Factory Gel-coat repair class
- Thread starter sjboysen
- Start date
This question is for Scott, as I forgot to ask it during the class (perhaps this thread can be an ongoing source of info related to fiberglass repair.)
Anyway, I have a few 3/8" (+/-) holes through the foredeck of my Tom Cat where I had a drum windlass mounted for a couple of years. I would like to gelcoat them (they are filled with LifeCaulk now) but some of them are through the non-skid pattern. At the seminar, Scott demonstrated how to fill in a hole and then grind it down to make it fair with the surrounding fiberglass. But I can't (don't want to) grind down the non-skid. Do I just spray some gelcoat in there and accept the small inevitable unevenness?
Also, did I understand Scott to say that using LifeCaulk (or similar) was a bad idea? According to my rigger he has used it for this purpose for years without any water issues.
Thanks,
Warren
(Posted originally in wrong Gelcoat class thread.)
Anyway, I have a few 3/8" (+/-) holes through the foredeck of my Tom Cat where I had a drum windlass mounted for a couple of years. I would like to gelcoat them (they are filled with LifeCaulk now) but some of them are through the non-skid pattern. At the seminar, Scott demonstrated how to fill in a hole and then grind it down to make it fair with the surrounding fiberglass. But I can't (don't want to) grind down the non-skid. Do I just spray some gelcoat in there and accept the small inevitable unevenness?
Also, did I understand Scott to say that using LifeCaulk (or similar) was a bad idea? According to my rigger he has used it for this purpose for years without any water issues.
Thanks,
Warren
(Posted originally in wrong Gelcoat class thread.)
Warren,
Thanks for the question. I would recommend just grinding out the non-skid where your holes are, and having a proper patch done, however if this is something that you don't want to do, then have the holes filled with Duraglass, and then either spray on or dob in some gelcoat and call it good. You are not able to gelcoat over Lifeseal or any other sealant for that matter and have the patch last very long. If you are just filling the holes without worrying about cosmetics than filling with Lifeseal, Sikaflex, or 5200 is just fine.
I hope that this is clear enough but if you need clarification just give me a call or send me an email.
Scott
Thanks for the question. I would recommend just grinding out the non-skid where your holes are, and having a proper patch done, however if this is something that you don't want to do, then have the holes filled with Duraglass, and then either spray on or dob in some gelcoat and call it good. You are not able to gelcoat over Lifeseal or any other sealant for that matter and have the patch last very long. If you are just filling the holes without worrying about cosmetics than filling with Lifeseal, Sikaflex, or 5200 is just fine.
I hope that this is clear enough but if you need clarification just give me a call or send me an email.
Scott
I found out that the holes are filled with Formula 27, not LifeCaulk. Is this an acceptable substitute for Duraglass? If it is, I will gelcoat over it.
Thanks,
Warren
Thanks,
Warren
One has to be careful with "Bondo" type of fillers. They will crack. The Duraglass is less likely to crack. I like to put in glass fibers and make my own filler if the hole is more than miminal.
Although my question has not been answered about the "Thinner" for spaying, I assume that the gel coat has a surface agent, such as wax or PVA mixed in it.
For non skid you can fill with something like the "Duraglass" or your own filler and fibers. Make the repair slightly proud to the non skid surface, then sand flush to the surface, and use a Dremel tool to make cuts into the filler. Finally gel coat--and it will hard to detect.
Another trick is to put Cabosil in gel coat and put it on thick with a small roller to replicate non skid. This is the way that many of the C Dory 25 floors were done in the 2002-2005 era.
Although my question has not been answered about the "Thinner" for spaying, I assume that the gel coat has a surface agent, such as wax or PVA mixed in it.
For non skid you can fill with something like the "Duraglass" or your own filler and fibers. Make the repair slightly proud to the non skid surface, then sand flush to the surface, and use a Dremel tool to make cuts into the filler. Finally gel coat--and it will hard to detect.
Another trick is to put Cabosil in gel coat and put it on thick with a small roller to replicate non skid. This is the way that many of the C Dory 25 floors were done in the 2002-2005 era.
starcrafttom
Active member
Brent , to answer your question, no. I had read or been told before the you had to cover gel coat and did not understand why. I asked that question at class ans was told not to. In fact the factory could not think of a reason that you would.
