DaveH6
A fiberglassed pilot house top...I think
Fiberglass was applied to protect the marine plywood from the elements since Okoume has little resistance to rot. First, I glued on full length strips of wood to the port/starboard and aft edge(s) . These strips were carefully sanded and worked to ensure I had square edges and fair cures especially on the side edges. I didn't put a strip on the front edge as it was cut very cleanly by the router attached to a pivoting arm. Screw holes from the top sheet temporary clamping process were filled and the entire top was sanded. I continue my practice of working plywood structures to create a fair surface. My hope is that after fiberglass or Xynole is applied I only have to fill the fabric's texture and then the job is done as there should be no high or low spots in the underlying structure.
So, I positioned the two 6' wide pieces of 6oz fiberglass on the top with the seam running port to starboard across the 7' width for easier access in fairing. I then trimmed the glass to a rough dimension. The fiberglass was removed and next I squeeged on a thin coat of Raka epoxy. I forced the epoxy into the plywood and let it cure for a brief period. The expectation is that the wood is somewhat sealed and the epoxy is applied too thin for air filled bubbles to form from warming wood. Hopefully this thin epoxy coat will later reduce the plywood from sucking the epoxy out of the fiberglass. I then put the fiberglass back in place and smoothed it out which was easy to do with its 6oz weight.
I squeeged epoxy into the fiberglass weave which saturated the fiberglass so easily and I didn't have to cut darts in the corners to wrap the edges. With the epoxy applied, I standback and admire my work and think I'm getting quite good at this boatbuilding stuff and perhaps need elevation from my self proclaimed status as a "novice" boatbuilder.
I continue to check the epoxy for tackiness so I can apply a coat of unthickened epoxy to flood the fiberglass weave. The epoxy is not getting tacky and I notice that it seems to have an unusually thin viscosity. Oh well, it is rather cool that day and severe thunderstorms are in the area thus I conclude the temperature and perhaps dampness are impeding the epoxy kicking off.
Three hours later I conclude something is not right and I start thinking through what is going on. I glance at the part A and part B Raka epoxy jugs. After applying the thin sealing coat of epoxy, in haste I brought two jugs from the workshop to the garage to be near the top when flooding the fiberglass. One jug is yellow which means hardener and one jug is white or clear which means resin. I turn the "resin" jug around so the label is visible and the mystery is solved.
For the first time, I notice that the Raka 610 Fast hardener is a light yellow color instead of the more pronounced yellow colors of other Raka hardeners. I laminated on the fiberglass by mixing together 610 fast and 350 non-blush hardeners and no resin. I had just committed the biggest mistake in my four years of boat building. Prior to this mistake, I had sucessfully mixed over 30 gallons of epoxy. When I was pumping the fast hardener thinking it was resin, I noticed how easily it pumped thus this should should have set off alarms and investigation. I screwed up big time on this near 7' by 11' structure.
After the perfunctory string of creative profanity, I calmed down and considered two courses of action. 1.) pull off and trash the fiberglass and clean the hardener residue with warm water which I understand will remove hardener and start all over again or 2.) apply resin only to the fiberglass and vigorously work it with a squeege into the hardener saturated fiberglass. I choose the later course and found that the epoxy quickly started getting tacky (after all I was using a fast hardener) and after letting it harden further, the fiberglass appeared somewhat bonded to the plywood. Had the fiberglass been heavier than 6oz I wouldn't have attempted to "mix" in resin via a squeegee. Next, I flooded the fiberglass with a properly mixed coat of un-thickened epoxy to fill the weave. . I must admit that the curiosity of whether the epoxy could be saved was the primary driver of my repair strategy.
A day later the roof has a hard epoxy coating that appears normal though I can't attest to what is going on under this thin top coat. Some of the glass that is wrapped around the edges is still squishy as I suspect I didn't force enough resin into the hardener laden glass during my repair. Today's 62 degree temps are not conducive to determining whether additional curing time will toughen these edges.
Certainly the epoxy in my repair is not mixed to its prescribed 2:1 ratio thus I suspect that the epoxy will not obtain its rated strength. However, a future failure with this epoxy on the roof top will be a non-structural issue assuming I repair before water reaches the plywood. No use asking for advice on the longevity of my repair as I assume that nobody, but nobody in the history of the world has matched my carelessness and replicated my squeegee epoxy mixing strategy. Tonight I expect a call from Darwin.
In the absence of conclusive evidence that the fiberglass will delaminate, I will eventually apply a very thin coating of fairing compound, sand, repeat if necessary and then spray a 2 part epoxy primer and then Awlcraft 2000 paint.
I have abandoned my thought of removing the title "novice" from my boat building resume.
***Edit 04/08/2013- After letting the epoxy cure for four days, I dug through the top coat of cured epoxy and tested a 2"x2" area of the 6oz fiberglass for adhesion to the plywood. It wasn't adhering nor was the rest of the glass. With ease, I ripped the entire 7'x11' fiberglass sheet off. The residue is a sticky goo that has wicked into the plywood. Progress being made with chemicals, scrapers and sanders in my quest to get back to bare plywood. Once there, I will start over again assuming my brain isn't permanently atrophied from the clean up.
Don't screw up epoxy mixing as doing so is like breaking a mirror ....there is no repair.
