Best Ways to Minimize Waste of Fiberglass and Foam

[CatBuilder]

Within a couple days, I will be at the point of glassing the first 1/3 of my hull. At least things are progressing now.

I am required by the designer to orient my single layer of 34oz (1150 g) triaxial from bow to stern. This is the layup I need to do.

The fiberglass roll is 50" (127cm) wide.

The foam I have laid up is 44" (112cm) wide.

The foam is arranged on the mold so that the foam begins at the centerline of the keel in the bilge area of the boat, as can be seen in the following picture:



****NOTE: See the batten farthest to the right in this picture? That is a straight line made by a laser. Everything else is a curve.

I am doing the first 1/3 of the layup before putting more foam in the mold, so I can reach everything. I will glass the foam that you see is up in the picture above.

Questions on how to save materials and minimize waste:

1) Do I try to extend the foam to 50" (127cm) so that I have a perfect fit of glass to foam?

or

2) Do I try to make one edge of the foam square to the laser lined batten and cut off the excess fiberglass that will hang over at the bow and stern?

or

3) Do I line up the fiberglass with the curve that defines the keel line and just glass along the foam that is already there in the picture (and will continue to the bow), cutting off the few centimeters that overhangs the foam?

I am just not sure how to minimize waste here. It seems option number 3 would minimize the waste best, but then when I lay the next piece of glass down next to that first, it won't line up... because the first pieces would be lined up with a curve, while the second piece would be lined up with a straight line.

How do you take square glass and most efficiently lay it up in a complex curve?

Also, how do you go from a curved layup (the bilge) to a straight layup (the laser line batten) and have the fore and aft lamination I have to do line up right?

[SamSam]

I would think it best if the foam was wider than the glass and then you wouldn't have to cut anything. Wet glass drooping over an abrupt edge tends to be effected by gravity and would lift off the foam a little and leave a sort of humped plane as opposed to flat on the foam. You do plan to lap the next layup over the first?

Also, you're going to have to trim the works along the keel line, right?

[CatBuilder]

Ok, I can't get epoxy on the foam that will not be laminated and it's downhill of the glass job, though. What about that factor?

I plan a 2" lap all along the seam, but the first layer is following the curve of the bilge, while the secondis a straight line. How do you deal with that?

Yes, all is cut at the keel join line to mate halves.

[SamSam]

Why can't you get epoxy on the other foam?

Why is the second layer following a straight line and not following the first layer?

Are the foam pieces bonded together on their edges?

[CatBuilder]

Thanks, Sam. I'll reply in green to your questions below...

Originally Posted by SamSam

Why can't you get epoxy on the other foam?


Well, the idea there was so I wouldn't have to sand all the dribbled epoxy and could start with fresh foam to bond to. I picked that idea up here from someone.

I planned to end at a hard edge of foam, then probably have to sand the edge of the foam for drips and spills, then bond (using bog) the new foam to the already glassed foam, continuing on like this.

Why is the second layer following a straight line and not following the first layer?

I don't know. That's my question. How do I lay this up?

The entire layup is one single layer of 34oz triaxial. The first sheet (50" wide) follows the curve of the bilge which has a sheer curve and the tight curve of the bilge in it. That makes a "c" shape to the long sheet of glass.

The hull/deck has a slight "c" shape to it in the opposite direction.

The topsides are just straight lines.

The orientation of the warp is fore and aft.

How do you arrange the square fiberglass on a very round and curvy hull form to both cover everything and have a good, strong layup?

Are the foam pieces bonded together on their edges?

Yes. All foam is bogged to all other foam to form a single piece of core for the entire hull. I inject a light (mostly microballoons, tiny bit of colloidal silica) bog into any cracks or gaps between foam and use bog to generally fair the foam where there are gouges before glassing. It is a single, solid piece of core, all bonded together.