Tag Archives: Wet Sanding

Gel Coat Wet Sanding

When a boat oxidizes, it can look terrible.  But, with a little elbow grease and a long weekend, you can have it shining like brand new.  For some reason, the idea of sanding your boats finish does not sit well with a lot of boat owners.  However, if you go slow, and pay attention to what you are doing, there is little chance of doing major damage to your finish.  After all, if the finish were in good shape, you wouldn’t be thinking of wet sanding in the first place.

To get started, you need to pick up a few things, the most important of which is a high speed buffer.  I got mine at Harbor Freight for cheap, and it has worked out well.  If you watch their sale papers, you can pick one up for under $40 and many times they will have a 20% off coupon as well.  To go with that, you will need a couple of 3M pads.  One for compounding and one for polishing.  And finally, you will need a quality compound and polish.  A lot of people really like the 3M Perfect It and Final Glaze.  I was not able to find it, so I talked with a local fiberglass shop and actually purchased some from them (can’t remember off the top of my head what it was though).  After you polish up your new finish, and slap a quality marine was on it, it is also recommended to use a good polymer sealer.  Pro-Tec is generally the most widely used in this category.

Harbor Freight Buffer

 3M Compounding Pad

 3M Polishing Pad

During the whole compounding process, I didn’t take many pictures because I was so excited about getting the shine back on my boat.  Since the oxidation was not terrible, I started with 1000 grit sand paper (make sure it is designed to be used for wet sanding).  In a five gallon bucket, I put about 3 gallons of water, a few drops of dish washing soap, and my sand paper.  I also kept the hose handy.  As you are sanding, be sure to periodically dip the sand paper in the bucket to clean off any buildup and also have your hose slowly applying water to the area you are working on.  This will help you monitor the area, and once the water run off becomes clear, that is when you know you have removed the oxidation.

Since I was unsure of myself when I first started, I picked a small area on the boat and just worked on it.  After I felt like I had removed a majority of the oxidation with the 1000 grit paper, I stepped up to 1500 grit and started sanding again.  The idea with the 1500 grit is to smooth over the sanded area.  The same with stepping up to 2000 grit.  One thing to be very careful of is while you are sanding, keep feeling the area you are working on.  If you start to feel metal flake, you have sanded too far.  If you finish is oxidized all the way to the metal flake, you have a case that is too serious for wet sanding.

After you have completed the sanding, give the boat a good wash.  It will be covered in a milky white and need to be cleaned before you can begin to compound the finish.   The boat should look dull, but will be shining soon.

A word of advice before you start compounding, be sure to cover up your trim and carpet.  If you are not careful, when you hit the liquid compound with the buffer, it just may sling excess compound ALL OVER and can be a real pain to clean.  That is experience talking.

When you move on to the mechanical buffer, take it slow to start with.  You will want to keep the buffer moving and not let it stay in one place, as it just may burn through the clear coat.  After you have finished compounding, give the boat another good cleaning, and allow it to dry.  Once it is dry, switch to your polishing pad and polish, and repeat.

Once you finish with the polish, the boat should be really starting to shine.  Once you put a few good coats of wax on it, the results should impress you.

A few mistakes that I made when initially wet sanding my boat:

  • I rushed – I didn’t cover the carpet or trim on the boat.  I was so excited about compounding and polishing that I got the compound and polish all over everything.  Then, I didn’t clean it right away, so it dried.  I think it took almost a year for me to get it all cleaned up.  You can see the white specs/spray in the picture below.
  • Didn’t sand out all the oxidation – I was a little leery of the sanding initially.  Now that I am a few years out, I notice a few areas where, when the boat isn’t waxed, you can still see the oxidation.  After talking with others, I have come to the conclusion that I didn’t sand enough.
  • Buffer speed control – I thought faster was better when it came to the buffer, and there is one place I put a little bit of a swirl in the gel, and another where I went pretty much all the way through the gel and you can barely feel the flake.  They are very minor, and if you aren’t looking for the spots, you won’t see them.

Now, if you have any questions, I would HIGHLY suggest making your way to Bass Boat Central.  Some of those guys are pro’s when it comes to boat resotration, and know the in’s and out’s like the back of their hands.  In fact, here is the thread that inspired me to take on this project.