carbonfiber/kevlar layup

[power of one]

Mr Concrete i,m with gorilla and tunnels coremat sucks it is a poor mans stiffner between chop strand just remember you can use stitch cloths like quad and vinylester with Klegecell stringers will still make for a light strong rig and won,t hurt the pocket space them 300 -400 mm apart a couple of gussets 10 mm kleg floor quad both sides your away however your kevlar carbon is a good idea though how much glass is in the shell allready is it worth the hitech materials .

[Gorilla0178]

I'm not a huge fan of the coremat, it yealds no strength it just absorbs resin.

Need to put the record straight here!! do you understand what corematt is used for normally ??
Anyone know !!
Im going to wait for a reply or two and see if anyone is on the right track and understands the properties of core matt and its uses !!

No answers yet. We just used it in cheap layup for consoles between mat and stitchcloth. I've seen material like it used as flow media for infusion but not sure if its the same. I thought it was just a bulk builder or a print blocker to block print through.
Any answers close????

[mercurypro]

( quote it is a stiffner used between layers ) this is from my rep who has sold the products for 0ver 25 years for the number 2 largest dist of resins etc.. and too the largest yacth mfg in the north..and your answer is .. and yes i use it .. but i dont like it

[tunnels]

Core matt you either like it or you dont !! i hope everyone will have a rethink about what iv'e written on this subject !
The thing is it used for things and in places it was never intended to be used and theres that preconcieved idea it soaks up resin !! yes it does soak resin because thats what it is designed to do to give you thickness .

ok lets get to the basics and you can draw your own conclussions for it
Like the name says its a core yes and its made from A glass matt thats been bulked with displacement Q cells .
Now has anyone actually disected it and had a really close look at what your buying .
It was advertised in the early days as a stiffener and bulking layer for not only flat areas but also products that have shape, curves, hollows, and humps and lumps . Places where its just about impossable to lay a foam or balsa core without having a lot of problems getting it in and stuck down .

Its also used a glass replacement to speed up the manufacture of a solid glass panel of a given thickness .
Example= if you need a 1/4 of solid glass then you would lay down 2 layers of csm + 3 mm core matt + 2 layers of csm ,when wet out you would have your solid glass panel but a little lighter because corematt dosent use as much resin as 3mm of solid glass , it also gives the benefits of rigidity being a core that conforms to almost anyshape when its wet .
Over the years a million uses have been found for it . But it has a problem of shearing under bending loads such as the bottom of a hull where it flex's hundreds of times a minute when powering across the surface . Hull sides ok also as a print through blocker under a foam or balsa core, but its the thinner corematts that are used there . and it should also have a layer of glass between the core and the core matt . The worst thing you can do when using core matt is not put enough resin on it . If you follow the instrucion sheet it will tell you x amount of resin to wet out x square feet of x thickness of core .
I find its best to wet it so it is runny wet then put a dry layer of glass over the top and roll it over with a mohair roller , the mohair picks up the surplus resin and wets out the dryer places but it should still be wet enought to gently roll with a steel laminating roller , Notice i said gently roll not lean on the roller trying to squeeze it so the resin comes out ,That action is defeating the purpose of using the corematt .
Looking at it realisticly it using less resin anyway for the given thickness of lay up its creating and giving you the added benefit of stiffening that area as its a flexable core matt material !!
Its not the corematt thats the problem it how we have been bought up to think about it , change you thinking and you will see its a fantastic material when understand how it works and use properly . Like all good things it has its draw backs !.
Its good to use and has excellent compression strength as a bedding layer under things getting bolted down its not as hard as solid glass but harder than most woods solid or ply !!
Never under wet it !! when it has all the resin it needs it should look and be completely soaking wet and best to put a layer of dry glass over and wet that was well !!!!!

[tunnels]

No answers yet. We just used it in cheap layup for consoles between mat and stitchcloth. I've seen material like it used as flow media for infusion but not sure if its the same. I thought it was just a bulk builder or a print blocker to block print through.
Any answers close????

You are partly right on both accounts !!get a sample next time to disect and slowly tear apart to understand what and how its there for
What you are refering to is very simular and is there to do a simular job as core matt !! its to give the lay up thickness . Think about this!!!
If you have 1/4 of a layer and squeeze it to half that thickness then you wont have the same rigidity as when it was 1/4 thick !!, Infusion squeezes and compresses the layers of glass and so a good amount of rigidity is lost Engineers had to come up with a bulking layer to get back to the simular thickness but not use the same amount of resin as the original layup .
Core matt does the same job in a standard hand lay up . !! Core matt uses less resin for a given thickness than solid glass lay up .
Undrestanding the materials we work with and use is not that hard .

[XstreamVking]

Allways thought coremat was just good for eliminating the possibility of woven or bias glass from printing thru. And for mold making coring. Never would use it for a light wt. race hull. Use the weight of the resin and coremat to make some short stringer sections..Would be stronger i believe...

[OFFSHORE GINGER]

Understanding materials is basically very easy like Tunnels stated but i have seen to much de lamination from it and with that in mind one prime example is on Wellcraft Scarab's , where time and time again , i have seen more then one bottom of the motor compartment area ( running surface ) totally delaminated because of core mat and these boats did not even do triple digits so if you all want to use it by all means do so and like TUNNELS said its all about understanding materials and to tell you the truth from my past experiences with core mat , i would not have the stuff shoved up my a$$ .

