So, allow me to explain.
1. If you do not use breather film; the bag will probably close before the vacuum goes across the entire part.
2. If you do not use some sort of release film or peelply; the epoxy excesses will get on the breather fabric and stick to the part like a mutha.
So, the stack allows the vac to go all the way over the part and then allows the desired flow and release.
For fabrics, peelply is also used so the finish is more uniform and not requires tons of sanding.
GT23
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Re: GT23
So, allow me to explain more.
For laminating plywood together; the part will like to walk; so make sure to use pins. I like aluminum nails that I leave in the part, but find a way to pin it and plan to not get the pins out.
Normally, the work is done on a flat, sealed table. Then the bottom does not need to be plastic. Then bag tape is used.
For laminating a transom 5 layers thick; it is going to be a bit tricky to bag before gelation at one hour.
Your part is also going to be thick and the bag will tear easily (or can, that is) on the sharp wood edges, so the breather fabric will also cushion the bag from destruction, but be careful of sharps. You should have some bag tape and some vac bag plastic or at least some 6 mil plastic and bag tape to repair your bag. Sand the edges of the top piece in your stack.
For laminating plywood, precoat all surfaces to bond together with epoxy and allow them to go to gel. Then apply either 1/16" vee trowel of thickened resin to each side or 1/8" to one side. The thickening should be enough so the ridges of the thickened resin do not sag before you close the part.
I apologize, did not check the pump for variability. But you want to only pull 9-10/30 for parts laminating. More is hard on the bag and can drive the resins out of the glue joint.
Your stack should be
Bag
Glued up parts with pins
Peelply or release film
Breather media
Bag
A typical stack on a sealed table is
Part
Release film
Breather media
Bag
A table stack if you laminate the top of the part would be
Part
Glass
Peelply
Release film
Breather media
Bag
A table stack if you want a table finish
Waxed table
Glass
Part
Release film
Breather media
Bag
A table stack if you want a peeply finish and two sides glassed. (This is 95% my way)
Waxed table
Peelply taped with masking
Glass
Part
Glass
Peelply
Release film
Breather media
For laminating plywood together; the part will like to walk; so make sure to use pins. I like aluminum nails that I leave in the part, but find a way to pin it and plan to not get the pins out.
Normally, the work is done on a flat, sealed table. Then the bottom does not need to be plastic. Then bag tape is used.
For laminating a transom 5 layers thick; it is going to be a bit tricky to bag before gelation at one hour.
Your part is also going to be thick and the bag will tear easily (or can, that is) on the sharp wood edges, so the breather fabric will also cushion the bag from destruction, but be careful of sharps. You should have some bag tape and some vac bag plastic or at least some 6 mil plastic and bag tape to repair your bag. Sand the edges of the top piece in your stack.
For laminating plywood, precoat all surfaces to bond together with epoxy and allow them to go to gel. Then apply either 1/16" vee trowel of thickened resin to each side or 1/8" to one side. The thickening should be enough so the ridges of the thickened resin do not sag before you close the part.
I apologize, did not check the pump for variability. But you want to only pull 9-10/30 for parts laminating. More is hard on the bag and can drive the resins out of the glue joint.
Your stack should be
Bag
Glued up parts with pins
Peelply or release film
Breather media
Bag
A typical stack on a sealed table is
Part
Release film
Breather media
Bag
A table stack if you laminate the top of the part would be
Part
Glass
Peelply
Release film
Breather media
Bag
A table stack if you want a table finish
Waxed table
Glass
Part
Release film
Breather media
Bag
A table stack if you want a peeply finish and two sides glassed. (This is 95% my way)
Waxed table
Peelply taped with masking
Glass
Part
Glass
Peelply
Release film
Breather media
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Re: GT23
Peelply will work as a release, but the breather media is thick and becomes encrusted with resin and then the peelply is a bugger to remove from the part, so I always use release film.
The release film I use has pinholes on 10mm squares. This is to allow some excess resins to bleed off into the breather film, but it is not enough to create a bond..
I have an excess of the bleeder release and could mail you some unless Jeff sells it; then buy from him please. It is reusable unless you are careless and rip it off.
The release film I use has pinholes on 10mm squares. This is to allow some excess resins to bleed off into the breather film, but it is not enough to create a bond..
I have an excess of the bleeder release and could mail you some unless Jeff sells it; then buy from him please. It is reusable unless you are careless and rip it off.
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Re: GT23
Thank you so much for the guidance.
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Re: GT23
Let me know if you have more ?...
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Re: GT23
The vacuum pump you recommended was great. It is adjustable. I bought a 4x8 vacuum bag... Worked great for the bow transom (9mm x2).
The transom was harder. As you pointed out, it was gonna be hard to get so many layers prepared and stacked before gelation. So I did it in two steps: the first (12mm x 3sheets)
went well. I got a good lamination. When I added the other two sheets ( one 12mm plus one 9mm) a few days later, I could not get a good vacuum. Maybe 7-8lbs. Some caulking I'd used for a seal had dried, and I ran out of fresh. I live in a small town and it was Sunday. So I had to go with it. Still made a pretty fair lamination, I think (hope)...
So now I have:
All the forms/stringers/transoms set up in place on the strongback. I have both bottom panels and both side panels (each 3 sheets of plywood) completed---cut and butt-jointed together. One bottom panel is already laying loose atop the forms...
The next step is to stitch them together, and after that I have a question:
When I built the FS-14, I completed all of the fiberglassing "wet"---the wood was epoxied, the biaxial cloth applied to seams, and the bottom covered in cloth all in one session. I had a helper, and it was a job.
