Spray Layup Repair

[David Cowen]

I am patching up some holes in my hull project but it seems to be a spray layup with a chopper gun. There are no defiined layers in the laminate that I can see apart from the gel coat. What is the recommended hand layup technique for this type of hull?

[Dutch Peter]

David,

i) Cut back damaged area to sound laminate
ii) Grind back the edges to a feather bevel (either single or double)
iii) Surrounding of the repair area to be cleaned, degreased and dried
iv) Fix and secure temporary backing panel over the hole (with release agent!!!)
v) Depending on which side you're working, apply a gelcoat resin untill touch dry
vi) Apply the layers of reinforcements untill the hole is flush, for a spray-up laminate I believe it's best to use CSM, resin can be either poly or epoxy, epoxy is better/more expensive
vii) Last layer(s) to extend well over the edges of repair area

In case of large repair, increase thickness with about 25% and add overlaminated 50x50 mm battens on the edges of the repair.

Good luck

[tja]

Weather it's sprayup or hand layup there is little difference. The important thing is to prepare the surface properly by grinding the afected area and hand layup the damaged areas with a General purpose polyester resin. That is what the boat is made of so I would use the same type resin. Taper in the layers. Don't make a fairly easy job dificult, keep it simple, Tom.

[gulfcoast crabb]

tja is right its simple keep it that way, grind the affected area back to good clean glass beveled away from the hole,make sure the area is clean and dry before you start the repair, wipe it down with acetone or another solvent. for a small area i would just use poylester resin and chop, the chop can be torn apart and used as a filler, build it up above the original layer of glass, then sand it down as neded.

[Aaron23]

Dutch Peter, you mentioned using epoxy resin for the repair over partially cured polyester gelcoat.

Is this ok to do? I'm constantly told that gelcoating a repair made with epoxy is a no-no, but will it work if done in the reverse order (I understand the bond will be mechanical)?

I am repairing 2" x 10" hole at the very bottom of the boat and I want to repair it from the outside in with epoxy using a mold as you mentioned, but I want the outside surface to be gelcoat.

Will this work? Any Suggestions?

I'm attaching a pictures of the hole prepped for the repair, maybe this will help the originator of this thread - anyone want to critique my work so far?

[Dutch Peter]

Dutch Peter, you mentioned using epoxy resin for the repair over partially cured polyester gelcoat.
Where did I say that?!


I understand that epoxy is bonding much better to poly than poly to poly. Poly to epoxy is the worst bonding.
Why not replace the gelcoat with epoxy filler at the repaired area, that why you have the smooth hull and no bonding problems!!

[Aaron23]

Can anyone recommend a specific epoxy product that I could use here?

[Dutch Peter]

Aaron,

As you are living in the US, try West Systems