Gel Coat and Fiberglass Repair

[alcoons]

Hi.

After my impressive double-twisting, three revolution back flip (or was it ending up sitting on a rock trying to emulate Kevin on the way back to Ordione?) I have some gel coat and a bit of fiberglass work to do. Looking for some good online descriptions and pictures. Have found:

http://www.atlantickayaktours.com/Pages/Ex...-Repair-1.shtml

for gel coat.

Any other suggestions? Where do I find Brian's great repair pages?

Thanks,

Al

[Bill Gwynn]

http://community.webshots.com/user/brian_nystrom

[Roger Turgeon]

Al;

I can probably help you with the fiberglass repair. I have plenty of extra glass and epoxy/hardener. I don't have much of a shop right now, though. Nor do I have any experience with gel-coat, though that's just a cosmetic issue.

Roger Turgeon

Night Heron, Cedar-strip

[glil]

This is timely information. I can't claim to have done any outstanding rock gardening maneuvers to do the damage, but one of my boats flew off of my car last night while driving 50 mph. Luckily it landed on the side of the road and not the pavement or another car, but it took a silver dollar size piece out of the top of the tip of the bow. I'm not sure how to assess exactly how much damage there is, but it is damaged into the fiberglass. It's an area where the fiberglass is thicker than other places. How do you tell how badly the fiberglass is damaged? If the fiberglass isn't damaged too deeply, does it definately need to be patched with fiberglass before the gelcoat? Also, can I use the boat in the meantime or should it be kept dry? And, I assume I should be able to get gelcoat to match the color? I read Brian's info, but still have questions as I haven't done any boat repairs yet.

And no, I didn't forget to tie the boat down. One un-named person "borrowed" the straps, left the boat on my car and didn't tell me that it was no longer tied on.

Thanks for any additional information.

Gay

[chetpk]

I have repaired boats, kayaks, rowing shell and worked with glass/epoxy in building some boats. Repairing these problems can be done by first timers and the information on the links above and in some back issues of Sea Kayaker magazine are all extremely helpful and will get you professional results.

If you have any concerns that some structual damage has taken place in the area in need of repair then I would put some small fiberglass patches on the inside of the hull. Years ago I talked to some commercial manufactures about what would be a good structual layup for a hull and what I remember from those conversations is that the total layup would equal 30 oz. when all is said and done. If you are working with 10 oz. cloth then three patches with each patch becoming slightly larger then your last one would give you your 30 oz. total with no pronounced edge or buildup showing. One can also put some of these patches on the inside and the others on the outside of the hull. The damaged area should be sanded and shaped so that its' outer edges create a bowl like shape going into the damaged area. Dremel motor tools work great for this. There sanding drums are probally a little more forgiving then their metal router bit. Hand sanding will suffice particularly if it is a small damaged situation. The epoxy and glass is then layed into the damaged area followed by gel coat. For smaller jobs an epoxy putty or thickened epoxy followed by gel coat is possible or just straight gel coat.

The nature of the damaged area will dictate what is used. If the glass fibers of the boat have been compromised or broken then a patch probably should be used. If the glass fibers weren't broken but are heavily exposed then one could use straight epoxy or thickened epoxy or an epoxy putty to go over the damaged area first then followed by gel coat. If it is just a chipped area or not a lot of the glass fibers are showing then just a gel coat should suffice.

Mask off the hull just outside of the damaged area to prevent epoxy, gel coat etc. from creeping into areas you don't want it to go. Whether or not you are doing a full fledge resin glass cloth repair or just a gel coat one, have some wide clear packing tape on hand. After you have put whatever you are going to use into the damaged area, put the packing tape directly on top of it. The tape will help you compress the materials together, keep the resins from creeping and will give you a repair job that will already be pretty flush to the rest of the hull after pulling the tape off. Don't worry about the tape coming off, it will, but make sure everything has cured under it first. On bigger damaged areas you can use Saran Wrap with tape over it. A new trick I just learned for very large size damaged areas is to strap a sand bag over the packing tape or Saran Wrap covered glass-resin repair job as the sand bag will help the glass to find and stay with the natural contours of that part of the hull till the resin cures.