To dr bobs question. I did not hear them mention any thing about adding a wax to the gel coat? again I know nothing about this. Is it already in the gel coat? My understanding from the class wasas followes.
1. fill and sand
2. clean surface with acetone
3. thin gelcoat in a bottle with the stated thinner (speed something)
4. spray the gel coat on the repair area
5. after it cures sand to match surrounding area
6. buff and wax.
after seeing it I have a better understanding of how to do it and will be making a few repairs on the 27.
To dr bobs question. I did not hear them mention any thing about adding a wax to the gel coat? again I know nothing about this. Is it already in the gel coat? My understanding from the class wasas followes.
1. fill and sand
2. clean surface with acetone
3. thin gelcoat in a bottle with the stated thinner (speed something)
4. spray the gel coat on the repair area
5. after it cures sand to match surrounding area
6. buff and wax.
after seeing it I have a better understanding of how to do it and will be making a few repairs on the 27.
Tom-
There are two types of resins: bondng and surfacing.
Bonding resins have two parts (resin and catalyst), which harden underneath when mixed together and applied, but the surface stays tacky (sticky), so that more subsequent layers can be added and will bond with the first. This allows layer by layer build-up of the hull or other fiberglass part.
Surfacing resins have PVA (poly vinyl acetate) or a wax added to them as well as the first two parts to create a hard surface. The PVA or wax comes to the surface, forms a barrier to prevent oxygen from getting to the resin, and thus the surface hardens as well as the resin underneath.
Gel Coat is usually a bonding type without the wax or PVA, but hardens because it is sprayed into the mold first, with many more layers applied afterwards.
If you use Gel Coat to do a repair and it is without wax or PVA, you must cut off the air (oxygen) to get it to cure hard, thus the wax paper or saran wrap layer is used.
If the Gel Coat has wax/PVA, the barrier is not needed, as those additives will cut off the oxygen.
The two parts of a resin combine to form giant continuous polymer molecules when mixed together. Oxygen interferes with their reacting and bonding.
Joe. :teeth :thup
There are two types of resins: bondng and surfacing.
Bonding resins have two parts (resin and catalyst), which harden underneath when mixed together and applied, but the surface stays tacky (sticky), so that more subsequent layers can be added and will bond with the first. This allows layer by layer build-up of the hull or other fiberglass part.
Surfacing resins have PVA (poly vinyl acetate) or a wax added to them as well as the first two parts to create a hard surface. The PVA or wax comes to the surface, forms a barrier to prevent oxygen from getting to the resin, and thus the surface hardens as well as the resin underneath.
Gel Coat is usually a bonding type without the wax or PVA, but hardens because it is sprayed into the mold first, with many more layers applied afterwards.
If you use Gel Coat to do a repair and it is without wax or PVA, you must cut off the air (oxygen) to get it to cure hard, thus the wax paper or saran wrap layer is used.
If the Gel Coat has wax/PVA, the barrier is not needed, as those additives will cut off the oxygen.
The two parts of a resin combine to form giant continuous polymer molecules when mixed together. Oxygen interferes with their reacting and bonding.
Joe. :teeth :thup
Captains Cat
New member
I hope there won't be a test, or if there is, I can sit behind you in class... :roll: 
Charlie
Charlie
Scott mentioned this. That is why the repairs he taught included the grinding the patch to a concave and using resin infused bi-axial and matting to fill. The clothe and resin creates the strength.
I can only assume the brand/type of gel coat used by Scott does, since he was very adamant that no barrier was required. He simply sprayed it on until proper coverage was achieved and let it cure/dry so the VOCs off-gassed, much like auto paint. Followed by sanding w/ a DA then cutting/ buffing.
starcrafttom
Active member
ok so what brand or type of gel coat do I buy? also I dont know how much speed what ever its called to mix with the gel coat??
