Foam repair to soft deck-spots

Hi!

I am planning to repair some soft spots in the deck by injecting foam in between the layers. I think that this is the best method that does not add extra weight to the hull.
Have others experience with this? I am thinking of using Urethane pour foam and use a syringe to inject it in between the layers, with additional holes, through which the extra foam can escape.
If people know a good method and a good product, please let me know!

G.
 
Thank you LooserLu.

The method is pretty much what I was planning to do, except instead of using epoxy resin I want to use foam. I am a bit worried about the weight of the resin. The article states that you will need "8 pumps of epoxy and resin for a 6" diameter area." That adds up quickly when you have to treat several of these spots. I think a good quality Urethane foam should be strong enough to re-inforce the deck without adding much weight to the hull...
 
So, in case anyone is interested, this is what I did to repair two rather big soft spots on my deck (on each side where one mostly sits).

1. put masking tape on the whole area and mark the area.
2. drill small holes about two to three inches apart in the whole area (just through the top-layer of course). I used the size of drill that creates a hole so small that I could barely fit the tip of a syringe into the hole.
3. cut off a syringe and put it at as an extension on a can of spray-foam (sealant for insulation and filling up cracks). Try if it works before using it on the boat. The foam will become liquid again when it floats through the small opening that you attached to the can. I did not find it hard to create a non-leaking connection.
4. inject the foam slowly through the holes in the hull (where the two parts were delaminated) stop when you see it coming out another hole, and continue with the next hole. work from one side to the other.
5. as the foam expands it will come out of the holes again, hence the masking take.
6. put some weight on the spots that are not level with the rest.
7. after 24 hours, clean up, redrill the holes just a tiny bit, and fill them up with Marine Tex (or gelcoat). Again clean-up could be reduced by using masking tape before applying Marine Tex.

I am really happy with the result! The deck is solid (no soft spots at all) and although I did not actually weigh the hull, the weight cannot be increased by any significant amount, since the foam barely weighs anything (if I had used epoxy, the weight would have increased much more). Also the foam is really cheap ($5).
Time will tell how long it will hold. The foam seals permanently to many different materials (including your hands; latex gloves are adviced!). Mostly, it thus seals again the foam-like layer and the top fiberglass layer that in previous times created a firm deck. The foam does have some flexibility, which is not bad either, as it will not crack as easy as a hard layer. Thus I have good hopes!

GWF
 
So, in case anyone is interested, this is what I did to repair two rather big soft spots on my deck (on each side where one mostly sits).

1. put masking tape on the whole area and mark the area.
2. drill small holes about two to three inches apart in the whole area (just through the top-layer of course). I used the size of drill that creates a hole so small that I could barely fit the tip of a syringe into the hole.
3. cut off a syringe and put it at as an extension on a can of spray-foam (sealant for insulation and filling up cracks). Try if it works before using it on the boat. The foam will become liquid again when it floats through the small opening that you attached to the can. I did not find it hard to create a non-leaking connection.
4. inject the foam slowly through the holes in the hull (where the two parts were delaminated) stop when you see it coming out another hole, and continue with the next hole. work from one side to the other.
5. as the foam expands it will come out of the holes again, hence the masking take.
6. put some weight on the spots that are not level with the rest.
7. after 24 hours, clean up, redrill the holes just a tiny bit, and fill them up with Marine Tex (or gelcoat). Again clean-up could be reduced by using masking tape before applying Marine Tex.

I am really happy with the result! The deck is solid (no soft spots at all) and although I did not actually weigh the hull, the weight cannot be increased by any significant amount, since the foam barely weighs anything (if I had used epoxy, the weight would have increased much more). Also the foam is really cheap ($5).
Time will tell how long it will hold. The foam seals permanently to many different materials (including your hands; latex gloves are adviced!). Mostly, it thus seals again the foam-like layer and the top fiberglass layer that in previous times created a firm deck. The foam does have some flexibility, which is not bad either, as it will not crack as easy as a hard layer. Thus I have good hopes!

GWF
George,
It looks like its been a few years since this repair.. how did it hold up? I need to fix a soft spot and was thinking about using your method.
 

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