Layup schedule help

I think it is best that you consult your supplier about the exact weight of the fabric and mat that the sample you are considering has. Regarding the weight, you need distinguish if it is dry weight or weight once impregnated with resin. The latter is the one that will give you the total weight that is probably the one that interests you.
A triaxial weave will be, surely, much more resistant than what you have now but that does not guarantee that it is worth using it. If you really want to get into complications, you should first define if you want to get the minimum weight, the least number of layers or the minimum thickness laminate. Clarified that perhaps you should ask someone to calculate the optimal scantlings for your boat, according to that criterion and imo it would be best to talk to the boat designer.
The gelcoat is used to improve the esthetics of the outer surface and give a bright appearance to it. It also provides resistance against UV rays and hydrolysis. I do not think it protects much against abrasion, among other things due to its very small thickness, 0.6 or 0.7 mm. In another thread of this forum I have seen that some South African catamaran manufacturers use an outer layer of basalt fiber to improve abrasion
Excuse me for not being able to, not knowing, giving better explanations.

 

Correct but the mat is only 50 gr/m2. The DBM 1715 is TOTAL 1,060 gr/m2 (31.2 oz/yd2) with a 50 gr/m2 (1.5 oz/yd2) mat. That leaves us with a uni arranged in +45-45 of 1,010 gr/m2. It is the code used by the weavers Advanced Textiles or Knytex.

 

Can you post a midship drawing and a profile drawing? The numbers do not add up. A simple displacement check for a cat disp is Lh x bwl x draft x Cb x 2 hulls seems off. Cb for typical ellipsoid hull would be 0.42-0.45. I could not even get past the panel loading calc if the particulars are not correct. I need also the spacing between bulkheads or frames to get length of panel to be analyzed. We are going around in circles trying to guess the parameters.

 

Is it ok to post pictures of the plans?

 

You can make a crude drawing if the designer will not allow you. Otherwise PM me the plans if the attachments will work. JPEG i think.
See what I am getting and the proportions:

 

Rx-Isn't the mat weight per sqft?

I thought it was
17 oz
Plus 1.5 oz times 9 sqft/yd or 13.5 oz of mat per yd? For 30.5 oz net.

If the mat is removed from the fabric; aren't you left with 17 oz no mat equivalent?

So, could not the builder upgrade his fabrics/strength for no weight penalty?

And would it be unusual or typical to lay the fabric on 45s to the CL/WL as the OP asked for round hull? This seems to be your area of wisdom.

And, of course, highly relevant with any fabric changes.

with much respect...Dan

 

Data from Manufacturer

Note: 50 gr/m2 (1.5 oz/yd2) is insignificant. At this weight, it is just a veil cloth or surfacing mat.

Edit: Posted the one without formula.

 

No. Sorry, this is incorrect. The DBM x has 350grams of mat in it. There is no uni, unless you are referring to the db as uni? It is 610-710? grams of db fabric with a veil on one side and thicker mat on the other. Knytex is a funky fabric with mat on each side of the db. It is not a good example unless you are recommending it. A clerical matter.

My point, though, is very, very simple. The OP could use a different, beefier schedule because his weight is 31.2 ounces. I am not smart enough to say what it could be; just that the opportunity exists. An example would be two layers of 12oz db no mat, or even a 17.7oz db no mat with a 12 oz db no mat, or a 22 oz triax (although the fiber orientation is a question), etc.

And he still needs to understand how the db is to be laid on the hull. Again, way outta my league.

with much respect

 

You are giving me a hard time Dan. This is the data from the old Publication of Marine Composites. It says "knit" but not "woven". I will assume it is a uni in a +45-45 layup in the meantime until I look up the laminate material properties. It appears in the new version and shows different fabrics laminated with Poly, VE, or EP.

The page I scanned is from Knytex. Advanced Textiles (AT) uses the same code and is similar.

As I have said, It is impossible to calculate and find out which material can be substituted as long as the data is incorrect. It is a long and tedious process and I am willing to go the extra mile. But first, I have to know the particulars I asked to calculate bottom pressure and I have to know how long the supported panels are to make up the tabulations. Only then will I be able to analyze the layers involved. Just wait because I will explain the rationale behind it.

 

RX - I honestly am only trying to learn here. Please understand. If the knytex was the specified starting point, then so be it. If so, then I would just assume, rightly or wrongly, that the 300g mat offered some strength. Even when someone is trying to learn, if you see 2x3=7; you would probably say so.

This story is similar to my experience, however, my designer was involved and helpful. He and I went back and forth a bit before finally deciding on the laminate. He understood I wanted to use epoxy and he understood I had no wish to use gelcoat. So we moved away from 600g mat stuff. Scuff is lucky to have someone help him a bit.

I will just watch and learn; sorry to be a bother.

 

Fallguy- I am sorry for the strong words. Somebody asked for the manufacturers material property and nobody did so I dug up my old books and searched the internet myself. Since the 1715 was the designers choice, we have to use that as a baseline. I have not used 1715 myself so I can only rely on published data. Knytex is only a manufacturer, So is AT and Owens Corning. 1715 is a product code. If there are other data otherwise, show me, but for now 3 manufacturers all showing the same configuration will suffice for me. It is not the procedure to have personal knowledge/product use/I think to design. I only look for reliable data published then choose.

Personally, I don't poke my nose into somebody's design then change it. That would be unethical. But since we are looking for substitute due to a change in process/materials, we have to look at all angles (strength, modulus, thickness, ect.)

That is why I have to pinpoint exactly the original designers thought, then come up with a substitute.

 

https://www.tapplastics.com/uploads/pdf/Knytex X-Mat Data.pdf.

 

Owens Corning purchased Knytex - this may or may not change your approach, but it looks like the best data available. OC no longer says it has the 50g mat, but if you read the starting page; it says veil can be added. OC won't even talk to a small buyer, so modifying the fabric would only be something a big boat manufacturer would get away with.. I called OC once upon a time and never got a return phone call on a mundane and decent question about their products. Where to buy one of their fabrics at retail.....

 

I used OC to validate the specs of 1715. Their laminate data sucks anyway. Not enough info but found the complete laminate data in my reference book. Found also Gurit PVC foam core specs.

If you read carefully the opening lines, they are descriving Double Bias Fabric or DB. DBM is Double Bias with Mat. Nowadays it is coded a XM. +-45 for the X orientation and M for mat. If it is a triaxial, it is Y.

 

As far as I have read before, OC manufactures glass and is one of the biggest glass suppliers. They sell raw materials in bulk. Then came the independent "weavers". Companies that designed the type of weaves that has become an industry standard. Being independent, they are free to weave fabrics like Kevlar from Dupont and Carbon Fiber from Toray and other specialty fibers.