Question for the tech heads ,
For a wetted out on table then squeegeed onto the board ( without vaccing )......
Q 1 : is two layers of 4oz wetted together stronger than one layer 8oz ?
Q 2 : how much stronger and heavier would two layers of 4 oz , done one after the other after curing be compared to one layer 8 oz ?
Strength is one thing , stiffness and ability to resist weight compression and dings is another .
All thoughts appreciated 
2x 4oz is stronger as it has less resin.
Over-resined is weaker and heavier.... double whammy.
You will sometimes see single 6oz on a surfboard, but only as 2oz glass is a lot more expensive than 4 or 6. Cluey customer would demand 4+2 instead....
4oz applied after the first layer of 4oz has cured is heavier and weaker also as you have to sand it to get a good bond.
More important though is using s-glass if you want strength.
As to wetout then applied but with no vac you might be in danger territory here. There will not be as much glass/resin to foam contact as with vac.
I might be wrong but I suspect it could be prone to delam and weaker.
Wetout, laid on and vac - yes.
Or, roll out on board dry and wet out on board...... unless its styro which will take up (soak) quite a bit more resin then PU or corecell.
So whats under the glass?
Q1 - Two layers would be stronger and stiffer. Maybe slightly heavier or may not be, depending on how you wet it out. One factor would be if the finer 4oz needs less filler coat to smooth the weave roughness. Courser 8oz would probably hold more to fill.
Q2 - Two 4oz layers doing second after cure I think would definitely be heavier, and possibly not as strong. Maybe slightly stiffer though with a layer of resin between the layers. Not so sure about this one.
With Vac and ideal resin to glass ratio, the two layer would definitly be stronger I recon.
Definitely use multiple light layers and do it in one operation.
Lighter and stronger.
You really do want to get a vac setup, it makes a much lighter, stronger laminate.
Light and strong and because it's well compacted, it's amazing how little fabric you can get away with.
I cover my wet laminate with one final layer of 48gr glass and this is applied dry and then into the vac bag.
It does an absorber job and always comes out of the vac bag fully impregnated.
You need to be using vac to do this type of layup.
old school method is 2 layers 6 oz on the deck and i layer 6 on the bottom.
delam is a vac bag legacy.
Select to expand quoteImax1 said..
Question for the tech heads ,
For a wetted out on table then squeegeed onto the board ( without vaccing )......
Q 1 : is two layers of 4oz wetted together stronger than one layer 8oz ?
Q 2 : how much stronger and heavier would two layers of 4 oz , done one after the other after curing be compared to one layer 8 oz ?
Strength is one thing , stiffness and ability to resist weight compression and dings is another .
All thoughts appreciated
I think for such a thin layer on a board the difference in strength would be so miniscule that it wouldn't matter.
So my layup schedule for my 12ft boat is 2 x 6oz Biax Ioverlapping at keel n chines. So 4 layers on these areas.
Im looking for a strong n lightweight finish.
Q1. Any advantage to altering layup to 6 +4+2? Less sanding maybe?
Q2. Is it possible to Vacbag the WHOLE outside of hull in one go?
Q3. What size Vacpump?
Q4. Where do i source the gear to do so? SE QLD.
Q5. Is this even possible for a FIRST TIME vacbagger?
The whole point of using plywood and glass is completely different to building a surfboard.
All those options are expensive and you will only make small improvements. For a lot of money.
Buy a beer brewing kit instead. Then just build the boat.
You could look into S-glass, carbon etc. Again all expensive. You could use only 1 layer or 6 and 4 in areas where the strength isn't needed etc.
Good quality plywood is the key to strength and weight saving. Marine grade Gaboon,Okoume. Different places call it different names.
Paying to have a light weight high build primer sprayed on will save you time and weight. Seal the plywood with a compatible product before glassing to stop the plywood soaking up the epoxy and reduce the risk of dry spots in the glass.
Select to expand quotetarquin1 said..
You could look into S-glass, carbon etc. Again all expensive. You could use only 1 layer or 6 and 4 in areas where the strength isn't needed etc.
Good quality plywood is the key to strength and weight saving. Marine grade Gaboon,Okoume. Different places call it different names.
Paying to have a light weight high build primer sprayed on will save you time and weight. Seal the plywood with a compatible product before glassing to stop the plywood soaking up the epoxy and reduce the risk of dry spots in the glass.
I thought the idea was for the ply to soak up some epoxy? WEST method wood epoxy saturation technique? Or is that old school and out of fashion?
Not old fashioned at all.
If you want to save weight which is what olskool was asking use one or 2 coats of a compatible wood sealer. This soaks into the ply more than epoxy and you create a chemical bond with the epoxy.
I use a polyurethane sealer thinned out 1:1. It's like water and soaks in. Then laminate in the correct time. No sanding.
I have asked 2 big companies SP Systems and Sicomin. Both companies said this.
Select to expand quoteImax1 said..
Question for the tech heads ,
For a wetted out on table then squeegeed onto the board ( without vaccing )......
Q 1 : is two layers of 4oz wetted together stronger than one layer 8oz ?
Q 2 : how much stronger and heavier would two layers of 4 oz , done one after the other after curing be compared to one layer 8 oz ?
Strength is one thing , stiffness and ability to resist weight compression and dings is another .
All thoughts appreciated
Mark is correct - if your are using standard plain weave cloth. Standard plain weave 8oz cloth will hold more resin & require more filler than 2 - 4oz layers due to the rough texture of the larger yarn bundles. However, you may find a tightly woven 8 harness satin weave cloth which not only has a very smooth texture, but also very dense with fiber so less resin filled void. There are also some non woven biaxial stitch bonded uni which could be pretty smooth & dense but they are harder to work with.
Regarding your methods IMHO either wet layup on the board, or pre-wet on the table & vac bag it.... Too hard to guaranty wet-out otherwise. One way that might work is to set part of your batch aside & thicken with micro ballons, then pre-seal the blank with that. Drape your wet fabric & squeegee it down. Or drape the dry cloth & wet out as normal. This gives a good lamination & keeps the blank from soaking up too much straight resin.
