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Foredeck Shuffle

Peeling Gelcoat Project - Laser

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5 hours ago, Foredeck Shuffle said:

Cross linking this because I need an answer quickly before this boat hits the water.  If you understand fiberglass hulls well, do me a favor and read/reply to this post.

Peeling Gelcoat Project - Laser

Hey DB - send her out sailing. Water will not bother the boat. The sun when it sits on a rack likely does more damage. And as said the repair is easy if you have done any gelcoat work before. Good luck!

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Gel coat bond to laminate :  ”Normally” gel coat is sprayed into a mold at .020 “ wet film thickness. It cures before you laminate, but not completely.  Gel coats are “air inhibited” which means that the very top surface does not completely cure, but remains “open” and cures when covered by the laminating resin.  

Further, the styrene in the laminating resin, softens and etches into the gel coat further facilitating a good bond.  If the gel coat is not applied thick enough, the styrene will cause the gel coat film to wither and die, a thing that looks like lizard skin called a Gator is the result.

the gel coat\ laminating resin is well understood and not a mystery.  I can’t really explain what caused the problems on your friend’s Laser, except for some wholesale contamination of the open gel coat.  This would have to be something like an oiled airline exploding all over the mold,  or guys with oil on their hands.

When patching Gel coat it is not unusual to add  wax to the gel coat which floats to the top of the film and allows the entire thickness to cure.  There are also specialist gel coats for painting interiors that have different chemistries to eliminate the thin sticky surface of an ordinary in mold coating.  Maybe this boat was sprayed with the wrong stuff, but those things aren’t supposed to happen in factories.

SHC

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On ‎9‎/‎8‎/‎2019 at 5:28 PM, Steve Clark said:

Gel coat bond to laminate :  ”Normally” gel coat is sprayed into a mold at .020 “ wet film thickness. It cures before you laminate, but not completely.  Gel coats are “air inhibited” which means that the very top surface does not completely cure, but remains “open” and cures when covered by the laminating resin.  

Further, the styrene in the laminating resin, softens and etches into the gel coat further facilitating a good bond.  If the gel coat is not applied thick enough, the styrene will cause the gel coat film to wither and die, a thing that looks like lizard skin called a Gator is the result.

the gel coat\ laminating resin is well understood and not a mystery.  I can’t really explain what caused the problems on your friend’s Laser, except for some wholesale contamination of the open gel coat.  This would have to be something like an oiled airline exploding all over the mold,  or guys with oil on their hands.

When patching Gel coat it is not unusual to add  wax to the gel coat which floats to the top of the film and allows the entire thickness to cure.  There are also specialist gel coats for painting interiors that have different chemistries to eliminate the thin sticky surface of an ordinary in mold coating.  Maybe this boat was sprayed with the wrong stuff, but those things aren’t supposed to happen in factories.

SHC

Thank God!  Someone who understands gel coat!  Now, re-gel coating IMHO would be a lot harder than simply removing the peeling gelcoat and simply repainting the hull.  Sure a gel coat patch is fine, but re-gel coating an entire hull is way more involved.  I believe the finish from a nice marine paint job would ultimately be much more even, fair, easier/faster to do and significantly less expensive.  Yes, gel coat provides a protective layer between the glass and elements, but just keep the hull covered when not sailing and you'll be fine.  Boat will be a bit lighter as well.

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If you want to go down the rabbit hole of the gelcoat vs. paint question then check out the Boston Whaler forum. Extensive discussion with links to professional resources about the pros and cons, role of gelcoat in the build process, gelcoating over epoxy repairs, etc.

http://www.continuouswave.com/whaler/

I have a ‘71 Whaler that I am restoring, having removed the completely crazed original gelcoat. I also have a ‘74 Laser that I’m working on. My intention for both boats is to go back with gelcoat. I’ve gone back and forth in my decision making. I’ve seen good results both ways. We’ll see how it goes....

 

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25 minutes ago, Old Yeller said:

If you want to go down the rabbit hole of the gelcoat vs. paint question then check out the Boston Whaler forum. Extensive discussion with links to professional resources about the pros and cons, role of gelcoat in the build process, gelcoating over epoxy repairs, etc.

http://www.continuouswave.com/whaler/

I have a ‘71 Whaler that I am restoring, having removed the completely crazed original gelcoat. I also have a ‘74 Laser that I’m working on. My intention for both boats is to go back with gelcoat. I’ve gone back and forth in my decision making. I’ve seen good results both ways. We’ll see how it goes....

 

Completely different use cases no?  The Whaler lives in the water or sits on a trailer and the bottom takes abuse getting on and off that trailer.  The Laser lives on a rack, sitting on its deck usually (ideally with a bottom cover to protect from sun).  YMMV but if it was me I would handle those two boats very differently if refinishing the bottom. 

