Using double bias fibreglass.

I am about to complete two small foam sandwich hull constructions. The hulls are fully decked and the inside surfaces already laminated with woven carbon, but it has now become very hard to get and extremely expensive. I was intending to use 200 g.s.m. carbon, same as the inside surface, but can buy double bias fibreglass (+45, -45 ) very cheaply being 400 g.s.m. weight.
I am thinking that apart from a bit of a weight penalty this reinforcement might work really well, and certainly have more impact and abrasion resistance than the carbon, and probably as much ultimate strength.
I also think that the carbon on the inside rather than outside is the best use of the high tensile property of carbon if I was only prepared to put it on one surface.
Does anyone have much experience of using double bias fibreglass and like it more than standard woven fibreglass? If so, why?

 

Biax and Triax is stronger than woven cloth, most common use that I know of is in snowboards where weight to strength ratio is critical.

 

with woven cloth the overlap of the weave is a weak spot thats why bi and trial are the better choice if you are looking for strenth , the carbon 2x2 twill is a weaved cloth but only every second strand is weave so it is stronger than woven carbon cloth it is also very nice looking and in high demand and has gone up in price thanks to george bush who has ordered 5 battle ships in carbon fiber so the world market is selling to the us navy. also if you are going to infuse the glass bi and trial are muck better than cloth for resin flow

 

Frosh, I've used quite a bit of DB over the years, it generally conforms to surfaces quite well- much easier than tri or quadrax fabrics.We usually tailor it over lenghth & tape the cuts pre cutting- easy to deform fabric ends at 90 degrees from stitch lines(if that makes sense) then pre wet on say a poly film covered bench then roll on to a length of 90mm pvc stormpipe to transfer to job, some times we'll lay it dry & just wet in position-just depends on the job.It really dosen't like over handleing- roll precut lengths to stormpipe mandrels to keep it sweet & unkinked(same for any fabric esp' stitched).Use some peel ply with it & remove selvedge edge from peelply for less puckering along sides to get a flatter finish.Regards from Jeff.

 

Shame on Bush for putting the security of No. America before your amateur boat building needs. Sheesh!

 

my sulplier told me there is a 2 year shortage the manufatuers cant make it fast enough and there is a world wide shortage you can still buy it for 3 times what it was

 

Double Bias Carbon

I have just recieved all the carbon for our next race yacht.
The double bias carbon is an exellent cloth and in our case, we drape the hull at 45 degrees to give us a 0-90 degree cloth orientation for the best results for ABS building codes.
Yes, it is stronger than the woven cloths as the fibres are straight and not crimped into a weave.
It never looks as nice as the woven cloth for a clear finish, but the properties are much better. Take care to wet out correctly as it is a little tricky on the lap edges (twice the weight).
We are using infusion which hasnt given us any problems. We purchased woven cloth for the finer finishing layers.

 

Hi Jonsailor, I havn't come across diable bias carbon before but it sounds like it was due to happen. Is the core of the new yacht a type of PVC foam?
If so are you using carbon inside and outside the core?
Also are you orientating the carbon fibres at 0, 90 degrees on one side and
+45, -45 degrees on the other?
Can you tell me the suppliers name for the carbon?
regards, Sam

 

Double bias

Hello Sam, I will have to check on the box for the brand???
Our supplier is Fiberglass International and they will be more than willing to help out.
ABS does not take into account, the torsional loading of a yacht hull and thier primary panel construction is 0-90 degrees. However, as you stated, it is a good idea to have some 45-45 orientation.
Depending on the size of the yacht and the skin weights available "off the shelf" in carbon stocks, will help you decide in the final lay-up. There are minimal skin weights in ABS construction for your length of yacht (LWL+LOA)/2
We just launched our latest 12m yacht 4 hours ago and she is a beauty.
cheers
Jon

 

Hello Im new to this site I hope this can help you I work for Malibu ski boats we use double bias in the hulls and decks for strength and they come with life time warrenty so I belive that it would be a good chioce.there is triple bias too