If the area of damage isn't reall quite large enough to require patches of glass you can add specialized powders to the epoxy to thicken it up till it is like a thick cream and put that down first then follow it up with gel coat afterwards. Another product I have also used in situations like this and have had good success with it is something I get at my local ACE hardware store in the glue, epoxy section. It is called PC -11 and it is a marine grade two part epoxy putty that is no more then $5. It comes in a tube that looks like two old 35 mm film canisters that are back to back to each other and you simply take equal amounts out of each cannister then mix them and apply. It doesn't creep much like epoxy will and cures really hard. You also can get it in white or black. PC-11 might also be a good addition to someone's tripping repair kit as it will even cure under water.

[Bill Gwynn]

How do you tell how badly the fiberglass is damaged?

Gay

The simple test is the "Thumb" test. If the glass is easily compressed or if it feels squishy (a technical term) with your thumb, then it needs to be repaired. You can also kinda dig around with a sharp object as you are removing the cracked gel coat to look for soft spots. You can paddle it in the mean time especially if it's just gel coat damage, but keep in mind that it will need to be completely dried out before the repair can be done.

[alcoons]

The simple test is the "Thumb" test. If the glass is easily compressed or if it feels squishy (a technical term) with your thumb, then it needs to be repaired. You can also kinda dig around with a sharp object as you are removing the cracked gel coat to look for soft spots. You can paddle it in the mean time especially if it's just gel coat damage, but keep in mind that it will need to be completely dried out before the repair can be done.

Thanks for all the information so far. Very helpful.

Joel at NE Smallcraft suggested covering any areas with exposed fiberglass with duct tape if you are going to paddle before repair to minimize any water saturation. After each paddle, I remove the tape to make sure it dries if by chance moister gets in.

Al

[glil]

Thanks to all for the tips and information. There is no squishiness, but there are damaged fibers. Given the size (silver dollar) and location (on the deck at the tip of the bow), I will go with the PC-11 epoxy. Can anyone tell me where to find colored gelcoat? Could I order it from Impex? It looks like I would do the green (deck color) and then the yellow stripe on top of the green. Do I just mask on either side of the stripe and apply several coats of gel coat or is there a special way to do the stripe?

Thanks again, Gay

[chetpk]

Thanks to all for the tips and information. There is no squishiness, but there are damaged fibers. Given the size (silver dollar) and location (on the deck at the tip of the bow), I will go with the PC-11 epoxy. Can anyone tell me where to find colored gelcoat? Could I order it from Impex? It looks like I would do the green (deck color) and then the yellow stripe on top of the green. Do I just mask on either side of the stripe and apply several coats of gel coat or is there a special way to do the stripe?

Thanks again, Gay

Many Marinas and stores like West Marine will sell Gel Coat in various sized containers so I would start there. Some will sell color tint sets in which you mix up the color to match as close as you can to the color of your boat, then add that color tint (either straight or mixed) to the Gel Coat before applying it to the damaged area. I have never dealt directly with a kayak manufacturer for it, but have heard that some will send matching colored gel coat for repairs.

[chetpk]

Thanks for all the information so far. Very helpful.

Joel at NE Smallcraft suggested covering any areas with exposed fiberglass with duct tape if you are going to paddle before repair to minimize any water saturation. After each paddle, I remove the tape to make sure it dries if by chance moister gets in.

Al

Good point about keeping the area in need of repair as dry as possible. On a glass boat that is probaly a little less of an issues as a good blast from a hair dryer before starting the repair would probably remove any moisture from it before the repair is started.

On a Kevlar layed up hull it is probably is a more serious concern as Kevlar absorbs and wicks water so even though it might look dry, it could be retaining a little moisture which could compromise the ability of a good bond of new resin from properly adhering to it. A bare light bulb placed near the hull for a block of time might generate enough heat to really dry things out without being to much heat for the hull to be exposed to.

