Sanding Hull - What grit sandpaper have you used.

jme097

Guys - I got my 280 last summer (July) and its never been bottom painted as it was kept on a heated rack its whole life year round. I am thinking about epoxying the bottom and applying VC Offshores this spring. I did this on my old boat before I sold it and it turned out great. What grit sandpaper would you suggest for sanding the hull? I used 60 grit on my previous boat but there was also 3 coats of bottompaint I was trying to get off. 

Any suggestions would be much appreciated! I am thinking about blocking the boat in my driveway and attempting this myself. (paying a profession to block/unblock of course). I was thinking of using 80 or 100 grit as I have minimal sanding prep to do. 

Michael T

@jme097, I edited what I said as I just got a return call from the best gel coat guy in the area and his advice contradicted mine so here's the best advice I can forward to you:

Clean the hull thoroughly so that you remove any old wax and debris or you'll just sand that into the hull. 

If you have any serious dings in the hull this would be the time to use fairing compound. Most of these are two part epoxies - but that's just for damage.

Then the sanding. You want to remove any of the shine from the gel coat to ensure adhesion. Use 80 grit but don't over sand - just remove the shine from the gel coat.

After this the hull must be thoroughly washed and dried. Then you should wipe it with acetone as a final prep for your barrier coat.

You should use a premium barrier coat. This coat (more like 2 or 3 coats) is more important than the final bottom coat that you see as it is the barrier coat that stops water penetration into the hull. There are a number of good ones, personally, I like Interlux  InterProtect 2000E. This was used by the guy I just talked with on my 2014 EC 360.

I would consider it even more as you are contemplating using an Interlux finish bottom coat - VC family product - VC17, VC Performance, VC Offshore! 

I think you can easily do this project yourself and do an excellent job of it while saving money.

The guy I talked with is presently working on a dozen bottom coat procedures at three different marinas. He was just speaking with Interlux paints regarding their latest products and procedures.

Good luck! MT

Handymans342

Michael, could you please call him back and ask him how many times you can wet sand the hull sides to bring back the gel-coat before damage occurs? Blue in my case. This was just done on mine for the first time. They started with 800 and second with 1000. Looks fairly good considering. Thanks!

Michael T

Steve, I'd be glad to ask him. From previous conversations I know he has said that gel coat is thicker than many boaters realize and that it can be wet sanded a number of times if done properly. I have heard him telling a boat owner that he would be using 600 then 800 then 1000 - after that he'd be compounding and then waxing. BUT - I will call him for specifics. Although he does all boats and just finished a 75 foot Marquis he is a real expert with Rinkers. He likes Rinkers as there is lots of gel coat on them.

Handymans342

Yeah well their gelcoat in the engine room was a horrible install. Lot of us has peeling chips

Michael T

Interlux or Pettit have the cure for that - wash, dry, acetone, dry - paint!

Michael T

Hello Steve, I got a call back and also contacted another gel coat person that I have seen working on high end boats at my marina. Both said essentially the same thing. Rinker is not cheap with their gel coat. they lay it on thick. The sanding you have described is completely normal. How many times could it be done? They both said three good wet sands for sure......

But both technicians said the same thing: "Why would your friend be thinking of repeatedly wet sanding his colored hulls sides? Wet sanding should only be used to remove scratches from damage or poorly done buffing NOT as any sort of routine maintenance. Once the wet sanding has been done to restore the color, the base the area could be - if required - compounded with a very light compounding product - VERY light - and then finished waxed.  After that the hull color should be maintained by waxing as necessary. In the future, if the hull gets discolored beyond the help of a waxing use a compounding rather than a wet sanding, if possible""

My favourite gel coat guy noted that you lived in Florida and said "suggest to your friend (Steve) if his boat is oriented so that the sun shines on one side of the hull all day that he assess the cost of having a side curtain of material made for that side of the boat to keep the sun off it. Best cheap insurance."

BTW, when I had my boat lift the sun shone on the port side of the boat lift for most of the day. I had an inexpensive (compared to gel coat repair) side curtain made that blocked the sun from that side. It worked like a charm.

Handymans342

I wasnt going to keep repeatedly wet sanding the hull MT only that is was needed once to bring back the shine because it was never waxed and sat in the sun.  The curtain is going to be on my list!

Dream_Inn

....waiting for Ras to ask about the drapes.    You could make it look like a hula skirt and have the roof look like a tiki hut!

Handymans342

Great Idea. Go see your DAD DI

rasbury

that is a really good idea Al, I was thinking about that when I cleaned my boat up- mine was not SUPER bad but it did need paper. It does get hard to tell where you finished....keeping it consistent.  I think I started with 1000 and then finished with a much higher as I figured a little more time vs. using something to corse was a better course of action. I am not experienced at all doing that. Then I came back with 3M heavy oxidation, then buffed with a finishing material (Maquires I think it was) and then waxed. It looked awesome...Fl. sun however killed it in about a year. I don't think I will need to sand this year at all but I will probably hit it with the 3M heavy oxidation (will start with the lite product) with either my orbital or buffer, which ever is needed to get the job done. As far as those curtains, I was thinking about something like that- I need a new mooring cover as mine is toasted. I still put it on but I also put a tarp over the front half to protect the front of the topside as well as go over the glass as the cover in that area is "transparent" I am actually considering trying to make one myself. The cheapest I have found to have anyone make that cover is a grand. I realize the material is pretty expensive for the Sunbrella type stuff and perhaps the cost is more material than labor.  I would make it go over the glass in stead of snapping along the top so it blocks out all of the sun into the helm and beyond. Then, I would put some ilets down along both sides and then make that curtain, attach there and also bungie cords to hold the bottom to the trailer and I would make those curtains go all the way to the front of the boat...I might also make a piece that would cover the front deck also-pretty much cover the whole thing up. That way, I could also leave the windows open and get some air circulation going as well. It might get me another year before the boat would need waxing again, really protect the seats. Might even make a flap that would come down and cover the tires as the sun eats those up to just sitting.  You could easily add those ilets to an existing cover also I would think and if your on a lift would probably only need one side. Mine sits on a trailer at a yard and I never know where the final resting place will be once I drop it off....just another thing on my list. When I hit the 650M lottery, I will be riding in one of those 410 or what ever there were and I'll just put Al on the payroll to keep everything working right!

Michael T

If you are talking about sanding the hull "bottom" - if the original bottom coat job was done properly there should have been a barrier coat applied (usually a 2 part epoxy) that is a special blue or gray colour that is unlike most final bottom coat ablatives. That way if you want to scuff your ablative coat to avoid too much build-up  when re-coating or you want to completely replace your ablative coat you do not over sand and sand into your barrier coats as the blue or gray will show through. If there was no bottom coat done and you are sanding fresh gel coat - removing the "shine" is all you have to do.....and it is easy to see when you have done that as a dull look quickly presents itself.  A lot of common sense here not too much complication is required.