Bondo

[Joey@HAT]

Anyone use bondo for hardening a soft spot/joining marine plywood together. I'm re-coring my deck. The west system is getting expensive. Don't want the bondo for exterior of the finish just he inside.

 

[jbcurt00]

Its not likely to be a good substrate, IIRC its got talc as a filler, not good in a marine environment

 

[ondarvr]

What exactly do you want to do with it? There's no need for a West Syatems product if you're trying to save money, but Bondo is at the other end of the quality scale.

 

[Ned L]

Anyone use bondo for hardening a soft spot

Uhm,..... Once plywood has started to rot (go soft), soaking it with something ( epoxy, whatever) really does not bring back the strength.

 

[Woodonglass]

Some other things to consider...Bondo resin does NOT adhere to epoxy and it requires you to lay down Chopped Strand Mat. You can't just use the resin by itself like you can with epoxy.

 

[Joey@HAT]

I used the west system and added filler into the resin. I drilled holes into the foredeck. I added the mixture into the empty chalk tubes and shot it in the deck. Its as hard as a rock now. I wanted to know if I could do the same with Bondo

 

[jbcurt00]

Caulk tubes?

So you're asking about Bondo brand polyester resin, not Bondo the body filler? Originally, I thought you wanted to use the body filler, which isnt a good choice because of the talc as filler. Its also a polyester based product.

You pushed West System epoxy thru a hole drilled in a deck that has a rotten core material?

But only into the cavity between the 2 exterior layers of a cored deck?

Correct?

Bondo resin isnt a good substitute for epoxy. And I wouldnt count on the epoxy repairs you've already made being a long term solution. I doubt you removed all the effected core, and if theres any of it left behind, the problem will only migrate away from the areas you've filled w epoxy.

 

[ondarvr]

Short term it will sort of work, long term it will fail. Some people use a very high density two part foam to fill stuff like this, again, it appears good at first, but may not hold up for long.

 

[Joey@HAT]

Yes the bondo resin Not the auto filler. I used the high density foam first then used the west system. The person who own the boat before me, added 4 dingy holders. Never caulked the screw holes. Now I have the soft spots. I really should cut it all out. MY friend cut his out and added that hard plastic board. It can be soaked in water and never loss its strength. Then added resin and fiberglass. It came out strong and looks good.

 

[Ned L]

"Strong" can be relative and deceptive. I'm not particularly about your methods, but to each his own.

 

[Joey@HAT]

It PVC board that he used instead of marine plywood.

 

[Joey@HAT]

"Strong" can be relative and deceptive. I'm not particularly about your methods, but to each his own.

How would you go about fixing the soft spots?

 

[mjf55]

deleted

 

[Ned L]

Plywood that has begun to deteriorate (to the point that it has last strength) really needs to be replaced. 'Infusing' soft plywood with an epoxy or resin will make it hard, but it will alsp be brittle and may will crack internally rather than flex.

 

[DeepBlue2010]

IMO, any attempt to resurrect wood from the rot by injecting it with resin (epoxy or otherwise) is short lived for two reasons; First, rot is a bacterial infection not unlike the ones we - humans - get. Left untreated, it will take over, poison and kill. Second, resins are not designed to function on their own. The strong plastic composite is the result of mixing resins with glass. resins by themselves with never get close to the strength.

Post pictures of what r u working with so we can see what u see.

 

[Joey@HAT]

IMO, any attempt to resurrect wood from the rot by injecting it with resin (epoxy or otherwise) is short lived for two reasons; First, rot is a bacterial infection not unlike the ones we - humans - get. Left untreated, it will take over, poison and kill. Second, resins are not designed to function on their own. The strong plastic composite is the result of mixing resins with glass. resins by themselves with never get close to the strength.

Post pictures of what r u working with so we can see what u see.

I am mixing the resin with high density 405. Its harder then a rock once dried. What thickness of plywood did they use in 1967? ITs a 41 Hatteras.

 

[samt]

My first go at fiberglassing was a Meyers Manx dune buggy someone had really screwed up. I got a short lesson from the PO. Anyway he showed me how to fill holes with resin and glass cells mixed. So I filled the holes and tried to use it to fill some access plates someone cut. I backed it and then filled with resin and cells. Anyways like someone said it gets rock hard and extremely brittle. I never knew it was an issue until after my first go of paint!

But on my old boat I used bondo fiberglass resin and some light mat (lots of layers) to rebuild my stringers and I never had an issue. It was pretty dirty too. I don't think there is anything wrong with using bondo brand resin, just keep in mind it's not as strong as the epoxy resin so don't skim any. I buy mine off amazon if you look around you can get it super cheap. I think last I ordered was $34/gallon delivered.
One big advantage to the west system and other marine epoxys is the calibrated pumps. I have mixed a ton of resin and still get hot and cold batches using the bondo stuff.

 

[DeepBlue2010]

I am mixing the resin with high density 405. Its harder then a rock once dried. What thickness of plywood did they use in 1967? ITs a 41 Hatteras.

"Harder than a rock" doesn't mean strong. As it is the case with some metals even, it means brittle and some other elements need to be added to form a stronger and more fracture resistance alloy. This is what you get when you use resin without the glass. But, it is your boat and your call; do what you will.

I am not sure about the thickness of your plywood

 

[Joey@HAT]

No Title

I cut the deck and added marine plywood