Sebastian carnage

[freeride4me]

Well,I'm finally got around to investigating the fiberglass ripping off the bottom and it wasn't pretty!

I used West Systems epoxy resin & I think 8 oz glass to do the repair & skinned the entire bottom doubling up over the repair.

It seemed to fracture and then peel away. With a rigid scraper and a little effort it all separated from the SMC bottom including the repair. As far as I know my prep was done right ,but the SMC is like the particle board of fiberglass!

REPAIRING SMC SUCKS!!

Any similar stories or help appreciated
Oh yeah, I don't think the half a$$ BR's help either

 

[Speleopower]

Epoxy doesn't cure over polyester resin quite right. What are the hulls? polyester/glass cloth or epoxy/glass cloth?
Did you clean the surface really well? Did the West Systems get mixed correctly? Did it cure to fast? Did you have weights to press the cloth down with while curing?
Scott

 

[Matt_E]

Epoxy doesn't cure over polyester resin quite right. What are the hulls? polyester/glass cloth or epoxy/glass cloth?
Did you clean the surface really well? Did the West Systems get mixed correctly? Did it cure to fast? Did you have weights to press the cloth down with while curing?
Scott

The hulls are SMC (sheet molded compound)

Epoxy should work fine with it.

 

[keefer]

Yep, I have seen massive holes and gashes fixed with West systems epoxy and lots of fiberglass on several boat bottoms around here. All have held up for years with no delamination. Were the mating surfaces completely dry and clean from salt, oil, etc. Also was all of the cracked or loose SMC ground away to expose clean stable material?

 

[tor*p*do]

looks like a surface prep problem
could have been temperature as well; in other words was resin too hot/fast for conditions
this foothold tray reinforcement went wrong was due to surface prep and temp problems, I believe. but it may have been bad cloth:02:
peeled off easily.

 

[freeride4me]

Epoxy doesn't cure over polyester resin quite right. What are the hulls? polyester/glass cloth or epoxy/glass cloth?
Did you clean the surface really well? Did the West Systems get mixed correctly? Did it cure to fast? Did you have weights to press the cloth down with while curing?
Scott

from what I understand SMC is polyester resin base compound squished with a 50 ton press & heat(with mold release throughout the entire compound--which is why they paint the bottom instead of using gelcoat). So as you grind into it you get fresh release .:dunnoon't know if its true.

I didn't use any filler in the resin & used the proper ratios(w/pumps). The one thing I was probably guilty of was not getting all of the stock paint off the bottom. Guess what, the resin & glass bonded to the paint patches (evident in that there are no paint patches left behind )better than the roughed SMC.

 

[FL-cracker]

Dont use Poleyester on the SMC bottom whatever you do!

West systems is good!

My guess would be that it was not prepped correctly.

1.Make sure all paint is sanded off.

2.Use 36-50 grit to realy scuff up the bonding surface! Go across all the area with frest paper in a criss cross formation.... just smacking acrossthe bonding area, to were it leaves some big scratches... kinda hard to explain. lol

 

[freeride4me]

Dont use Poleyester on the SMC bottom whatever you do!

West systems is good!

My guess would be that it was not prepped correctly.

1.Make sure all paint is sanded off.

2.Use 36-50 grit to realy scuff up the bonding surface! Go across all the area with frest paper in a criss cross formation.... just smacking acrossthe bonding area, to were it leaves some big scratches... kinda hard to explain. lol

I didn't use poly,I did scratch it up good, & when it did pull off it pulled off the slightest layer of SMC. My comment about the paint was that it held stronger to the paint patches than it did to the SMC.

BTW it has taken about 30 hrs of hard riding over the last 6 months for this failure to happen.:barrel:& stepping up BR attemps!

Thanks for the input.

 

[Tuttle]

My comment about the paint was that it held stronger to the paint patches than it did to the SMC.

Paint must gave from the SMC then :1244:

 

[tom21]

is that the same prob pat was having? the smc is like particle board that got wet- its all flakey and easily scraped off? I know you know what you are doing, but if that smc is waterlogged and crappy it may keep delaminating right? just grind it all away and bond to the west system inside.:theyareontome:

 

[Matt_E]

Grind till you see motor mounts. :haha:

 

[douglee25]

It's definitely the paint. It needs to be grounded down all the way to the material before doing any sort of patch.

Doug

 

[Speleopower]

West Systems epoxy should work fine. Use the slow cure hardener, grind more of the old stuff back than you would expect down to undisturbed material. Get rid of all loose material, clean very very well and start adding cloth starting with the actual gash. If you can get into the hull and do the repair from the inside it would probably be better. That way you can add more weight on to the patch. Don't let the epoxy cure before adding another layer of cloth. Then put as much weight on top of the cloth as you can using a layer of wax paper or something similar between the weights and the glass patch.
When I glass a small foam radio control airplane wing I sometimes put 100 plus pounds of weights on the wing to get a good strong bond. Or I'll use a vacum bag system and put as much vacum as I think the structure will handle.
Scott