.
A fiberglassed pilot house top...I think
Fiberglass was applied to protect the marine plywood from the elements since Okoume has little resistance to rot. First, I glued on full length strips of wood to the port/starboard and aft edge(s) . These strips were carefully sanded and worked to ensure I had square edges and fair cures especially on the side edges. I didn't put a strip on the front edge as it was cut very cleanly by the router attached to a pivoting arm. Screw holes from the top sheet temporary clamping process were filled and the entire top was sanded. I continue my practice of working plywood structures to create a fair surface. My hope is that after fiberglass or Xynole is applied I only have to fill the fabric's texture and then the job is done as there should be no high or low spots in the underlying structure.
So, I positioned the two 6' wide pieces of 6oz fiberglass on the top with the seam running port to starboard across the 7' width for easier access in fairing. I then trimmed the glass to a rough dimension. The fiberglass was removed and next I squeeged on a thin coat of Raka epoxy. I forced the epoxy into the plywood and let it cure for a brief period. The expectation is that the wood is somewhat sealed and the epoxy is applied too thin for air filled bubbles to form from warming wood. Hopefully this thin epoxy coat will later reduce the plywood from sucking the epoxy out of the fiberglass. I then put the fiberglass back in place and smoothed it out which was easy to do with its 6oz weight.
I squeeged epoxy into the fiberglass weave which saturated the fiberglass so easily and I didn't have to cut darts in the corners to wrap the edges. With the epoxy applied, I standback and admire my work and think I'm getting quite good at this boatbuilding stuff and perhaps need elevation from my self proclaimed status as a "novice" boatbuilder.
I continue to check the epoxy for tackiness so I can apply a coat of unthickened epoxy to flood the fiberglass weave. The epoxy is not getting tacky and I notice that it seems to have an unusually thin viscosity. Oh well, it is rather cool that day and severe thunderstorms are in the area thus I conclude the temperature and perhaps dampness are impeding the epoxy kicking off.
Three hours later I conclude something is not right and I start thinking through what is going on. I glance at the part A and part B Raka epoxy jugs. After applying the thin sealing coat of epoxy, in haste I brought two jugs from the workshop to the garage to be near the top when flooding the fiberglass. One jug is yellow which means hardener and one jug is white or clear which means resin. I turn the "resin" jug around so the label is visible and the mystery is solved.
For the first time, I notice that the Raka 610 Fast hardener is a light yellow color instead of the more pronounced yellow colors of other Raka hardeners. I laminated on the fiberglass by mixing together 610 fast and 350 non-blush hardeners and no resin. I had just committed the biggest mistake in my four years of boat building. Prior to this mistake, I had sucessfully mixed over 30 gallons of epoxy. When I was pumping the fast hardener thinking it was resin, I noticed how easily it pumped thus this should should have set off alarms and investigation. I screwed up big time on this near 7' by 11' structure.
After the perfunctory string of creative profanity, I calmed down and considered two courses of action. 1.) pull off and trash the fiberglass and clean the hardener residue with warm water which I understand will remove hardener and start all over again or 2.) apply resin only to the fiberglass and vigorously work it with a squeege into the hardener saturated fiberglass. I choose the later course and found that the epoxy quickly started getting tacky (after all I was using a fast hardener) and after letting it harden further, the fiberglass appeared somewhat bonded to the plywood. Had the fiberglass been heavier than 6oz I wouldn't have attempted to "mix" in resin via a squeegee. Next, I flooded the fiberglass with a properly mixed coat of un-thickened epoxy to fill the weave. . I must admit that the curiosity of whether the epoxy could be saved was the primary driver of my repair strategy.
A day later the roof has a hard epoxy coating that appears normal though I can't attest to what is going on under this thin top coat. Some of the glass that is wrapped around the edges is still squishy as I suspect I didn't force enough resin into the hardener laden glass during my repair. Today's 62 degree temps are not conducive to determining whether additional curing time will toughen these edges.
Certainly the epoxy in my repair is not mixed to its prescribed 2:1 ratio thus I suspect that the epoxy will not obtain its rated strength. However, a future failure with this epoxy on the roof top will be a non-structural issue assuming I repair before water reaches the plywood. No use asking for advice on the longevity of my repair as I assume that nobody, but nobody in the history of the world has matched my carelessness and replicated my squeegee epoxy mixing strategy. Tonight I expect a call from Darwin.
In the absence of conclusive evidence that the fiberglass will delaminate, I will eventually apply a very thin coating of fairing compound, sand, repeat if necessary and then spray a 2 part epoxy primer and then Awlcraft 2000 paint.
I have abandoned my thought of removing the title "novice" from my boat building resume.
***Edit 04/08/2013- After letting the epoxy cure for four days, I dug through the top coat of cured epoxy and tested a 2"x2" area of the 6oz fiberglass for adhesion to the plywood. It wasn't adhering nor was the rest of the glass. With ease, I ripped the entire 7'x11' fiberglass sheet off. The residue is a sticky goo that has wicked into the plywood. Progress being made with chemicals, scrapers and sanders in my quest to get back to bare plywood. Once there, I will start over again assuming my brain isn't permanently atrophied from the clean up.
Don't screw up epoxy mixing as doing so is like breaking a mirror ....there is no repair.
.