My decks are soft, left and right (red/green, port/starboard etc) just forward of the rear transverse
beam. The areas are approximately 8” by 30”. Are Gcat decks constructed so that the technique of
Drilling through the outer rigid deck, then through the middle core and filling with resin will work?
If not, then do I install access ports in the decks and repair From the inside?
Any ideas or help?
Thanks

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82 GCAT 5.0
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I’m not sure how the G Cat hulls are constructed, but you could determine pretty easily if they are solid laminate or foam core by carefully drilling a small hole (like 1/8” diameter) into the deck. This will tell you right away if there is a foam core and therefore what type of repair method is appropriate. Just be careful and go slowly because if the hull is foam core, you don’t want to punch all the way through since that would allow your epoxy to leak into the hull when re-bonding. You probably want to use a drill stop set at about 1/4”.

sm

They are foam core. I used an alternative solution to the traditional fiberglass repair that was simple, easy and effective on my G-Cat 5.7...

I turned the boat upside down and spread 2-part high density foam as thinly as possible to completely cover the soft areas. It expanded to about 1 inch thick layer and hard as a rock.

here is the product I used:

https://www.homedepot.com…S73bX-jtoCFU4fHwod-AYBvQ

You have to be quick. You have about 3 mins from mixing to application. Full set in 20 mins. I used a disposable foam brush to spread the mixture out.

Good luck!

Brad

Quote

They are foam core. I used an alternative solution to the traditional fiberglass repair that was simple, easy and effective on my G-Cat 5.7...

I turned the boat upside down and spread 2-part high density foam as thinly as possible to completely cover the soft areas. It expanded to about 1 inch thick layer and hard as a rock.

Can you elaborate on this? You spread the foam on the inside skin through an access port? Or you spread it on the deck itself? I plan on doing the repair soon on my 5.7. Thinking of either trying the injection method, but really want to just cut the top skin off in the affected area put some cloth and epoxy back over the core and then put the skin back on. My area is a lot smaller than the OP. 30 inches seems long

Their are several repair methods that can be used in the instance, I will go through the most right to the least right:

1) Cut out the entire affected area and replace the entire section, glassing across the seams, shooting new gelcoat etc. Watch the latest Team Vestas Wind video to see what I mean. This isn't a great option for most of us because you have to fabricate a mold off the existing area to make the replacement part from.

2) Cut out the affected outer glass skin then route out the bad core and let the inner laminate dry out inside for a few days with some desiccant. Then replace the foam (PVC core most likely) and outer laminate. I would add additional fiber reinforcement in the area beyond what was removed (assume 0.010" per layer) when glassing over the new core. There is a reason the laminate went soft in the first place, and that is not enough glass in that area.

3) Inject resin into the soft spots. This isn't really solving the issue (weak laminate or rot due to moisture), but I have done it myself and it does work. I wouldn't do it on a serious race boat (its heavy), or a boat I was going to keep forever.

jalex

Quote

They are foam core. I used an alternative solution to the traditional fiberglass repair that was simple, easy and effective on my G-Cat 5.7...

I turned the boat upside down and spread 2-part high density foam as thinly as possible to completely cover the soft areas. It expanded to about 1 inch thick layer and hard as a rock.

Can you elaborate on this? You spread the foam on the inside skin through an access port? Or you spread it on the deck itself? I plan on doing the repair soon on my 5.7. Thinking of either trying the injection method, but really want to just cut the top skin off in the affected area put some cloth and epoxy back over the core and then put the skin back on. My area is a lot smaller than the OP. 30 inches seems long

My Gcat 5.7 had 4x 6" access ports allready installed. 2 in each hull about 1 foot behind each beam. I turned the hulls upside down and put them on sawhorses as high as possible then "painted" the inside of the hulls under the soft spots with the 2 part high density foam spreading the mixture as thinly as possible. My first try was too thick and expanded into about 3" of foam. I sanded it down. Thinner is better. I ended up with a layer about one inch thick which added almost no weight and now strongly supports what used to be a very soft deck. No prep required. The entire job took 20 mins.

