Sand/polish metal flake gelcoat?

[Gdmatson 25]

I used a Harbor Freight cheapy on a 36 foot SeaRay I owned. It does have variable speed and worked great. I typically buy the best tools, but in this case, it’s a tool that would only get used once in a great while. The boat was badly oxidized and I used a strong automotive cutting compound that I can’t seem to find the name of. For light scratches, I used 3M Finesse It, which did a great job! I have always used 3M or Collinite paste wax twice a year. Hope something in there can help.

[InfinitySurf 302]

My boat turned out awesome with compound, polish n wax (some wet sanding was needed in couple areas). Took pic last night with boat and trailer waxed....and then a close up pic showing gelcoat around vent (should have gotten some others), but really happy considering it was my first time doing it to entire boat.

Just need to finish interior polish to gelcoat sometime soon, it just needs a polish and wax to pop.

[namadio 0]

On 4/19/2018 at 11:41 AM, InfinitySurf said:

My boat turned out awesome with compound, polish n wax (some wet sanding was needed in couple areas). Took pic last night with boat and trailer waxed....and then a close up pic showing gelcoat around vent (should have gotten some others), but really happy considering it was my first time doing it to entire boat.

Just need to finish interior polish to gelcoat sometime soon, it just needs a polish and wax to pop.

Your boat turned out amazing!  Would you mind providing some details on your wetsanding process?  When I was younger I worked at a marina and did some buffing with compound/polish and very very minor wetsand.  My centurion is a 2002 and has serious oxidation requiring a full wet sand.  I tried to do the entire transom to start with after testing a small spot at bottom of the transom.  I used 1000 grit, 1500, then 2000 with a little soap in the water.  Then buffed with a compound said to get out 1000 grit scratches.  The small test spot looked great, the transom shined up to a degree but the sanding scratches never completely came out.  And even with polish then wax, it was completely oxidized again within a season or 2.  I never finished the full boat but need it so bad now.

What am I doing wrong?

[InfinitySurf 302]

14 hours ago, namadio said:

Your boat turned out amazing!  Would you mind providing some details on your wetsanding process?  When I was younger I worked at a marina and did some buffing with compound/polish and very very minor wetsand.  My centurion is a 2002 and has serious oxidation requiring a full wet sand.  I tried to do the entire transom to start with after testing a small spot at bottom of the transom.  I used 1000 grit, 1500, then 2000 with a little soap in the water.  Then buffed with a compound said to get out 1000 grit scratches.  The small test spot looked great, the transom shined up to a degree but the sanding scratches never completely came out.  And even with polish then wax, it was completely oxidized again within a season or 2.  I never finished the full boat but need it so bad now.

What am I doing wrong?

I am no pro at this, so take my advise for what it is.....which is just my limited personal experience and research....cause when I posted this thread at beginning of this season...it was the first time I have done this process on gelcoat. You mentioned that you used compound after you wetsanded your boat, did you follow that up with a polish? Wondering if that is partly why scratches did not come out....or most likely, you did not work the 2000 grit and the compound long enough (just guessing here since the similar thing was happening to me when I started (black shows everything) and I went back and worked each step longer till I was happy with results).

Personally, I never used 1000 grit...1st, I did not have bad oxidation, was mostly water spots that was just the beginnings of oxidation (since previous owner dry docked and he just wanted to go surf for a few hours....then drop off the boat at the dock and let the marina deal with it, he never wiped it down after riding and beside when he bought and launched it, I don't think he ever even put the boat on the trailer again and took it out of the water himself. I know he had the marina detail the interior of boat a few times, but know he never had the hull polished/waxed in the 2 summers he owned it before I purchased it....the boat is much happier living with me, lol ) and 2nd, being that I have a black hull, I was scared that I would not be able to get the sanding scratches out like you mentioned. I started with 1500, then used 2000 (I got a sanding block from Lowes and cut large pieces of the sandpaper down to fit it since its much easier to use that way and after doing it for hours on end, its much easier on the hands too) and then compound and then polish. VERY time consuming to get it right but basically I got a spray bottle, filled about 3/4 full with water and added dawn dish soap and as I wet sanded I liberally sprayed on the soapy water. Again, I started with 1500 (which may not be aggressive enough if the oxidation is bad like you stated) but I would do about a 2ft x 2ft area at a time and first would go left to right...then up n down....then side to side. Before switching directions, I would use hose to spray off the area and clean it, then spray lots of soapy water and start the other direction. After working that area I would move onto the next, etc. Then I did it all over again with the 2000. Using the finer grit, I will tell you that some of the scratches from the forklift driver took me quite a while to work out. I could have gone more aggressive on it, but frankly I was scared to do that....so I just put in the extra time tho someone who knew what they were doing could have done it in half the time I spent on it.

