Tell me what you know about core matt !!

I have been and used acres of core matt over the years while i have been in the marine andCommercial and Industrial Glassing Industries . Every laminater i have worked with has never been able to tell me what core matt is meant to be used for .
Sure its a core and it soaks up lots a resin !!
Thats the same thoughts every one has world wide it appears .Have you ever checked to find out the recomended amount of resin to use per square meter for a given thickness ?? There is a chart thats obtainable from the supplyers but they dont like to hand them out or you will find out what i found so long agao and possibly come to the same conclussion i did 30 years ago !!
Like all materials used in the marine industry they have been adapted and come from other parts of the Composite industries mainly industrial and commercial . What they get used for in Boating is not what it was origanally designed for in its originaly form way back in the early 1980s.
The company i went to work for were using it in Camper tops and had had a few inital issues with it in the begining . The first panel i used it on went to the waste because i though of it like every one else even to this day still thinks .
One thing to remember when using core matt is YOU CAN NEVER OVER WET IT !!! Call me a idiot ! lots have before you so join the long line that have gone before you !, as stated in the Video on Spherecore its impossible to over wet the core matt and if you done wet it enough you will end up in trouble !! When you think its over wet you simply need to put a layer of glass over the top and laminate it with a mohair roller !!!.
Ok thats me i want to hear from everyone else thats used and is still using Core matt , any type in any industry . need you feed back please!!!! .

 

well actually I have the chart from Lantor .. if you want it i can send it to you
now I haven't used much of this material, but I'm planning on using it on a deck project, so any advise would be interesting ....

 

Hello What is the chart you have ? Yes i would like a copy if possible please !
The deck you are building , how big is the boat ??
I changed a whole boat some time back and built the deck complete from Glass sheets core matt stiffened !!.
Laid csm 450 gram then 4 mm coremat 450 gram csm glass , made thin ply patterns of the shapes i needed and then made and cut the glass to the shape and fitted it , use temporary thin ply knees to hold everything in place with a hot glue gun and then glassed the top first so it was strong then removed the ply holding it in place and glassed the underside , used Peel ply to help make the surfaces fair and smooth . ALSO the sky bridge panels on the 147 foot super yacht on my avatar were done the same way and made the panels on a big work bench . Then they were taken to the boat for final shaping and fitting and the last layers of glassing done on site .
Its good to work with and you can be quite creative with it . Only major draw back i have come across is Never use it in the bottom of a hull as it will not stand the continual flexing that hull bottom panels get and falls apart after a period of time !!! very scary !!!specially doing 20 knots 10 miles off land !!!!.

 

Best advice with any of these laminate bulking mats is to at least prewet whats to be the underside so it dosn't scavenge resin from the chop its laid onto, also 'cos its so resin hungry adjust catalyst levels down within limits as it gets a bit warm esp in 4-5mm range. All the producers sites seem to list resin take up rates for these products, usually about 500-600 GM2 per mm of thickness, I seem to remember using about 3.6kg per M2 when sandwiched between 300GsM2 choppy with 4mm Upica on a job. Its terrific material, & can be used sub wl if the laminate & framing sched are correct- used in large panels in the bottom of a planing hull as stated may not be ideal. http://www.frpservices.com/html/che_html/datasheets/U-PicaMat.pdf http://www.lantor.nl/index.php/id_structuur/10598/coremat.html http://www.spheretex.com/en/voluminisierteprodukte.html All the best from Jeff.

 

how can i send you the .pdf file ?

about my deck project, it's a 42feet 1979 taiwanese production ketch
the deck core is completely rotten due to billion screws driven into the core to hold the teak .
now the idea is to open the outer skin, scoop out all the rotten ,redo the core, and relaminate the outerskin.
the original core was made of little pieces of plywood with large amounts of putty over, below and in between, and once i have all this stuff out and the new core down (here i only have available 5/8 balsa core) there is still more than 6mm to get at the original deck level.
To cut on weight and cost I'm planning on using coremat for thickness and double bias for strenght 450 csm-coremat-dbm-450csm for the outer skin
what do you think?

 

Dont you just love the blocks of plywood thing !! I did my nuts a few weeks back when i caught some guys going to do a big hatch the same way !!!Picked up the hatch and emptied it in the bin , was one pissed off fella watching me . Just shook my head and waved my finger no no no !!!!.

After you clean out the old stuff what do you intend to do from there !! fill us in on your plan of attack !!!Give us a bow by blow report !!
Please !!!

Sending a pdf ! File at top left of tool bar , look down and see attach to Email !!

 

here comes the lantor technical sheet.pdf ..
about my project, well a lot of grinding and sanding to get all the bumps
left by the putty ..
same filling and fairing to have a fairly even surface to bed the new core
and then new lamination ...
what do you think of 450csm+coremat+dbm1708+450csm?
original was 2 layers of 24oz roving sandwiched between csm...

 

I don't understand, what is the coremat supposed to be doing for you?

I'd think, csm, 1708 (x2) then a csm That would be closer to the original wouldn't it?

-jim lee

 

the problem is that i only have available 5/8 core and the original was 3/4,
so there's 1/8 i have to fill ... and that's why i am planning on using coremat

 

Tunnels, do you realise that there is a whole (polyester) industry besides boats that use Core-mat for a long time, and without any problem?

Also, datasheets nowadays are downloadable from the manufacturers websites, in general. Lantor is no exception on that. These datasheets tell you interesting and useful information.

 

I spent a lot of time glassing industrial and commercial products and some of the panels used core matt but there thinking was completely differant from the guys building boats . Personally i quite like it and have use it in layers as well but always put a layer of 450 csm between the layers of core matt . Once i realised its impossible to over wet my whole thinking changed . Just have to be careful with panels of products that flex and vibrate in any way . Have seen a few things come apart ( Shear ) over time .
The worst was a whole bottom outer skin came off a power boat and snapped off at the transom and sank , but the boat managed to make it back to shore on just the inner skin .

 

I do not feel it is in place in dynamic loading situations, except when other resins are used (more elongation). In the building industry it is a big market. All mostly decorative products, loads are mostly static and low, and manhours are more important than weight of the product, or resin consumption.

Still some types can be used in boating. The thin Soric TF material is quite good in suppressing print due to heat build-up. Also, some recreational boats in NL use it as a core, but these boats never get loaded. Most have perhaps 9 or 12 HP, and maximum speed is 9 km/h. That is inland boating in NL.

 

I think SORIC, the infusion version of Coremat is heavily used for Minitransat hulls. Mini transat rules for series units forbid sandwich with foam core. But soric is considerd as a monolithic hull. (Even in ISO 12215). And they need some thickness without weight. So they nearly all builders use Soric or similar as thin core.

 

In that specific case I guess Soric is one of the small number of options, besides thick (and heavy) laminate, or thin laminate and a whole load of framing.

There are more examples where solutions that do not sound practical or reasonable even, will still be the optimum.