Proper fiberglass techniques

[florida196]

I've seen mixed reviews but when overlapping your layers of fiberglass whether it's mat or biaxel or so on.  Is it better for your first layer to be longest then shorten layers after that.   Or should your last layer be the longest

[seabob4]

You want to have the 1st layer the "shortest".  There is no use in adding subsequent layers if all they are bonding to is the 1st layer of glass...

[RickK]

I've also read where some guys will always lay the widest tabbing first and work there way down to the narrowest.  They say it doesn't matter in the end result strength wise when laying it all wet on wet.
I think that laying the narrow tab first just makes better sense.

[florida196]

We'll that's not good if I've been doing it backwards.  Everything I've done tabbing wise is widest first such as 12" then a 6" on top of that one most has been wet on wet.

[RickK]

Not sure it really matters - some people say that for bridging the fillets on edges is easier doing it in the process you are doing. I guess it's google time.
Wet on wet they all become one in the end anyway.

[Georgie]

Don't fret at all... another school of thought is this:  When done, you undoubtedly, inevitably, and invariably have to do some grinding.  Why not make sure the largest (and strongest) layer in your cloth sandwich is the first one at the bottom of your lamination and the smallest piece is at the top so that you minimize how much of the long, continuous laminate you grind back out of the job.  I struggled with this same issue for a long time and I've done repairs both ways.  Either will work, but ultimately I think I'd rather  be grinding small glass filler pieces off the top rather than the largest sheet of glass that provides the most structural benefit.   Just another perspective to ponder.  

[Aquasport Commodore]

Don't fret at all... another school of thought is this:  When done, you undoubtedly, inevitably, and invariably have to do some grinding.  Why not make sure the largest (and strongest) layer in your cloth sandwich is the first one at the bottom of your lamination and the smallest piece is at the top so that you minimize how much of the long, continuous laminate you grind back out of the job.  I struggled with this same issue for a long time and I've done repairs both ways.  Either will work, but ultimately I think I'd rather  be grinding small glass filler pieces off the top rather than the largest sheet of glass that provides the most structural benefit.   Just another perspective to ponder.  

[kaptainkoz]

If every layer we laid went on pin straight without a fold, dimple or lift I would say it wouldn't matter either way. However I agree that the largest layer first may be the way to go. You will get the largest actual surface area bond. Now if folds and lifts create in the next layers, theoretically it's smaller pieces that are less critical to the strength of the overall bond. To exaggerate the point, let's say you laid the first layer of fiberglass on a super flat surface, then you dropped a pea or a ball bearing on it and applied the next layer. That 2nd layer will "tent" over the pea and not have a great bond at that spot. Same holds true with each layer we add as they get lumpy from the prior layer.
Yes, it's splitting hairs and either method will work fine but that's my 2 cents. Initial surface preparation is A1, king of importance to a good bond no matter which layer schedule you adopt.

[Shine]

I've seen mixed reviews but when overlapping your layers of fiberglass whether it's mat or biaxel or so on.  Is it better for your first layer to be longest then shorten layers after that.   Or should your last layer be the longest

I asked that question to a composites expert from the USN Academy at an IBEX seminar about 8 years ago ....

With poly or vinylester resins, your wider tabbing needs to overlap previous narrow layers.  With epoxy it actually does not matter. 

[fitz73222]

This is not my field of expertise by any means but I've done enough fiberglassing to know that the last tab should be the longest because it ensures each tab layer beneath is bonded to the hull. If the longest tab layer was first, followed by shorter tabs then the only bond layer to the hull is the longest one so if it were to fail, all of the other layers on top of it become inconsequential since they're not attached to the hull directly. 

[RickK]

I think with epoxy they all become one piece in the end so it doesn't matter.  I think for poly you are thinking correctly Farley.