Upgrade from 'E' Fiberglass to S-Glass Plus Carbon, material estimate?

I have the total materials list (but not the specific lay-up schedule) for a boat design I like listed in weights of cloth in Gsm, the width of roll, and total weight in KG for each type of cloth. It is mostly E-Glass as well as come uni-directional carbon and tapes for reinforcement.

I want to estimate the cost of materials if I upgraded the lay-up to S Glass and Carbon, leaning on mostly carbon. For the sake of simplicity I should probably just estimate it as all Carbon to give me the 'high-end' lay-up and maybe back it off later to an S-Glass/Carbon hybrid for a middle ground between an E Glass vs Carbon build.

Anyway, I just have the raw materials and not the specific lay-up schedule. I could just get my bulk prices based on the same weights and volume of Carbon as the E Glass but I think that defeats the point. If the layup requires a 600 gsm E glass layer, then in Carbon that same layer of cloth required would be about, say, 400 gsm? So generally, is there a rule of thumb for this reduction when using the stronger cloth? My general understanding is that carbon is 30% stronger than an equal weight in E Glass.

Before anyone states the obvious... yes, I could just ask the designer to give me a lay-up schedule and materials list in Carbon & S Glass but that would defeat the purpose. I want to do the math myself just to refine the skill, give myself an idea of the cost increase, and practice sourcing the materials myself. I am a professional logistician and procurement officer... I like to check prices and see if I can get a better deal, LOL.

If I were to execute the upgraded Carbon lay-up on the design I would certainly coordinate with the designer to get his approval of the lay-up. If I can figure out this part without much fuss then I will ask more questions about serial infusion...

 

This might help you to understand why you should contact the designer or an engineer to optimize the laminate

 

The first cost to consider is the re-engineering of the laminate and reinforcements. The math for inisotropic materials is a 21x21 matrix to solve. If you consider it orhtotropic as a simplification, you can get it down to a 6x6 matrix. I am not trying to insult you, but what is your level in Math?

 

@CloudDiver, I think it's very commendable that you want to make the calculations for the laminates yourself, but do you know the mechanical properties of the various materials you are going to use?, what formulas are you going to use?, what design pressures?, are you going to use any specific regulation?. And other questions besides the previous ones, do you really need to use S-Glass and Carbon?, what do you need to improve with them?
@Gonzo, what matrix do you mean? I have never used matrix calculation to calculate the composition of a laminate.

 

Gonzo... Thanks for your comment. I'm a Logistics and Procurement guy, so my Math skills are statistics and financial which are essentially easy compared to engineering math. I'm really not trying to re-engineer the boat. It was already designed to be built in Carbon and I'm sure the designer will already have a lay-up schedule for that if I just ask for it. The purpose of my question is to just practice 'roughly' what the upgrade cost from the bulk qty of E Glass to carbon would be based on my product sources in the U.S. Its mostly out of curiosity and I also want to compare my cost for laminate materials is the U.S. (with volume discounts I can negotiate) vs. the sourcing that has been quoted for the bulk material outside the U.S. excluding VAT. It's possible that I can't do any better on the price, but maybe I can. Anyway, not trying tor engineer the lay up, just see what the rough price will for the upgrade. The boat is a 44 ft catamaran and pretty light to begin with, not trying to turn it into a Gunboat.

 

Thanks TANSL... not really attempting to re-engineer the laminate, I would actually ask the designer for that to make it official. I'm just trying to get a ball-park figure of what the upgraded composite would cost in raw materials. I am a professional procurement officer so trying to beat quoted prices and find competitive sourcing is just what I am always tempted to explore.
The purpose of the S Glass is mostly just to replace the weaker E Glass here Carbon just isn't needed or cost prohibitive; taking advantage of S Glass' higher modulus without the increase in price to carbon by the square meter. Also, where carbon comes into contact with certain sensitive boat bits, the outer most layer of the laminate being S Glass/epoxy will isolate the carbon from things like stainless hardware.

 

I agree, your math level is more than adequate. Is this a cored laminate? That is where you could have a considerable savings in weight. Solid laminates are often overbuilt to be able to make them stiff enough. If you neglect puncture resistance for a preliminary calculation, using tensile and compression strength comparisons may be enough.

 

That, which I do not know how it could be carried out, would probably lead to serious mistakes.
There are also forces, called shear forces, that are very important and that must be studied.