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35 minutes ago, Wess said:

Completely different use cases no?  The Whaler lives in the water or sits on a trailer and the bottom takes abuse getting on and off that trailer.  The Laser lives on a rack, sitting on its deck usually (ideally with a bottom cover to protect from sun).  YMMV but if it was me I would handle those two boats very differently if refinishing the bottom. 

No sir I don’t think they are completely different. Both situations deal with a gelcoat that for various reasons failed to the point that it needed to be removed and replaced (with something). I mentioned the Whalers because this is a common problem when restoring  the old hulls, and there are a lot of discussions and resources out there for dealing with it. Thought it might be helpful because this situation is not common in the Laser world. 

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7 minutes ago, Old Yeller said:

No sir I don’t think they are completely different. Both situations deal with a gelcoat that for various reasons failed to the point that it needed to be removed and replaced (with something). I mentioned the Whalers because this is a common problem when restoring  the old hulls, and there are a lot of discussions and resources out there for dealing with it. Thought it might be helpful because this situation is not common in the Laser world. 

Note I said "use" case.  I maybe misunderstood you. Thought you were saying you were working on refinishing the bottom of both these boats (old Whaler and Laser).  If so (that the gelcoat eventually failed likely to varying degrees in varying places due to age and - likely different forms of - abuse) then what I was suggesting was that the approach to refinish them might be different because the use case is different once refinished. Having owned and worked on both I sure would take a different approach but like I said YMMV!

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Update.  All parts replaced, new vang, some other new parts, others from parts I had, cut down a spare full bottom section I had to Radial size, replaced vang strap with plate for vang key, new plastic caps, boat is in XD configuration except I did not use the 2018 hiking strap rigging method.  Hull wet sanded down, tedious but the results were good and it is a lime green hull.  The hull is stiff and the smell of off gassing from the long past filled the garage while re-bedding or replacing everything.  Minor repairs to foils to prevent water ingress in case there is foam in either.  Various lines were color coordinated with different colors of green and orange except the gray mainsheet buzzline, we are going for a 70's vibe.  Still need to finish compounding, polishing, and waxing this weekend and then she will go sailing and racing.

This winter the gelcoat will be sanded down more aggressively, matched lime green gelcoat sprayed in the spring, sand, compound, and polish again.  Damage to the foils ground back out, filled, sanded, and gelcoated international orange, polished back to standard Laser form.  Wood hand rails and tiller revarnished, new carbon tiller extension added.  I suspect this boat will look nicer than most of the boats in our yard.

Thank you to the folks that answered the gelcoat question, gave confidence to get the boat in the water asap and do a correct job during the winter.

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Of course you are aware that the Standard lower and Radial lower are different extrusions.

A cut down standard lower is not a class legal radial lower. Furthermore the two bend differently and this will effect how the boat performs. Other than that, you are being a champ getting this kid on the water.

SHC

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Also Radial bottom section has an internal sleeve making it much stiffer. Might find cut down standard does not last long

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Didn't know about sections, I have several standards and the one I cut is from the 70's.  Found a used Radial section for nothing.

Boat awaits compounding and wax (her project now), otherwise complete with a good practice sail.

76CANLaser.png

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2 hours ago, Foredeck Shuffle said:

Boat awaits compounding and wax (her project now), otherwise complete with a good practice sail.

Is that gelcoat you sprayed on?

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2 minutes ago, Old Yeller said:

Is that gelcoat you sprayed on?

No.  Based on advice from those that know and posted a reply here, decision was to wet sand, compound, polish, and go sailing.

This winter the old gelcoat will get sanded more thoroughly and new gelcoat spayed.

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Gelcoat:

We usually thin About 3:1 with acetone and apply about five or six full wet coats. 
 

A liter of mix will probably be enough for the first coat. The last coat might consume two liters. 
 

A gallon of gelcoat would be awfully minimal and sanding through while finishing would be likely.

we use about four gallons on the topsides of an Ensign and over five gallons on a J-24

we IMMEDIATELY begin to mist on apply about a quart of PVA . Sealing away the air is very important. Making runs in the PVA is disastrous. 
 

using green PVA I am applying it too fast if I can see the first couple layers. 

I might spray on ten coats or more of PVA to be certain I have a great seal coat. It can take an hour to spray the PVA on a cool day.  On a damp day... just don’t even start spraying the gelcoat. Your job will be crap 

We have some 40 year old 12,000 rpm Porter Cable half sheet sanders. If you want a beautifully fair job, they can be used to accomplish that task. 
we start with 320 and sand away the PVA and the shine. 
we mark the entire surface with 3m Guidecoat and finish removing the orange peel with the 320. 
technique: It is best to use any fairing or polishing sander as though it doesn’t have a motor. By that I mean, sand as though the tool is a sanding block. Make the same strokes you would make if you were using a sanding block. 