[Bill Gwynn]

Thanks to all for the tips and information. There is no squishiness, but there are damaged fibers. Given the size (silver dollar) and location (on the deck at the tip of the bow), I will go with the PC-11 epoxy. Can anyone tell me where to find colored gelcoat? Could I order it from Impex? It looks like I would do the green (deck color) and then the yellow stripe on top of the green. Do I just mask on either side of the stripe and apply several coats of gel coat or is there a special way to do the stripe?

Thanks again, Gay

You can order the gel from Impex and the color will probably be a pretty close match, or, you could just get white gel and pigments from NESC and try your hand at matching it yourself. Either way, it most likely will not be a perfect match. Also Brad at NESC should be able to give you some advise on mixing, matching and masking.

[alcoons]

Any suggestions on which Dremel Tool to buy? I never have quite needed one in the past. While I do a lot of home repair and some furniture building, I have the tools I need. I am really just buying it to work on my boat.

Thanks,

Al

[bob budd]

Check Brian's site or ask him directly. He found a dremel-like tool recently that was great for boat work and would be good for furniture work.

[Brian Nystrom]

Any suggestions on which Dremel Tool to buy? I never have quite needed one in the past. While I do a lot of home repair and some furniture building, I have the tools I need. I am really just buying it to work on my boat.

There's no need to use a Dremel tool on a repair that small, so unless you just want to have one (they're certainly handy), don't waste your money. If you are going to buy one, get a variable speed model in a kit with a bunch of accessories; that will be your best value for the dollar.

I only use power tools on boat repairs where they're really an advantage. Most people - myself included - are better off sanding by hand, as you can do a lot of damage with power tools in a hurry on a thin kayak layup. One slip, and you've got a much more involved repair on your hands. A good tool for working on fiberglass/kevlar/carbon fiber is a carbide scraper, but in your case, you can probably get by with 100-120 grit sandpaper on a curved sanding block. You'll also need a selection of fine wet/dry sandpaper in grits up to 800 at least and some polishing compound to bring back the gloss after sanding.

If you're going to try to color match the patch, don't buy white gelcoat unless the boat is a pastel color. If it's a bright, rich color, you'll never match it with tinted white gelcoat.

I'm not sure what you were planning to do with epoxy, but if there's no glass damage, you don't need it. Just apply the gelcoat and be done with it. Putting a layer of epoxy in the patch won't gain you anything and it could compromise the gelcoat bond (it will definitely slow down the repair process and make prepping for the gelcoat more involved).

[glil]

"If the area of damage isn't reall quite large enough to require patches of glass you can add specialized powders to the epoxy to thicken it up till it is like a thick cream and put that down first then follow it up with gel coat afterwards. Another product I have also used in situations like this and have had good success with it is something I get at my local ACE hardware store in the glue, epoxy section. It is called PC -11 and it is a marine grade two part epoxy putty that is no more then $5. It comes in a tube that looks like two old 35 mm film canisters that are back to back to each other and you simply take equal amounts out of each cannister then mix them and apply. It doesn't creep much like epoxy will and cures really hard. You also can get it in white or black. PC-11 might also be a good addition to someone's tripping repair kit as it will even cure under water."

"I'm not sure what you were planning to do with epoxy, but if there's no glass damage, you don't need it. Just apply the gelcoat and be done with it. Putting a layer of epoxy in the patch won't gain you anything and it could compromise the gelcoat bond (it will definitely slow down the repair process and make prepping for the gelcoat more involved)."