How can this possibly be done with such an ENORMOUS boat?! And some recommend TWO layers of cloth in planing versions of the boat! Glassing the whole 23-foot hull twice in one session? Dang!
Seems I'd have to do this in sections. Is that completely unwise? I plan to glass a section, say five feet of her bottom, let it cure, then sand the edge of that job and do another section, with a narrow overlap (1-2 inches)..... is this a workable plan?
The transom was harder. As you pointed out, it was gonna be hard to get so many layers prepared and stacked before gelation. So I did it in two steps: the first (12mm x 3sheets)
went well. I got a good lamination. When I added the other two sheets ( one 12mm plus one 9mm) a few days later, I could not get a good vacuum. Maybe 7-8lbs. Some caulking I'd used for a seal had dried, and I ran out of fresh. I live in a small town and it was Sunday. So I had to go with it. Still made a pretty fair lamination, I think (hope)...
So now I have:
All the forms/stringers/transoms set up in place on the strongback. I have both bottom panels and both side panels (each 3 sheets of plywood) completed---cut and butt-jointed together. One bottom panel is already laying loose atop the forms...
The next step is to stitch them together, and after that I have a question:
When I built the FS-14, I completed all of the fiberglassing "wet"---the wood was epoxied, the biaxial cloth applied to seams, and the bottom covered in cloth all in one session. I had a helper, and it was a job.
How can this possibly be done with such an ENORMOUS boat?! And some recommend TWO layers of cloth in planing versions of the boat! Glassing the whole 23-foot hull twice in one session? Dang!
Seems I'd have to do this in sections. Is that completely unwise? I plan to glass a section, say five feet of her bottom, let it cure, then sand the edge of that job and do another section, with a narrow overlap (1-2 inches)..... is this a workable plan?
Re: GT23
I built the LB22 w/o help so yeah, in sections, just like you wrote. Years later there are no delaminaations so I don't see much wrong with "wet on dry". Little bit of sanding and lay the next section on or stay inside the 24hr window and just proceed. I know a mechanical bond is not as strong as chemical one, but good enough is just that, good enough.
Dougster
Dougster
Re: GT23
I’m with Doug. I work almost exclusively alone and frequently do section work. Sometimes makes a little more work on the back end, but . . .
I work wet on wet as much as possible, but frequently work wet on “green”(as in within the 24 hour window, no sanding). Never had any issues.
If working in sections, I try to finish all the layers at once as much as possible. That means that, to continue, sanding is only needed on the overlaps, not the whole section.
Jbo
I work wet on wet as much as possible, but frequently work wet on “green”(as in within the 24 hour window, no sanding). Never had any issues.
If working in sections, I try to finish all the layers at once as much as possible. That means that, to continue, sanding is only needed on the overlaps, not the whole section.
Jbo
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Re: GT23
23' of hull is about 8 yards of glass, db600 or 18 oz is 12 pounds~1:1 epoxy is about 1.25 gallons..
The way to do it is to mix batches for top and bottom.
Weigh the glass and put 40% on the hull with a 3/8" paint roller. Use paint tray and stay out of sun, slow resin, everything is precut, marked 3 ways with sharpies.
It takes like 2 minutes to mix 40% batch, 10 minutes to wetroll the hull, 5 minutes to roll the glass off a 3" tube, then you hit it from the middle with a fin roller 6" wide, takes 5 minutes to get down, mix batch 2 all ready to go for the 60% amount, pour it out and use the paint roller to spread it quickly, then start to squeegee and fin roll it to final. 2+10+5+5+2 is 24 minutes or 30 if you are slow and then batch two you basically get about 60 minutes to finesse it.
I'd never section it.
A second way is to stay on the roll and final as you go. So, you mix smaller batches like 24 oz resin and wetout a smaller area, then offroll 3' at a time or whatever it takes to keep the roll on the boat. Then final 3' at a time. I did the entire top of the cabin this way. You just roll back to the wetted area enough to wet the substrate 40-50% and then roll another 3' to final..
The way to do it is to mix batches for top and bottom.
Weigh the glass and put 40% on the hull with a 3/8" paint roller. Use paint tray and stay out of sun, slow resin, everything is precut, marked 3 ways with sharpies.
It takes like 2 minutes to mix 40% batch, 10 minutes to wetroll the hull, 5 minutes to roll the glass off a 3" tube, then you hit it from the middle with a fin roller 6" wide, takes 5 minutes to get down, mix batch 2 all ready to go for the 60% amount, pour it out and use the paint roller to spread it quickly, then start to squeegee and fin roll it to final. 2+10+5+5+2 is 24 minutes or 30 if you are slow and then batch two you basically get about 60 minutes to finesse it.
I'd never section it.
A second way is to stay on the roll and final as you go. So, you mix smaller batches like 24 oz resin and wetout a smaller area, then offroll 3' at a time or whatever it takes to keep the roll on the boat. Then final 3' at a time. I did the entire top of the cabin this way. You just roll back to the wetted area enough to wet the substrate 40-50% and then roll another 3' to final..
Re: GT23
I’ve also done FallGuy’s second suggestion.
I can think and plan through the first suggestion, but could never pull it off in reality. LOL. Maybe I just lack the confidence. I did make a screen-shot so I could keep it in mind to try if I get up the nerve.
Jbo
I can think and plan through the first suggestion, but could never pull it off in reality. LOL. Maybe I just lack the confidence. I did make a screen-shot so I could keep it in mind to try if I get up the nerve.
Jbo
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