 What?? The sander’s motor makes it sand a lot faster than a block. If you hold the 12,000 rpm sander in one place for ONE second that gouges your job just as bad as if you sanded the exact same stroke TWO HUNDRED TIMES!!!  
Keep the sander moving.

Odds are I would use a 6” DA sander to sand out the gelcoat. It is a Laser. They are all a bit wavy. I don’t see any point taking an extra day to make the boat more fair than anybody else’s boat and I can make it nearly perfect with a DA.

After the 320 I would run a buffer over it with whatever is the nastiest available  buffing compound. Presta Super Cut works great 

after making certain all the orange peel is gone we switch to 400 wet and remove all the machine made 320 sanding swirls 

The 3m Guide coat makes that task simple ... but still a lot of work

 

Apply guide coat again and sand with 500. Usually that is fine enough paper to give the appearance of perfection

 

as for under the gunwales, I sand with a flexible sanding “block” I create out of sandpaper 

 

I stack Eight or ten 9 x 11 sheets and cut them in half —- 9 x 5.5

then I stack them together and fold them in half 5.5 x 4.5

i use a pencil and write LAST on the inner sheet. 
as each sheet wears out I place it on the inside and when LAST shows up I go cut more paper. 
depending on what jobs we are doing, some of those “kits” last me for years. I store them under the sleeves of sandpaper so they won’t curl up when they dry. 
 

No Guidecoat?? you can use #1 pencils and scribble all over the gelcoat. I never had Guidecoat until 3m invented it late last century. 

#1 pencils seem to be special order anymore. Just order some 

when sanding under the gunwales you need to make certain you continuously rotate your sandpaper stack so the edge doesn’t make a groove. 
restated... if you hold the paper square to the gunwales and stroke away you will make a nasty groove on the hull side .  You want to make EVERY  stroke unique. Sometimes the pointy corners stick straight up. Sometimes the edges line up. Sometimes your paper doesn’t teach all the way to the edge of the gunwale. You do not want to have an obvious transition between your machine sanded area and your hand sanded area. Spread that transition by clever varied use of your abrasive sheets. 

 

in fact... the paper will chew right through the gelcoat on the inside of the hangy down part of the gunwale,

it is hard to spray gelcoat on the inside of that outside edge.
and 

it is a whole lot easier to apply pressure to the paper at the edge than down in the inside turn of the underside of the gunwales . It is best to not even start sanding the inside turned down sort of the gunwale until everything else is finished. I rarely even sand it with the 320until the 509 is finished everywhere else. 
why!! I can see that it hasn’t been touched. That is a good thing. 

take your time!!! If you start to see you are sanding through somewhere,,,, DONT Sand  THEre Any MORE!!!  

 

when you finish sanding and buffing you will have very porous gelcoat. Wax is not a good idea. 
but good car wax like Maguire’s Gold Class or Turtle Platinum wax does wonderful stuff vs weathering...

my favorite compromise is Gel Gloss . It has a little carnuba wax but it mostly has some sort of runny chemical that acts like hand lotion on gelcoat.

i generally slap some on and polish it off with the buffer pad I used for the Super Cut. Then I give it a rundown with a nice terry cloth towel. 
 

over that I love to use McLube racing polish. I don’t believe any of the nonsense about going faster but that crap is SLIPPERY ! If I apply it to my Laser I can slide it onto the varieties dock with a couple fingers under the bow. When it has worn off I have to pull with both hands. 

 


 

 

 

 

 

 

 

 

 

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17 hours ago, Gouvernail said:

as for under the gunwales, I sand with a flexible sanding “block” I create out of sandpaper 

  

I stack Eight or ten 9 x 11 sheets and cut them in half —- 9 x 5.5

then I stack them together and fold them in half 5.5 x 4.5

i use a pencil and write LAST on the inner sheet. 
as each sheet wears out I place it on the inside and when LAST shows up I go cut more paper. 
depending on what jobs we are doing, some of those “kits” last me for years. I store them under the sleeves of sandpaper so they won’t curl up when they dry. 
 

 No Guidecoat?? you can use #1 pencils and scribble all over the gelcoat. I never had Guidecoat until 3m invented it late last century. 

#1 pencils seem to be special order anymore. Just order some 

That entire post was some good hands on info! I’ll have to try the stack of sandpaper idea. I remember a guy from England showing me the pencil technique  when I was a kid working in a boat yard in Texas. 

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