IMO, the most important part of the process tho was the compound and polish process. I watched HOURS of utube videos before I attempted this myself and a good variable speed rotary was very important according to my research (I splurged and bought the Makita since I will always have a boat and figured if this went well I could do my own repairs for a long time to come), but brand is not important and as noted above, some of the other guys had just as good results buying the variable speed from Harbor Freight...the most important part is that you have a variable speed rotary (you dont want one of those $30 Wal-Mart brand things that does the irregular up/down & side/side motion, that will not work the compound properly. Then the PADS you use are also important cause they cut/polish differently. For the cutting compound....the yellow wool pads were recommended and for the polish, the white "semi-synthetic" pads. The wool is more aggressive and with the compound should remove the remaining wet sanding marks as long as you used the finer sandpaper long enough first....and the semi-synthetic white pads get the swirls and fine scratches out.

So from what I learned watching the video's on the compound and polish (and I verified first hand that this is true), is that the longer you "work" the compound and the polish, the better it does....basically the compound material breaks down as you work it across the gelcoat and goes from a grittier solution that is more abrasive to a finer solution as you work it and how much pressure you apply to the pad also matters. So I would take roughly a 2x2 area. I would dab about 6 dime sized dabs of the compound on the pad and then without starting the machine yet....would smear it over the area I was about to work (if you start it before then you will sling it everywhere). **PRO-TIP....cover your trailer, I spent an hour cleaning up my trailer after I was done with the boat cause I did not protect it with anything. Upside was that it needed to be cleaned anyway and I ended up polishing and waxing the trailer too** Anyway, I would start by setting the speed at around 600rpm (mine has settings between 1-6, I don't remember exactly what rpm is for each number)....but I started at the lowest #1 setting and putting a decent amount of pressure between the pad and the gelcoat would slowly work the area side to side and then up and down while overlapping passes, I did this process 2-3 times...then I upped the speed to about 1200rpm (setting #2) and did the same thing again with slightly less pressure.... and the last pass I did at about 1500-1600rpm with light pressure. (I read that its possible to "burn" the gelcoat if you go too fast and/or stay on one area too long). On some of my worse areas....I did the compound process noted above 2 times before I was happy and after doing entire boat, switched to the white pads and did the exact same process using the polish. After doing this, I understand why people charge a good deal of money for this service, its time consuming and a PITA. 

There are multiple great products out there that I am sure work great. I saw great results from 3M on some of the videos and some of the above posts highly recommend 3M, I personally bought the Boat Candy products and actually got a set of 3 bottles (crystal cut compound supreme, equiv to about 1200 grit.... crystal cut compound, equiv to about 1600-1800....and the crystal cut polish, equiv to about 2500 grit). I never used the compound "supreme", but sounds like in your situation it may be best to start off with that since its more aggressive, then the regular compound and then the polish.

Good luck....post up PICTURES of the before and after. Below is a link so you can resize the pics so they are small enough to post.

http://www.resizeimage.net/

[rhino89523 34]

I had to do real similar, when I bought my boat they had slammed the dock or something. I got a real good deal on the boat because of this and thought "I can live with some scratches" I didn't even make it all the way home before the OCD kicked in and I stopped at an autoparts store and started test sanding /polishing one of the areas. My wife was flipping out on me when we hadn't even used the boat yet and I am out in the backyard removing all the stickers and have the sides of the boat all wet sanded...which actually looks like crap until after you polish the boat. I basically stayed up half the night polishing the boat with my wife shaking her head and thinking i'd lost my mind. When we used it the next morning she was O.K.  the boat I like better without the tribal Avalanche stickers, and the scratches removed I think raised the boat value a good 5g or so...they were deep. I used the same process as infinity...but started grittier.

[namadio 0]

I still haven't made any progress on this project but was thinking about it today.  Going to be at the lake for 10 days for the 4th.  I committed to building a parade float... but might be a good time to start wet sanding =D