Bringing back this thread since I had a few more questions. I plan to use the PC-11 epoxy to fill in the area that chipped off the deck on the tip of the bow. (There IS glass damage.) Seems easy, fairly quick and seems to make the most sense. Was wondering about "the epoxy compromising the gelcoat bond". The PC-11 package states that "gel coats MAY not be compatible". Does this mean that some BRANDS of gel coat would be OK and others not? If so, anyone know which ones are OK? Or does it have nothing to do with the brand? What extra prepping is involved in preparing for the gel coat? The area is only about the size of a silver dollar.

Thanks, Gay

[chetpk]

"If the area of damage isn't reall quite large enough to require patches of glass you can add specialized powders to the epoxy to thicken it up till it is like a thick cream and put that down first then follow it up with gel coat afterwards. Another product I have also used in situations like this and have had good success with it is something I get at my local ACE hardware store in the glue, epoxy section. It is called PC -11 and it is a marine grade two part epoxy putty that is no more then $5. It comes in a tube that looks like two old 35 mm film canisters that are back to back to each other and you simply take equal amounts out of each cannister then mix them and apply. It doesn't creep much like epoxy will and cures really hard. You also can get it in white or black. PC-11 might also be a good addition to someone's tripping repair kit as it will even cure under water."

"I'm not sure what you were planning to do with epoxy, but if there's no glass damage, you don't need it. Just apply the gelcoat and be done with it. Putting a layer of epoxy in the patch won't gain you anything and it could compromise the gelcoat bond (it will definitely slow down the repair process and make prepping for the gelcoat more involved)."

Bringing back this thread since I had a few more questions. I plan to use the PC-11 epoxy to fill in the area that chipped off the deck on the tip of the bow. (There IS glass damage.) Seems easy, fairly quick and seems to make the most sense. Was wondering about "the epoxy compromising the gelcoat bond". The PC-11 package states that "gel coats MAY not be compatible". Does this mean that some BRANDS of gel coat would be OK and others not? If so, anyone know which ones are OK? Or does it have nothing to do with the brand? What extra prepping is involved in preparing for the gel coat? The area is only about the size of a silver dollar.

Thanks, Gay

[chetpk]

"If the area of damage isn't reall quite large enough to require patches of glass you can add specialized powders to the epoxy to thicken it up till it is like a thick cream and put that down first then follow it up with gel coat afterwards. Another product I have also used in situations like this and have had good success with it is something I get at my local ACE hardware store in the glue, epoxy section. It is called PC -11 and it is a marine grade two part epoxy putty that is no more then $5. It comes in a tube that looks like two old 35 mm film canisters that are back to back to each other and you simply take equal amounts out of each cannister then mix them and apply. It doesn't creep much like epoxy will and cures really hard. You also can get it in white or black. PC-11 might also be a good addition to someone's tripping repair kit as it will even cure under water."

"I'm not sure what you were planning to do with epoxy, but if there's no glass damage, you don't need it. Just apply the gelcoat and be done with it. Putting a layer of epoxy in the patch won't gain you anything and it could compromise the gelcoat bond (it will definitely slow down the repair process and make prepping for the gelcoat more involved)."

Bringing back this thread since I had a few more questions. I plan to use the PC-11 epoxy to fill in the area that chipped off the deck on the tip of the bow. (There IS glass damage.) Seems easy, fairly quick and seems to make the most sense. Was wondering about "the epoxy compromising the gelcoat bond". The PC-11 package states that "gel coats MAY not be compatible". Does this mean that some BRANDS of gel coat would be OK and others not? If so, anyone know which ones are OK? Or does it have nothing to do with the brand? What extra prepping is involved in preparing for the gel coat? The area is only about the size of a silver dollar.