This finished foam material is incredibly durable, light and strong. It is a closed cell foam meaning it will not soak up water like a sponge. I have found this to be a much better option than the traditional fiberglass repair for this application but if it was a structural repair I would still go with fiberglass or epoxy.

It all depends on the extent of the damage. Epoxy injection is a totally effective and legitimate repair process (even used to repair high end aerospace composites) as long as you're only repairing a small area and the foam core is not highly deteriorated. In essence, if you are able to identify the soft spot early on before it grows or the laminate (core material or inside fiberglass skin) are damaged, then injection is for sure the way to go.

If you wait too long and the inside glass skin cracks or the core starts to break down, then epoxy injection either won't work (the epoxy will leak into the hull) or will add a huge amount of weight (epoxy would need to fill the entire void where there was once foam). In that case, you would need to cut out the affected part of the hull and rebuild the structure.

Slathering expanding foam on the inside of the hull might be a quick short-term solution, but it's not a very controllable process so it may not hold up long-term, especially without having any glass reinforcement.

sm

bradinjax

They are foam core. I used an alternative solution to the traditional fiberglass repair that was simple, easy and effective on my G-Cat 5.7...

Actually, not all g-cats were foam cored
I asked Hanz last night and he confirmed this - he didn't elaborate past that

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I turned the boat upside down and spread 2-part high density foam

I am glad you are happy with the results, but ...

I would be very hesitant using any foam product as the basis of repair -
even if it is closed cell - can you be sure there will not be any condensation that forms inside it
I will leave it at that

this method also does nothing to address the actual problem (failing foamcore) that will continue to degrade with time if not addressed

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I have found this to be a much better option than the traditional fiberglass repair for this application but if it was a structural repair I would still go with fiberglass or epoxy.

I figured a soft deck was a structural issue. I figured that's why I have seen Hobie 16's with the hull broken off in front of the front cross beam, such a common place for delamination

With MN3’s post about Hanz saying yes and no to the deck composition, i am thinkg anout mounting
A couple of deck hatchs, probably mid hull inbetween the normal seated crew positions. That will allow me to
Determine the structure i am dealing with. Then look at the options.
1. If its straight glass, Attack it from underneath, resin and cloth, matting, then more cloth over the affected area
2. Foam core, the usual injection method, i can always add structure from the underneath if it still needs help.
2b, ??, has any one invererted a hull and tried perifry holes with center injection, plugging the outer holes as they start to drip? This would keep the liquid resin from draining into the lower hull and limit the amount injected
Or is that a case of over thinking the problem.

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82 GCAT 5.0
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A couple of deck hatchs, probably mid hull inbetween the normal seated crew positions. That will allow me to determine the structure i am dealing with

seems you could use Dogboy's method first, without cutting holes in your cat

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"I’m not sure how the G Cat hulls are constructed, but you could determine pretty easily if they are solid laminate or foam core by carefully drilling a small hole (like 1/8” diameter) into the deck. This will tell you right away if there is a foam core and therefore what type of repair method is appropriate."

Literally with an 1/8” drill you can answer the question and determine the hull construction without a doubt before yoh start hacking large holes in your boat.

sm

Two methods I used:

I repaired a relatively large soft deck (about 3 ft long) on my H18 using the epoxy injection method. I drew a grid pattern and drilled holes every 2 inches. I had small sections of clear packing tape precut and taped to the edge of the deck for quick retrieval. As soon as epoxy would start to emerge from the holes, I would cover them with the tape. Once all covered, here was the problem: It was a large enough amount of epoxy to generate a lot of heat. Inside the foam core, there was not much dissipation. The deck got hot. Real hot. I sorta stood back with a beer to see if it would burst into flames. In the end, I had some waves in the deck but it was rock solid. I sailed the boat for over 10 years with no issues, other than a couple of other smaller delam issues showing up. It seems once you have this issue, it can grow. I ended up replacing the hulls as I figured it was just getting too bad.