 

Thanks Gonzo... The Cat is 12.8 m LOA, just shy of 7 m beam and displaces 4500 Kg. It can be built in foam core or balsa core. This is a 'newish' design, several examples of the 12 meter version in balsa core have been built and there are at least 3 hulls of the new 12.8 meter version in process, one with foam core currently in construction in the U.S. No one has used Vac bagging on a wet lay-up or infusion yet. This Cat is designed to significantly lower labor hours and overall build cost so I think these advanced techniques really aren't necessary, especially when the hull is coming in at under 5000 Kg in mostly E Glass wet-layup. That is pretty dang light compared to production Cats out of the factory molds in polyester resin. At this point I would prefer to do my core in foam vs balsa, I know balsa coring has higher compression and sheer properties than foam, but the trade-off is less than significant compared to the negative stigma (which is really only a poor perception) of balsa coring below the water line, just in the US really. Trying to retain a high degree of confidence in material engineering and build method to carry the hulls re-sale value in the future, so the U.S. buying public expects foam cores on composite boats and also them employment of resin methods like vac-bagging or infusion.
This is going to be my boat.... not planning on building for others (someone in the U.S. is already doing that). My goal is upgrading the laminate to S Glass and an increased % of area in Carbon is 'stepping up the game' for a version of the boat that is more unique among the others of its kind. Honestly, the displacement, strength, and performance of this Cat is excellent even in E Glass. I'm not trying to build a 'faster' Cat by going Carbon, however I probably will gain a few more kg's of payload capability which would be nice. I have not sailed any Cat bigger than a Hobie 17, but I understand how the bigger rising Cats are very weight sensitive compared to mono-hulls (by far). I'm not a big guy, don't plan to cruise with more than a crew of 3 and very few guests if any at all. I'm fairly certain I can stay within the design's 1500 kg payload specification, but it'd be nice if I could get a little more out if with a lighter, yet stronger laminate.
Everyone please understand... I am not trying to reinvent the wheel, much less someone else's design. I've learned that much from this forum that you can't just fat finger some numbers and material choices and improve someone else's work. I am doing this mostly for fun, my own learning, and exploring materials concepts. There is a good chance I will just build this Cat as designed, but there is an equally good chance that the designer will be not only be really excited to see a hull of his built mostly in Carbon/S Glass, but he will quickly email me a new materials list and lay-up schedule for those composites.
FYI, I am almost 40 this year and I am on track to retire (mostly) by age 45. My home pays for itself and if I rent it out fully it will give me $600 per month in positive cash flow, then be worth $600K in todays dollars when I do sell it down the road (that will buy my retirement condo ashore AND a second boat in 20 years) I already have a partial pension from my military service, and I will be vested into my 2nd pension in 14 months. With all of my retirement sources combined I will be worth $8 to $10K per month by age 62 which is more than what I make working right now. Between age 45 and 62 I will have enough monthly passive income to cruise comfortably and continue investing a portion of my earnings just as if I was still working. I appreciate all those younger couples out there who are just 'doing it', quitting jobs and going cruising.... I am the type that plans, saves, and mitigates risk (LOL). Besides, I don't think I would be any good a blogging or vlogging to generate income, plus I don't think I'm attractive enough... but my girlfriend might be!

 

You have a well thought out, organized plan. I also play around with numbers and designs that generally don't go beyond that. It is a good exercise and usually teaches you a lot about different options. I think that if you are looking at resale value, a laminate that appears more sophisticated and high-tec will be beneficial.

 

I'm still working on my rough estimates, and they are pretty rough at this point... With a little refinement I'll get to a general 'max' based on the same Kg of fabric in S-Glass plus some Carbon vs. E Glass. I'd like to be able to say, with some confidence, that I can go 30% less by volume in the stronger fabric vs. E Glass. At the end of the day I think the designer will gladly provide a lay-up schedule in the higher modulus fabrics. So far I've made some pretty good headway in sourcing Airex C70-75 & Aircell brand foams at competitive prices as well as S-Glass at pretty unbelievable price per yard in 50 inch rolls. Just those two alone are $25K in material cost before negotiating any bulk buy discounts. I sure hope my experience in price negotiations works with these suppliers... I have spent millions in tax payer dollars supplying the U.S. Navy under renegotiated contracts, its a whole different game when its your own pocket change, lol!

 

Have you thought if the changes you propose involve more or less labor ?.
In general, I do not say that this is the case, I would not like to design a boat based on the cheapest equipment that the purchasing department can get. I believe that the designer should design the boat with the most suitable materials and equipment to meet the ship's SOR (with criteria of weight and labor savings) and that the purchasing department get the best prices for those items. But this is a debate that, I think, has no solution.

 

Hey TANSL I didn't see this post until just today... my 'alerts' don't seem to be working. The overall design of this Cat and its kit form in flat panels is very much centered around reducing labor hours. What I didn't understand before that I now have a better perception of (by watching the ongoing build progress of other hulls of the same design) is that the majority of the lay-up is done on the flat panel prior to CNC cutting. The hull parts are assembled and the seams are taped. There is some uni-directional carbon in high stress areas that is a wet lay-up, but beyond that there is little glassing of fabric in full width. What I don't like about this is all of the interrupted fibers at the taped joints. I would prefer, if possible, that only the minimal amount of lay-up is present on each panel when it is cut. I would then want to a lay-up of as much fabric as possible that is full roll width via serial infusion. In that case it definitely has the potential to increase labor rather than decrease it.
Overall, if I were to use high strength fabrics, the lay-up should be less as I also shed weight and have less resin content. I still haven't finished my analysis of the kit cost as it stands with a mostly E-Glass lay-up. My current hunch is that it isn't the best deal but I could be wrong. The amount of time saved by having the pre-cut panels in full 12M length (thus saving numerous scarfs and taped seams) vs sourcing my own core material, composite fabrics, and doing all the panel infusion prior to CNC cutting probably trumps any savings I might garner in sourcing my own materials. I'm still interested in an S Glass and/or carbon lay-up, but it could just be a pipe dream.