Thanks, Gay

[/quote

Hi Gay,

I've been busy this week repairing two rowing shells for my son's rowing club that had everything from small gel coat chip issues right up to punctures through the hulls and one with the nose of the boat having been knocked off in a collision with another boat. Because the boats are outside and there is a race this weekend, my efforts to use standard epoxy and glass went south on me due to several issues (weather, old epoxy?, rain and maybe not enough catalyst), but the numerous repairs I did to the gel coat chips and small punctures that I did with the PC-11 to the damaged areas and the shell's gel coat, bonded completely. This being in the same conditions that my standard epoxy failed. I believe PC-11 is even designed to cure and bond even under water. My recommendation for repairs where the PC-11 is going to be forced through a small damaged area and allowed to partially lap over the boat's gel coat is to simply sand the gel coat first where the epoxy will lap over it. I then place a piece of packing tape over the PC-11 repair job to help give it a somewhat smooth and faired finish, then pull the tape off after it cures. The tape will not bond to it. Tonight I was back at the boat house pulling the failed to cure fiberglass cloth patches and standard epoxy with filler in it off the boat from a hole about the size of three quarters and replaced it with the PC-11 as they might need the boat as soon as tomorrow so it will be interesting to see how well PC-11 works over a hole of that size. Later I intend to sand that part down and still put a new epoxy glass cloth repair ontop of the PC-11, but hopefully it gives us the temporary fix we now need. Where I have used the PC-11 on some of my home made kayaks, commercial kayaks and a well used 17 year old canoe, I have had no failure issues from the PC-11 including where it went over small gel coat sections.

Scott

[glil]

Thanks Scott,

I just used the PC-11. Took all of about 2 minutes to fill in the area-couldn't have been any easier to use in this situaton. It's not pretty yet, since the area used to be green and yellow, but I'm assuming it will sand easily and I'll eventually try the gelcoat. I was wondering more about the bond with the gelcoat that I will put over the epoxy vs epoxy on a little bit of existing gelcoat.

Anyway, the boat will be ready to use for the weekend.

So, thanks for the info.

Gay

[Brian Nystrom]

The issues with epoxy and gelcoat are :

1. The epoxy must be FULLY cured before applying gelcoat. Depending on the ambient temperature, that can take from a day to several weeks. Applying heat with a lamp or heater can dramatically accelerate the curing process and reduce it to a matter of hours (overnight) with most epoxies.
2. The epoxy surface must be completely clean before applying gelcoat. This means washing it with water to remove any amine blush. I typically go over it again with lacquer thinner or denatured alcohol to remove any oily residue.
3. Gelcoat will not bond chemically to epoxy, so you need to improve the mechanical bond. That means sanding with relatively coarse sandpaper to give the surface some "tooth". I use 80 or 100 grit for this.

If you prep it properly, you should have no problems getting a good bond. I have yet to experience a bonding failure with a gelcoat-over-epoxy repair.

[glil]

The issues with epoxy and gelcoat are :

1. The epoxy must be FULLY cured before applying gelcoat. Depending on the ambient temperature, that can take from a day to several weeks. Applying heat with a lamp or heater can dramatically accelerate the curing process and reduce it to a matter of hours (overnight) with most epoxies.
2. The epoxy surface must be completely clean before applying gelcoat. This means washing it with water to remove any amine blush. I typically go over it again with lacquer thinner or denatured alcohol to remove any oily residue.
3. Gelcoat will not bond chemically to epoxy, so you need to improve the mechanical bond. That means sanding with relatively coarse sandpaper to give the surface some "tooth". I use 80 or 100 grit for this.

If you prep it properly, you should have no problems getting a good bond. I have yet to experience a bonding failure with a gelcoat-over-epoxy repair.

[/quote

Thanks for the info, Brian. Sounds easy enough. What is amine blush?

Gay

[Brian Nystrom]

Thanks for the info, Brian. Sounds easy enough. What is amine blush?

Gay

Amine blush is a waxy substance that forms on the surface of many epoxies as they cure. If your epoxy doesn't specifically state that it's "non-blushing", it will probably blush to some degree. Blush prevents other materials from bonding to the epoxy and can even prevent them from curing at all, so it must be removed. Washing will remove it, but I usually end up scraping the surface to shape it anyway, so the blush gets removed in that process. Sanding is not as effective as scraping, as it can actually drive the blush into the surface, so the surface must be cleaned before sanding.