Polyester resin vs. Epoxy resin

[jj2003]

I'm building a 59" Outerlimits from central hobbies in twin drives. It will be on the heavy side so I need to beef it up a bit. It's made of polyester resin and fiberglass. I have heard that depending on what the hull is made of, you should use the same type of resin if strengthening the hull with carbon fiber or adding some reinforcements. What do any of you recommend or use in this situation? I've posted this question on a few sites to take an overall consensus.

[Fella1340]

i know this proves true in full size boats as well as fiberglass car pannels that epoxy over polyester is the way to go for best strength. I've seen it used ac cobra polyester car bodies where a lot of straightening was required to turn it into a high end show car, corvette body panels and just about every marine repair i have been a part of. plus the epixy doesnt stink! Never polyester over epoxyglass though. I would use epoxy and never look back! I didnt realize they were using polyester, i guess its a lot cheaoer. All that said you xan save yourself money and finish with polyester. Just have to make sure you really got things ckean and scuffed obce you go mounting things.

[jj2003]

i know this proves true in full size boats as well as fiberglass car pannels that epoxy over polyester is the way to go for best strength. I've seen it used ac cobra polyester car bodies where a lot of straightening was required to turn it into a high end show car, corvette body panels and just about every marine repair i have been a part of. plus the epixy doesnt stink! Never polyester over epoxyglass though. I would use epoxy and never look back! I didnt realize they were using polyester, i guess its a lot cheaoer. All that said you xan save yourself money and finish with polyester. Just have to make sure you really got things ckean and scuffed obce you go mounting things.

Thanks for the hands on info Fella :tiphat:. Thats good to know! So far the consensus is epoxy over poly. Clean, clean, clean is what I'm told so far so I'll be rough sanding with 80 grit and then blowing out with compressed air. Seems also that a cleaning agent is not recommended due to residue left behind unless someone knows of a really good product that wont effect the epoxy cure due to a petroleum agent.

[grsboats]

I've been doing this job on lot of poliester parts (full size boats,cars and bikes) using only epoxy resin from west System or Huntsmann and the results are great and better than with poliester.Yes you will need to sand carefully to ensure mechanical bond despite top grade epoxy resins present good chemical bonding but this is my personal experience so as Fella pointed out you can also stick to the same base resin with good strenght.Gill