On my Prindle, I purchased it with some damage to the deck, where it was cracked in front of the deck ports right where you sit, and was flexing. I cut some carbon fiber cloth and 1/4 foam in a length as wide as the deck, and a width narrow enough to fit in the deck port. I figured I could use the outside curvature of the deck and make the panel on the outside first. I laid some polyethylene plastic on the deck, then some wetted carbon fiber cloth, then the foam, then another layer of wetted carbon fiber. Then a layer of polyethylene plastic, a thin section of sheet metal to cover it, some very short spacers of 2x4 precut to the right lengths and angles, then a 3/4 thick section of iron I keep around as an anvil to press it all together. Once cured, I had a foam core carbon fiber panel, exactly contoured to the deck. I spread thickened epoxy on it, lowered it into the deck port, affixed it inside of the deck, then put a precut 2x4 vertically to hold it in place. I tapped a small wedge between the 2x4 and the keel to snug it up. The deck is rock solid now. Note this was a smaller damage area than my first example.

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Bill Mattson
Prindle 19 "Gelli Bean"
Prindle 19 "Cat's Pajamas"
Nacra 5.2 (Will sail her a bit and let her name herself)
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Thanks for the input guys.
I’ll let you know how it works out.
Oh DONT rig your boat like I did in the photo.
Let’s just say it was an exciting couple of minutes putting it in the lake.

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82 GCAT 5.0
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Few things, The 5.0 is built differently than a 5.7. The drilling a hole idea may not work because the deck is solid glass and has two foam stringers that run the length of the deck. Depending on where you drill you may find foam or not. My experience with those decks are the foam that's in them will be full of water so there's no injecting them as a repair. They are not built like a Hobie so comparisons with them are out. Hans can't answer to any degree of certainty because the guys building his boats sometimes ad-libbed. I knew a guy that made a deck mold and changed both decks. That's probably not an option. Two ways to do this. Add glass to the top of the deck. A lot of work and you have to refinish the deck. Last option that I have done is cut a hole in the deck for a 6-inch port to get access. I made bulkheads that fit snug to the deck and hull. That gets glassed into the hull and deck and will make the decks good as new. You may need to add more than one considering the soft area is 30".

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Have Fun,
Mike
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Thanks.
2 stringers. thinking maybe with my luck I'd cut a port into the deck and find I had severed a stringer causing structural damage. Back to the inversion method. The boat has spent a lot of time out of the water High and dry.
I can try the drill and fill technique, maybe with variations.
invert the hulls, drill fore and aft then inject Methanol, its hydrophilic and will take any water that's there with it, that should help
dry out the foam, if it doesn't destroy it? Then after that has dried, a thinned resin to penetrate the fine fissures and cracked areas where the separation has occurred, followed by a thicker epoxy type resin for structure. Once it has set and cured for a few days try jumping on it, if its good, its good. If not I'll grab a saw and get busy on putting an access port in and then trying
building up reinforcing structure between the stringers, Resin udf matting then cloth depending on what seems
best once its opened up.
Any info on the size, placement and space between the stringers?
I have a SeeSnake I might try a 1/2 inch hole and do a little visual recon if the Drill and Drizzle doesn't work.
Mike thanks for the info!

Bob
87 Gcat
Personal record, 6 times horizontal in a day
I learn, it just takes a while



Edited by Dabblin on Apr 04, 2018 - 09:43 PM.

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82 GCAT 5.0
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Whether the foam stringers are good or not does not matter. The glass is damaged otherwise there would be no flex in it. So the goal is to support the deck another way. I made bulkheads using some 4mm foam, glass both sides then using a cardboard pattern I made trimmed the bulkhead to fit. It's a bit of work but I have fixed a few of those decks that way.

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Have Fun,
Mike
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