fiberglass repair on hull

Thread starter #1
Finally have the sunfish dried out and ready to attempt repairs. Found two holes in the hull, both of them seem to start at the edge of the cockpit, and spread out from there. Looks like there is plenty of room between the outside of the hull and foam block, except for where it butts up against the cockpit. How do I put a backing in that will allow me to fill the hole, stay firm to the edge of the cockpit, and still allow flex in the area away from the cockpit?
Looks like previous owner had it filled with some type of bondo, and the crack just came back, I'm guessing because the material did not allow for flex.
 
#2
If you are trying to use foam as a backing for a fiberglass repair, you need to use Minimally Expanding Foam. Foam in a can like 'Good Stuff' can expand with some force. I've used it but I had a big enough hole that the extra foam could escape.

For other types of backing, see the thread done by MiniFish on his MiniFish. Wood, Cardboard and other types of material are often used as backing. The secret is holding it in place.

If there is not a inspection port on the rear deck there need to be a space for moist air to escape forward into the boat. Over the long term I don't think it really is too effective. A port on the back wall of the tub would be a better option.

Really trying to get away from 'Flex' as fiberglass does not like it and Gel Coat even less.
 
Thread starter #3
"flex" might not be the right word, but there is certainly a lot of "give" when I press down on the hull, on both sides of the boat. Just worried that if part of the repair actually hits the bottom of the cockpit and part of it doesn't, it would crack again.
 
#4
I had a problem with flexing under the cockpit also. Some SF had glue disks attaching the tub to the hull and others seemed to have the tub resting on the hull. The newer ones have foam strips on the corners of the tub. I had holes in the cockpit floor so that's where I injected the expanding foam. There should be no flexing of the hull under the cockpit when things are set up correctly. If you have a inspection port behind the splash rail, run your hand under the tub and see if there is a gap. Mine had the glue hanging down from the tub in spikes that punched holes in the hull. SF have been in production for so long, I would expect huge differences in quality from year to year. This forum seems to bear that out.
 
Thread starter #5
Finally took some photos of the problem.
I've got these two holes, next to each other. There are still some spider cracks I need to sand down, and a friend has suggested I just make it one big repair. That gray area is either a former repair, or the edge of the cockpit.
The photos from inside the inspection port show that there is some foam between the hull and the cockpit, but not everywhere, and nothing on the sides. Would it be best to inject some foam in the areas where there is none, and/or to inject foam into the holes themselves, so that the fiberglass has something behind it?
I have similar circular stress cracks on the other side of the hull that I still have to sand down. I am guessing I'll find the same type of holes there.
Any and all suggestions welcome. I've never tried anything like this before, and the sooner I have an idea of what to do, the sooner I can get the boat back in the water.
Thanks :)
 

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Wayne

Member Emeritus
#7
Finally took some photos of the problem.
I've got these two holes, next to each other.

The photos from inside the inspection port show that there is some foam between the hull and the cockpit, but not everywhere, and nothing on the sides.
I'm not clear on just where in the hull these holes are. Any chance you could post a wider shot for perspective?

The cockpit tub isn't usually surrounded by foam. In cases like Webfoot's, foam has been added for backup to repair areas.





 
Thread starter #8
Wayne, posting a wider photo of the hull, I've done a little more sanding.
Can't see the holes through the inspection port.
thanks,
Sue
 

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Wayne

Member Emeritus
#9
Finally have the sunfish dried out and ready to attempt repairs. Found two holes in the hull, both of them seem to start at the edge of the cockpit, and spread out from there. Looks like there is plenty of room between the outside of the hull and foam block, except for where it butts up against the cockpit. How do I put a backing in that will allow me to fill the hole, stay firm to the edge of the cockpit, and still allow flex in the area away from the cockpit?
Looks like previous owner had it filled with some type of bondo, and the crack just came back, I'm guessing because the material did not allow for flex.
Thanks for the wider view, that helps see the relationship of the damage to the rest of the boat much more clearly.

One approach might be to put an inspection port in the side wall of the cockpit. That would allow you to lay in a couple of layers of cloth & resin backing without too much trouble.

The port could later be fit with a cat bag for storage.



See this post for a couple of good fiberglass repair How To books and a video on gelcoat repair.