 

Ok I understand how its in ones nature to try and improve on others work.
Building a catamaran lighter is always an improvement if there are no negatives.
I'm guessing we are talking the Schionning Arrow series here?
Getting rid of the Balsa , contrary to schionnings bull reasons are a great start.

As far as calculations regarding a blanket formulae for changing to a lighter stronger glass you need to consider
what the glass is doing in a particular area of the boat.
If the design calls for impact protection on decks and keels then lighter is not neccesarily better.

The best place for a lighter carbon laminate would be on the inside. Specifically the inside skin where it has protection from point loadings and beam caps. The similar foam glass 40 footers I 've been involved in building have had poly resin and 400db as an inside skin.
Remember ATL like a minimum of 600 gms on each side of their product cause its a suitable thickness to machine a scarf join in and being 6oogms both sides there is no tendancy to warp the panel as the resin shrinks as it cures after manufacture. It has nothing to do with the optimal engineering for the catamaran design.
If cost is of no regard you could save 10 kgs total (guess on surface area) and probably go for 300db carbon and epoxy instead.
Before all the textbook terrors get on their high horses this is speaking from a practical experience view point.

Being built in flat panels the biggest weight saving would be to ditch this method and the miles and miles of DB Tape and build the boat as one piece(as practical as possible) on a batten mould A LA Farrier, using UNI (so theres no overlaps,and little waste) with Vacuum bagging , but definitely not infusion if you are cutting resin channels in the foam or using contour foam.

Remeber the hull exterior is only a small portion of the complete boat.

Remember that these boats are light cause they have nothing in them and no pay load to speak of.

May I just add that laminate schedules that are professionally produced are a hell of a lot heavier in general,than what has been produced by the seat of the pants time tested suck it and see techniques.

Ask Derek Kelsall what laminates have stood the test of time on Toria stuck down with very shi##y early poly.



I have been genuinely shocked by some of these profesionally produced schedules and can only put it down to an arse covering exercise by the engineer/NA.

 

Bruce, thanks for your thoughts. Yes, the Arrow 1280 is what I am interested in. I understand your points about the laminate and impact resistance, etc. I am mostly curious about the feasibility and cost of upgrading an E-glass schedule to S Glass and/or Carbon in terms of benefit (strength, stiffness, weight reduction) vs. the Con of extra cost. I'm not so much trying to improve on the designer's work as I am trying to squeak out more payload vs total displacement. The arrow 1280 is advertised as displacing 4500 kilos with an available 1500 kilos of payload. I also assume (hopefully not foolishly) that Jeff Schionning would like to see the performance cruising Cat built in Carbon if a client was willing to foot the bill. I'm really just curious if the endeavor would be worth it, because as you pointed out I may save only 10 kilos over a given surface area but have unfavorable impact resistance at a much higher cost. Its reasonable to say that 4500 kilos is pretty damn light for a 12.8 meter catamaran and I should just build it as designed.

I agree with you on the balsa vs foam. Balsa is heavier per cubic meter and more expensive (more expensive from ATL down-under, balsa core is actually cheaper than foam in the U.S.). It may have a higher sheer strength and impact resistance than core foams, but the biggest hurdle for the U.S. market is the negative perception of balsa and water intrusion. It's an unfair perspective to the material that is a result of poor boat-building and not a failure of the material, but that's how things go. I don't want to build it to sell, but I will sell it someday down the road and I know a foam core will be what U.S. cat buyers want.

I'm still more interested in the flat panel construction method than building station molds. I understand all the double bias tapes will add bulk/weight where it wouldn't be needed in a station mold build.... but the savings and time and labor on the flat panel construction outweigh (pun intended) any negatives.

The good news for me is that I'm not starting this tomorrow or even next year, but hopefully within 3 or 4 years. There are several Arrow's under construction right now with a good deal of documentation going on. There is a 1340 in the Netherlands and a 1280 being built in Virgina. There are few more Arrow 1200's and 1280's being built in professional yards in Australia and South Africa. I will see how things turn out with those and hopefully get see/sail one before I start mine.

BTW, I won't be using ATL panels. I'd like to infuse my own panels if I can, but worst case if I order the pre-fab kit it will come from South Africa with PVC80 core. It is within my capability of building a CNC router with a massive 40 foot X axis, but again; cost vs. benefit. What will I do with such a machine after I've cut my panels? LOL