, this is almost always (99%) a clear indicator of wet sanding. I used to use this strategy in the past to help me make clearer, more educated decisions for my clients. Between the first two steps, and considering I had a great eye for detailing, I was able to determine grits and steps with a vision in my mind how the boat would turn out. Look, I get it, if you are new to sanding, perhaps you are still confused about what to do. And we haven't even talked about determining grits. Don't worry, we will get there! Let's continue to step three because we still need better ways, more accurate ways for determining oxidation because it's probably not as straight forward as I make it seem. Stay with me!



Step three for considering oxidation is to take a flash light, your phone flashlight will work, and put it directly up to the gelcoat. What level of clarity is there? Can you see the light clearly? Do you see scratches? Is the image through the light a little cloudy? Or can you not see the light at all! Well, fortunately 2 of these questions refer to wet sanding and 2 don't! Can you guess the 2 for each? I'll give you a minute... Okay so the two that don't suggest sanding are the first two questions and the 2 that refer to sanding and the last 2 questions. Remember, scratches don't mean sanding, because buffing removes scratches, that's why compounds come in grits. So you can select the correct grit for removing scratches and shining up the gelcoat. Now the last two questions propose a different strategy. "Cloudiness" the term I'm using for oxidation refers to wet sanding. Wet sanding will cut through oxidation. You can't just buff an oxidized boat and expect to remove all the oxidation effectively. Often times when you do this, you will be buffing oxidation around the boat. We want to remove it, not cover it up with oils from the compound/polish.



So you probably feel pretty good right? I'm sure these 3 steps have helped tremendously, but hang on, we still have 2 steps left 😳 When I'm finished with this blog, my goals is for any boat owner or detailer to be able to implement this on their boat / client's boat TODAY! Step number four requires an investment into a tool. Tools are our friend during detailing. What's that tool you may ask? It's a gloss meter! A gloss meter will directly read the level of gloss on your boat. After using the gloss meter on a number of oxidized boats, I have determined a reading that is pretty accurate for suggesting wet sanding. I'll share the link to the gloss meter at the end of the blog, where you can purchase if you desire. That reading on this meter, the one I have in particular, although all meters should be relatively the same is a 50. If your gloss meter reads a 50 or lower this suggest light sanding near a 50 reading all the down to heavy sanding at a 10 or below! These tips just keep getting better and better, but wait! One more tip below. Continue reading because we have more to cover before you are ready!



The last and final tip is... to run a test spot! Running a test spot is the only direct way to know what kind of finish you want and desire for your boat. A test spot and then a gloss meter reading is ideal, but if you have a good eye for detailing, I suppose that's efficient :) After a test spot and a reading between 90-100 on the gloss meter, you are sufficient in your detailing efforts. Ideally 95 for those of you who want higher standards haha (like me). Now you have all the tools and after considering all the steps I mentioned, run a test spot. Tape off a section of the boat so you can clearly see the results compared to the rest of the boat. If you think you can reach a high gloss with buffing, try it! If you have read through these steps and think you definitely need wet sanding, try a light sand. A light sand is 1,000 & 2,000. If you think you need a moderate sand go for 500, 1,o00, and 2,000. And for a heavy sand this may consist of what I did on that sailboat above (400, 600, 800, 1000, and 2000).



I only felt like it was right to add on more section in this blog and that proposes a question. How do you know when to stop sanding? During the sanding process, keep a hose nearby. Every time you sand a section, rinse off with water. If the water turns white, you are removing oxidation through your efforts. Once that water becomes a light white to almost clear, you have now fully removed the oxidation. At that point work up the sanding grits until you hit 2000. If you time this correctly, you will have this result, the light white to clear water on the final step of sanding! This ensures you are removing mostly oxidation and as little gelcoat as possible. This is the desired goal through your sanding efforts because when you are removing gelcoat you shorten the lifespan, which should sound familiar :). Unfortunately, I can't teach this step of actually doing, but I gave you the tips for success. Now, you have to go out and do it for yourself!


  1. Wash your boat

  2. Rub your hand across the gelcoat

  3. Use a flashlight

  4. Gloss meter reading

  5. Run a test spot


Owning a boat is a lot of work, a time commitment, and sometimes involves work you are unfamiliar with. Top Dock Pro specializes in boat restoration in Cape Coral, FL. After reading the blog, if this process seems over your head or you would rather spend your valuable time elsewhere, we can service all your detailing if you are a local! Go to our homepage and fill out a quote that will be directly sent to our team. Thanks for reading and supporting our page. Happy boating!



To learn more about boat cleaning and detailing tips follow us on YouTube. Want to keep up on our day-to-day projects? Or maybe learn a quick tip? You can do so by following us on our other social media platforms listed below. If you have a comment for this blog, drop it below, we want to hear from you. Until next time!



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