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Thread starter #10
thanks Wayne, that makes perfect sense and if all else fails I can try the inspection port, but I am trying to avoid cutting yet another inspection port into the boat.
I do have another question though, I've seen that gel coat repair video, and at one point it says that the top layer of gelcoat doesn't cure completely, and if you try to sand it, all you do is gum up your sandpaper. They don't really say how to cure that top coat. How would I do that?
thanks,
Sue
 

Wayne

Member Emeritus
#11
I've seen that gel coat repair video, and at one point it says that the top layer of gelcoat doesn't cure completely, and if you try to sand it, all you do is gum up your sandpaper. They don't really say how to cure that top coat. How would I do that?
Gelcoat is a polyester resin (fiberglass resin). It cures hard when air is kept away. This is accomplished in a couple of ways...

Gelcoat comes in two types, "laminating" and "finishing". It's the finishing type that contains the extra ingredient..., wax.

Polyester resin cures by internal heat created by the catalyst you add. This heat also causes the wax component of a finishing resin to rise to the surface and form a skin, sealing out air and allowing the resin to become fully cured.

If you are applying gelcoat in layers you need to have the "laminating" type to obtain the strongest bond between layers (coats). If you are going to achieve the full thickness in one application (this takes practice) you can use the "finishing" type.

To get a full cure of the final layer when using laminating resin, you can coat it with a paste wax after it's cured firm, but this risks blemishing the surface. The trick way is to spray it with PVA (Poly-vinyl Alcohol) ... commonly known as a liquid mold release agent. You may have noticed this being done in that Laser Performance video.

PVA is available from fiberglass material suppliers. Jamestown Distributors and West Marine carry it for about $18/pt. However, places like Discount Marine and Defender Marine, maybe even NAPA (in their jobber outlets), sometimes sell it for $18/qt so it's worth shopping around a little.



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Thread starter #12
thanks Wayne.
the video also talks about "patch booster" for thinning gelcoat and "dry guide" or "dry glide" for help in sanding. any idea where they have this? I've tried checking on the internet, but no luck on the patch booster, and since I don't know if it's glide or guide - no luck there either.
thanks,
Sue
 

Wayne

Member Emeritus
#13
the video also talks about "patch booster" for thinning gelcoat and "dry guide" or "dry glide" for help in sanding. any idea where they have this?
Unfortunately, in the LP video they don't make the distinction between what's readily available to the DIY fixer and what's typical for them as industrial boat builders.

Dry-glide may be that clay they rubbed over the patch to highlight spots that still needed sanding. I'm unfamiliar with it.

If you are going to spray on gelcoat as they did in the video, it needs to be thinned. The material for thinning is styrene.




If you are working in a production environment or when gelcoating in cooler temps, it's desirable for a job to cure quickly or with a little extra heat. For this they use "Patch Booster" a thinner and cure accelrator in one. Patch booster is an industrial level material not often found at consumer suppliers.

There are two ways to apply gelcoat, roll and/or spread -or- spray. If you want to spray, I strongly recommend you locate a specialty plastics (fiberglass & epoxy) supplier in your vicinity. This type of shop will have all the extras you'll need to accomplish a successful job.

This is an example of what I mean, though they aren't all so quaint.



Nothing but fiberglass supplies and staffed by people who really know fiberglass repair.




On-line, it's places like...

Fiberglass Supply

TAP Plastics

Fiberglast

Boatbuilder Central

US Composites

Mertons Fiberglass Supply

... to name but a handful

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#14
Time to ask more Gelcoat questions.

1.) With these two Evercoat brands of Gelcoat shown below, would the first be the "laminating" type, while the second is the "finish" type? The first requires a mold release, the second does not.

2.) In the Don Casey Gelcoat repair directions linked below, as previously posted up on this website, when the laminating type of Gelcoat is used, when do you put the plastic over the cure, immediately, or after an hour or two when the product has started to set up up? I would think that if you were to put in on right away, it would imbed itself into the Gelcoat, no?

3.) The Sunfish video states that a random orbital sander is the tool of choice. But can decent results be achieved by using a basic good palm or finishing sander? I'm referring to patches on the hull, not the deck.

