CSM/WR vs Stitched Bx/Qx

[MattStudent]

Hi everyone, my name is Matt im new to the site.i am 21 and a student at Sothampton Solent University studying yacht manufacturing and surveying. i am currently writing my dissatation; an evaluation on csm/wr. aiming to answer the question why is csm and wr hand laid still being used widely throughout the industry when new materials, namely stitched fabrics such as Bx and Qx etc are available. focusing on polyester and glass, from my research into production boat builders it seems that around 75-80% of the industry are still using csm and wr. would you all agree with this figure? can any of you suggest some reasons for this just to check ive covered everything! any response appreciated, cheers, matt

[jimslade]

It's hard to change a tried and proven method even if there is a better way and training takes time and time is money. ( nice run on sentence).

[Herman]

CSM is about 2 euro / kg (or even less)
WR is about 2 euro / kg (or even less)
Gun roving is about 1.5 euro / kg (or even less)

Multiaxials are more than 2 euro / kg

It's that simple...

However, there is a trend towards other materials. Surface quality is important, and is more difficult in infusion (large stack of material, lot's of resin, high peak temperature...)

Some reasons to change to multiaxials:

-better surface quality
-heavier fabrics, less layers, saving on labour
-stronger and more stiff, if compared with a CSM laminate of the same thickness
-less resin usage

In the DIY boatbuilder industry, we sold a lot of UD tapes (glass). This has changed almost completely to multiaxials, due to better handling and easier wetout. Also, with a +/-45 degree multi, there is no need to layup the layers angled to the centreline. We sometimes cut the rolls in half, so one man can manage them.