Hull Core

[WastinAway]

I have a boat that has had the hull core removed. In getting ready to replace the core material I have read that a layer of mat should be added between the hull and core. And I have read that epoxying the core directly to the hull is OK. Any input on which way is best?

[paulk]

Have always heard that fiberglass is essentially bendy stuff, while epoxy is stiffer and more brittle. If you epoxy the core to the fiberglass, eventually the fiberglass is going to bend, and the stiff and brittle epoxy is going to crack--- putting you just about back to where you are now. We replaced sections of our delaminated and rotted out cabin top core with polyester resin, NOT epoxy, for this reason. With the same materials throughout, the whole thing bends together (when and if it does) and holds together.
Stick with it-- it will certainly stick to you!

[Jeff_H]

Actually, epoxy is far less brittle then polyester, and far less fatigue prone that polyester, which is why it is preferable for use with high modulus reinforcing fibers. With all due respect you really made a pretty big mistake by not using epoxy. Epoxy has exceedingly higher secondary bonding strength tp polyester when compared to polyester to polyester secondary bonds. Epoxy is also superior in bridging gaps and sealing out moisture. Epoxy is harder to sand and requires greater care in handling.

Jeff

[fishclan]

Many new boats are being made of epoxy. They are useing a new type of system to Infuse the fabric, rather than spray it. Epoxy also will not have the problem of osmotic blisters.

[MaryBeth]

Please look more into what you are doing. You have the right idea, with the matting and all, but there are big differences between the laminating epoxies (such as West Sytem) and a fiberglass resin (which is most likely what you need).

Best of Luck,
MaryBeth

[deseely]

You don''t want to use mat with epoxy. Mat has a binder in it that holds it together. The binder will disolve in polyester resin and allow the random strands in the mat to conform to the surface. Epoxy will not disolve the binder so the mat will not flow out to conform to the surface as well. It also will leave the mat a hazy white color as if it is not saturated. As you can probably guess I already made that mistake and had to call the fiberglass supplier to find out what I did wrong.