4.) Using Sunfish OEM Gelcoat. The Sunfish video states that if you want to achieve maximum color matching, use the OEM Sunfish Gelcoat (available at APS). I have close to a 40 year old fish, in basically good condition. Even under these circumstances, isn't the white color of the OEM Gelcoat going to be somewhat off from the original color at this stage of the game, and thus, it's a crapshoot as to whether or not that OEM Gelcoat will even match up to begin with? Thus, with an much older boat, wouldn't an aftermarket gelcoat be just as good as the OEM brand as far as color matching? And, how far off is basic color white in any kind of repair?

I've also linked some Gelcoat repair instructions from the Jamestown Distributors (Rhode Island) website as well here - those videos were pretty interesting. Just click the "video" button below the product.

Jamestown Distributors Gelcoat instructions, link: http://www.jamestowndistributors.co...Name=Evercoat+One+Step+Finish+Premium+Gelcoat

Don Casey previously linked Gelcoat directions, link: http://www.boatus.com/boattech/casey/02.htm
 

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Wayne

Member Emeritus
#15
Time to ask more Gelcoat questions.

1.) With these two Evercoat brands of Gelcoat shown below, would the first be the "laminating" type, while the second is the "finish" type? The first requires a mold release, the second does not.

2.) In the Don Casey Gelcoat repair directions linked below, as previously posted up on this website, when the laminating type of Gelcoat is used, when do you put the plastic over the cure, immediately, or after an hour or two when the product has started to set up? I would think that if you were to put in on right away, it would imbed itself into the Gelcoat, no?

3.) The Sunfish video states that a random orbital sander is the tool of choice. But can decent results be achieved by using a basic good palm or finishing sander? I'm referring to patches on the hull, not the deck.

4.) Using Sunfish OEM Gelcoat. The Sunfish video states that if you want to achieve maximum color matching, use the OEM Sunfish Gelcoat (available at APS). I have close to a 40 year old fish, in basically good condition. Even under these circumstances, isn't the white color of the OEM Gelcoat going to be somewhat off from the original color at this stage of the game, and thus, it's a crapshoot as to whether or not that OEM Gelcoat will even match up to begin with? Thus, with an much older boat, wouldn't an aftermarket gelcoat be just as good as the OEM brand as far as color matching? And, how far off is basic color white in any kind of repair?
[ 1 ] Correct, laminating style stays tacky unless it's coated or covered to shut out air ... when you do that manual step you switch it to finishing off.

Finishing style has a wax mixed in that floats to the surface and seals it from air contact, thereby allowing it to fully cure hard without you needing to do anything extra.

[ 2 ] I wait, as you suggest, unless the gelcoat brand I bought has different instructions.

Keep in mind the snippets you find on-line are just the "Cliffs Notes" version of Don Casey's more in-depth repair and maintenance book series.


[ 3 ] In the LP open house video they mention using a "DA" type sander. The DA stands for Dual Action, a sander that orbits in two oval patterns at one time. This action minimizes the circular swirls a single action sander tends to leave on very smooth surfaces. The typical orbital or finishing sander is single action. DA sanders are often expensive by comparison so are not frequently found on home workbenches.

[ 4 ] I believe the LP OEM gelcoat matches today’s colors. Your boat was made 5 builders back in history so it's doubtful the color recipe has been preserved generation to generation. Not to mention the fade over time element.

Every gelcoat company has their own "white series"..., who knows what was used. If you want exact matching, get one of those color kits along with your can of white and read up (art books at the library) on how to tint for shading.

If you are re-coating a whole hull, it makes no difference ... use what comes out of the can, as is.


They're all called white
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#16
Besides the "laminating" vs. "finish" Gelcoat, turns out there is a difference in the types of base coat resins as well, as shown below. One is designed specifically for layering, the other for the final resin topcoat. However, via a conversation with Jamestown Distributors, you can put a "finishing" Gelcoat (read air-dry) right on top of the laminating resin, as the finish Gelcoat will cure the underlying tacky laminating resin.

I also found some additional "how to" directions a the links below that were extremely useful. Gelpaste (finish Gelcoat plus filler, just like Marine-Tex is epoxy resin plus filler) certainly sounds like the easiest way to go in a lot of minor repairs.

Link #1: http://www.pyacht.com/evercoat-laminating-resin.htm

Link #2: http://www.jamestowndistributors.co...o?docId=342&title=Spring+Time+Gelcoat+Repairs
 

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