This tutorial will hopefully help those that weren't able to attend the session @ the factory. I don't pretend to be an expert and I am not responsible for any outcome from the use of this tutorial. I am merely trying to convey, in words, what we all observed/learned. A huge mahalo to Scott for doing this for us. I suggest you read through this AND look at the pictures posted to get a better idea of what I am attempting to describe. Please post any questions/clarification you may require and I'm sure those of us that attended will chime in.
FIRST A WORD ON SAFETY. Please follow/use common-sense personal safety practices. Use eye & ear protection when using power tools. Use the proper gloves when handling/using chemicals and dust masks when creating dust/sanding/grinding. Properly dispose of any material used in this tutorial. Finally, make sure you have proper ventilation when using chemicals/resins. The filler & resins etc used in these procedures can create heat. Be aware of the possibility that FIRE/BURNS exists if they are improperly mixed. BE SAFE!!!!!!!
REPAIRING THROUGH HOLES:
Per Scott, this repair is for any through hole larger than ~1/2" diameter. It is the most difficult & time consuming, however, this repair is also useful for gouges and small holes that do NOT go completely through. The one caveat is you will only use the steps I will describe from the second Duraglass application on. In other words; for gelcoat gouges & small holes you will fill w/ Duraglass, followed by sanding w/ 600-800 grit using a D/A sander until smooth. From this step on it's a matter of spraying gelcoat and cutting/buffing on ALL repairs, including when you need to remove scratches. I will describe the spraying of gelcoat, cutting/buffing separately.
Materials:
"Duraglas" filler w/ hardener
Polyester resin w/ hardener
Bi-axial 0-45/90 clothe
Matt clothe
36-50 grit discs (for die-grinder)
320 & 600-800 grit discs (for D/A sander)
Acetone
latex/nitrile gloves/dust masks
Tools:
Die-grinder w/ disc head (or electric)
D/A sander (or electric vibrating sander)
putty knife(s)
small metal resin roller
disposable paint brush(es)
scissors
Begin by cleaning up the hole, removing any loose fibers/material etc. If it's a clean hole (drilled) that's good. If it's a structural location, like a transom, or visible on two sides, like a cabin wall/bulkhead this repair must be done to both sides. If not, one need only patch the rear portion with a cloth patch w/ fiberglass. Mix the Duraglas/hardener on a flat piece of plastic or clean wood etc using putty knife according to the instructions. Fill the hole with the mixed Duraglas and let dry/harden.
Once it's cured begin grinding the repair with 36 grit and the die-grinder. This is appears scarier than it is! Take your time!! Scott recommends a 3:1 ratio of repair/patch to hole; for example, if the hole is 1" grind 3" total diameter. You want to end up grinding into the Duraglas & surrounding area to create a ~1/8" concave "mushroom". Clean w/ acetone/rag.
Cut circles of bi-axial clothe starting at the size of the hole then slightly larger. You want two layers of bi-axial, the second slightly larger than the first but not larger than the final layer. Optimally, you make the center layer half of layer 1 and layer 3. The third/final layer is the matting cut to the size of the overall repair/grind-out you created (3" in the above example).
Mix polyester resin according to instructions. Begin saturating the clothe, one layer as you need/install it. Scott used a cardboard box & brush. Begin w/ the shiny side of the clothe down and saturate both sides w/ resin. If you still see white fibers after saturating, it's NOT saturated; brush on more resin. Begin adhering each cloth layer. Scott used a small metal resin roller. Roll across each previous direction @ 90/45 degree angles, varying it to remove all air bubbles. Continue the same with each successive patch. Allow to cure. Remember, COMPLETELY saturate the clothe & REMOVE all air bubbles. Scott impressed upon us that the resin/clothe is where the strength of the repair is achieved! The Duraglas is merely a filler and has no strength. It will crack if not sealed in resin/clothe. When this portion is done, you'll end up w/ ~1/16" high (convex) on the patch vs. the surrounding non-patched area.
Again, using the die-grinder & 36 grit, begin smoothing out the patch to cut down the hardened clothe/resin. You'll want to again slightly concave the patch ~1/16". What you're cutting down will be some of the matting; no problem. You can use a straight edge to make sure you're nice and concave in various directions. Clean w/ acetone.