[racerx]

Allison boats use cormat,and i have had great luck with an allison...How would you repair a crack in a kevlar boat?Would fiberglass matt and resin be good?Thanks

[Gorilla0178]

Well its always nice to learn something new and more about something you've used before. I personaly have used and I'm not exaggerating hundreds of rolls over the years building center consoles. We built hundreds and hundreds of them each year. I cant even guess how many rolls of material i've cut. I was the only guy at the shop that did all the material cutting and we built them every day. I've disected coremat before and it looks just like tunnels said, a glass mat filled with what I didn't know was q-cells but that explains alot. We used everything from 1mil to 5mil, the 3-5mil needed to be pre wet on one side before it was put down cause the resin wouldnt soak through the thicker material. Thanks for the info.

[tunnels]

Never would use it for a light wt. race hull.

Need to re read what i wrote about its uses . This is completely the wrong thing to use if you are trying to save weight , thats not what its meant to be used for anyway !!.
In the begining it was used for the industrial glassing industry but like everything found its way into Boats .

[Gorilla0178]

Allison boats use cormat,and i have had great luck with an allison...How would you repair a crack in a kevlar boat?Would fiberglass matt and resin be good?Thanks

Like tunnels said, it can be used in topside parts but it shouldnt be used in the hull of a high perf. boat. If you take a piece of coremat and wet it out, when its cured it will break like a cracker. It has no strength by its self. Repair the crack like any other, I would add a little extra. If you had a little kevlar I would repair it with that.

[tunnels]

Understanding materials is basically very easy like Tunnels stated but i have seen to much de lamination from it and with that in mind one prime example is on Wellcraft Scarab's , where time and time again , i have seen more then one bottom of the motor compartment area ( running surface ) totally delaminated because of core mat and these boats did not even do triple digits so if you all want to use it by all means do so and like TUNNELS said its all about understanding materials and to tell you the truth from my past experiences with core mat , i would not have the stuff shoved up my a$$ .

Who ever spec the use of corematt in the bottom a boat like that has never done time on the floor of a glass shop of done repairs and certinly dosent understand glass materials .
The first time i ever saw it used in the bottom of a boat i shuddered . Sure enough the boat was back with the whole bottom blown off from chine to chine and there was just the inside skin keeping the water out .

Please take note of what i am going to say!!
THERE IS ONLY ONE CORE FOR THE BOTTOM OF A HULL AND THATS BALSA !!

Have a good new year !!!

[Gorilla0178]

THERE IS ONLY ONE CORE FOR THE BOTTOM OF A HULL AND THATS BALSA !!

Have a good new year !!! [/QUOTE]


Only balsa???? I dont want to start another one of these debates but thats harsh

Happy new year to you too!!!!!!!

[tunnels]

Well its always nice to learn something new and more about something you've used before. I personaly have used and I'm not exaggerating hundreds of rolls over the years building center consoles. We built hundreds and hundreds of them each year. I cant even guess how many rolls of material i've cut. I was the only guy at the shop that did all the material cutting and we built them every day. I've disected coremat before and it looks just like tunnels said, a glass mat filled with what I didn't know was q-cells but that explains alot. We used everything from 1mil to 5mil, the 3-5mil needed to be pre wet on one side before it was put down cause the resin wouldnt soak through the thicker material. Thanks for the info.

You are using for things it was meant to be used for stiffening and to do away with solid glass panels .
Consoles need to be stiff, robust and get things screwed and bolted to them so its perfect for that also seats and boxes and internal paneling such as coamings etc etc .
Yes its best to wet out the underside first and then turn it over and wet the top as well but again dont skimp on the resin , those little bleed holse should be filled with resin !! if they arent its not wet enough !!!
So when you wet it out if the resin is running out just put a layer of dry glass over the top and mohair roll it !! Try it !! it works a treat believe me .
Like you i to have used acres of the stuff . A saturator gun is the best to wet it with because its quick and you get a good amount of resin on the underside to bring it up to the surface specialy in the 2 or 3 mm thickness .I must admite the name is a bit misleading core matt.
In Korea we used loads as a way of building the thickness quickly on the moulds we were making for the 36 ft match racing yachts .There was non used anywhere in the actual boats just the moulds thats all !!.

[tunnels]

THERE IS ONLY ONE CORE FOR THE BOTTOM OF A HULL AND THATS BALSA !!

Have a good new year !!!

Only balsa???? I dont want to start another one of these debates but thats harsh

Happy new year to you too!!!!!!![/QUOTE]

On this site i feel we are here to try and keep it simple and to keep people out of trouble and make life easy for all to understand and do the work .
Only use balsa in the bottom of powerboats ! is that simple enough , what you use in the topsides is a whole differant story !
If you say use foam you need to specify the name and its density , its type and the manufactures name !!.
Balsa is balsa !!!
P V C Foam is a whole differant thing !,theres a list as long as you arm and not all are suitable for one particular job .
And if your thinking nomex honeycomb , paper or aluminium then you are in the wrong place .
Simple things work best !!!