Back to Duraglas. Mix another batch of just what you need. Fill the patch "criss-crossing" the patch with your Duraglas mixture, making sure it is completely filled slightly higher than the surrounding. Let cure.
Using the D/A sander and 600-800 grit pads begin sanding the patch. KEEP THE SANDER FLAT AGAINST THE SURFACE and take your time. You're complete when it's flat. Best way to check: using your flat palm/fingers, run your hand across the patch in various directions. Doing this w/ your eyes closed will allow you to feel even slight variations in level. Try it.
This completes this type of repair up to spraying on the gel-coat, cutting & buffing. I will explain that process separately.
FIRST A WORD ON SAFETY. Please follow/use common-sense personal safety practices. Use eye & ear protection when using power tools. Use the proper gloves when handling/using chemicals and dust masks when creating dust/sanding/grinding. Properly dispose of any material used in this tutorial. Finally, make sure you have proper ventilation when using chemicals/resins. The filler & resins etc used in these procedures can create heat. Be aware of the possibility that FIRE/BURNS exists if they are improperly mixed. BE SAFE!!!!!!!
REPAIRING THROUGH HOLES:
Per Scott, this repair is for any through hole larger than ~1/2" diameter. It is the most difficult & time consuming, however, this repair is also useful for gouges and small holes that do NOT go completely through. The one caveat is you will only use the steps I will describe from the second Duraglass application on. In other words; for gelcoat gouges & small holes you will fill w/ Duraglass, followed by sanding w/ 600-800 grit using a D/A sander until smooth. From this step on it's a matter of spraying gelcoat and cutting/buffing on ALL repairs, including when you need to remove scratches. I will describe the spraying of gelcoat, cutting/buffing separately.
Materials:
"Duraglas" filler w/ hardener
Polyester resin w/ hardener
Bi-axial 0-45/90 clothe
Matt clothe
36-50 grit discs (for die-grinder)
320 & 600-800 grit discs (for D/A sander)
Acetone
latex/nitrile gloves/dust masks
Tools:
Die-grinder w/ disc head (or electric)
D/A sander (or electric vibrating sander)
putty knife(s)
small metal resin roller
disposable paint brush(es)
scissors
Begin by cleaning up the hole, removing any loose fibers/material etc. If it's a clean hole (drilled) that's good. If it's a structural location, like a transom, or visible on two sides, like a cabin wall/bulkhead this repair must be done to both sides. If not, one need only patch the rear portion with a cloth patch w/ fiberglass. Mix the Duraglas/hardener on a flat piece of plastic or clean wood etc using putty knife according to the instructions. Fill the hole with the mixed Duraglas and let dry/harden.
Once it's cured begin grinding the repair with 36 grit and the die-grinder. This is appears scarier than it is! Take your time!! Scott recommends a 3:1 ratio of repair/patch to hole; for example, if the hole is 1" grind 3" total diameter. You want to end up grinding into the Duraglas & surrounding area to create a ~1/8" concave "mushroom". Clean w/ acetone/rag.
Cut circles of bi-axial clothe starting at the size of the hole then slightly larger. You want two layers of bi-axial, the second slightly larger than the first but not larger than the final layer. Optimally, you make the center layer half of layer 1 and layer 3. The third/final layer is the matting cut to the size of the overall repair/grind-out you created (3" in the above example).
Mix polyester resin according to instructions. Begin saturating the clothe, one layer as you need/install it. Scott used a cardboard box & brush. Begin w/ the shiny side of the clothe down and saturate both sides w/ resin. If you still see white fibers after saturating, it's NOT saturated; brush on more resin. Begin adhering each cloth layer. Scott used a small metal resin roller. Roll across each previous direction @ 90/45 degree angles, varying it to remove all air bubbles. Continue the same with each successive patch. Allow to cure. Remember, COMPLETELY saturate the clothe & REMOVE all air bubbles. Scott impressed upon us that the resin/clothe is where the strength of the repair is achieved! The Duraglas is merely a filler and has no strength. It will crack if not sealed in resin/clothe. When this portion is done, you'll end up w/ ~1/16" high (convex) on the patch vs. the surrounding non-patched area.
Again, using the die-grinder & 36 grit, begin smoothing out the patch to cut down the hardened clothe/resin. You'll want to again slightly concave the patch ~1/16". What you're cutting down will be some of the matting; no problem. You can use a straight edge to make sure you're nice and concave in various directions. Clean w/ acetone.
Back to Duraglas. Mix another batch of just what you need. Fill the patch "criss-crossing" the patch with your Duraglas mixture, making sure it is completely filled slightly higher than the surrounding. Let cure.
Using the D/A sander and 600-800 grit pads begin sanding the patch. KEEP THE SANDER FLAT AGAINST THE SURFACE and take your time. You're complete when it's flat. Best way to check: using your flat palm/fingers, run your hand across the patch in various directions. Doing this w/ your eyes closed will allow you to feel even slight variations in level. Try it.
This completes this type of repair up to spraying on the gel-coat, cutting & buffing. I will explain that process separately.
Well written tutorial. Generally one uses alternate layers of cloth and mat. Not sure how many layers you were using here. The idea is that the mat conforms to the warp and woof of cloth or roving, and smooths the repair, proximating glass to glass. The last surface of mat would be easier to fair when grinding smooth/concave. If you are doing any significant size of hole, it is important to grind out both sides of the damaged area, and apply glass on both sides, so that you have a new resin to resin/glass bond in the center. Thus the damaged area is less likely to delaminate. ( I know of one boat where the repair was only done outside--and half way between Cabo and San Diego, the patch came off!--almost sunk the boat.)
When not gel coating, I prefer epoxy and cloth to cloth, without mat.
Thinning gel coat to use in a Preval sprayer can be tricky. Both acetone and Styrene are used. If you use too much thinner, the gel coat will be soft and not cure properly. (15% is the max). I prefer styrene, but it is harder to find.
Great to see the factory involved with the owners and helping them understand the process of building and repair.
When not gel coating, I prefer epoxy and cloth to cloth, without mat.
Thinning gel coat to use in a Preval sprayer can be tricky. Both acetone and Styrene are used. If you use too much thinner, the gel coat will be soft and not cure properly. (15% is the max). I prefer styrene, but it is harder to find.
Great to see the factory involved with the owners and helping them understand the process of building and repair.
redbaronace
New member
Is there any chance that this class will be offered again in the future. I for one learn best by viewing a live demonstration. Would be a great opportunity to visit the factory and a nice way to meet some c-brats.
Jim Palmer
New member
Hi I have a new to me 1990 22 ft. C-dory with twin Honda 50's. I would like to find service in the area.
Anybody got any suggestions?
JIM
Anybody got any suggestions?
JIM
hi everybody. long time lurker looking for a hands on method of learning fiberglass, gel coat, non skid transfer, etc... I have a boat that used to be
[ Owed to Joy ]
I have been on the net looking into U-Tube and found a page called
Boatworks Today
this guy is fantastic for detailed info and methods on a lot of things related to boat repair. I have found all of my questions answered well enough to figure out the rest. only thing better would be if he would come to the west coast and give a hands on class! anyway I'm looking for some class recommendations for fiberglass repair. and info? I am buying a Blue Coral Cantilevered cover and I want to be prepared to repair any screwups before I start. any help is appreciated and I am always ready to stop and help any c-dory breakdowns on the road or water. funny thing is usually I am towing a bayliner. TEEHEE. Thanks, Lonny
[ Owed to Joy ]
I have been on the net looking into U-Tube and found a page called
Boatworks Today
this guy is fantastic for detailed info and methods on a lot of things related to boat repair. I have found all of my questions answered well enough to figure out the rest. only thing better would be if he would come to the west coast and give a hands on class! anyway I'm looking for some class recommendations for fiberglass repair. and info? I am buying a Blue Coral Cantilevered cover and I want to be prepared to repair any screwups before I start. any help is appreciated and I am always ready to stop and help any c-dory breakdowns on the road or water. funny thing is usually I am towing a bayliner. TEEHEE. Thanks, Lonny