Polycore

[groper]

Yep, i doubt theres a single person reading this that doesnt understand whats going on here...

For the record, i Build in an identical method to the one youve just shown in the PDF you attached.... For the same weight polycore panel with 0.5mm skins, 3.7kgs / m2, i have a 15mm core with 600gsm dbias structural laminate both sides, perfectly fair, and ready to paint (no pinholes). Adding this laminate results in 2.4kg extra weight per m^2 plus the cost of the resin and glass to lay it, and now i have glass overlaps to fair out...

Lets look at the trade off? Cost...

i make my own infused foam core sandwich panels for just on $100 per m^2. Thats 80kg foam, and 600gsm e-glass epoxy skins, peel ply both sides. In a small shed it takes me around 0.6 hours per m^2 in labour time - i could cut this in half with a bigger commercial shed.

Using pre-glassed polycore @ $77 per meter, i have to add 1.2kgs of e-glass, 1.2kgs of epoxy, and 2m of peelply to save sanding later. Thats $12 for the glass, $24 for the epoxy, and $4 for the peel ply. Total = $77 + $12 + $24 = $113 per m^2. Its too difficult to work out how much labour it would take to apply the laminate, and then do the fairing and preperation for paint, but there is no doubt in my mind that it would be an order of magnitude greater than 0.6hours per m^2 considering both sides need to be done allowing a cure for each side between.

So net result, costs me more in money $100 vs $114, costs me more in time, and my finished structure is 2.4kgs per meter^2 heavier based on a 600gsm structural laminate.

 

[brian eiland]

I'm having just a bit of a problem understanding your posting Should it read a little differently?

For the record, i Build in an identical method to the one youve just shown in the PDF you attached.... For the same weight polycore panel with 0.5mm skins, 3.7kgs / m2, i have a 15mm core with 600gsm dbias structural laminate both sides, perfectly fair, and ready to paint (no pinholes). Adding this laminate results in 2.4kg extra weight per m^2 plus the cost of the resin and glass to lay it, and now i have glass overlaps to fair out...

I make my own infused foam core sandwich panels for just on $100 per m^2. Thats 80kg foam, and 600gsm e-glass epoxy skins, peel ply both sides. In a small shed it takes me around 0.6 hours per m^2 in labour time - i could cut this in half with a bigger commercial shed.

Should that read like this?

For the record, i Build in an identical method to the one youve just shown in the PDF you attached....I make my own infused foam core sandwich panels for just on $100 per m^2. Thats 80kg foam, and 600gsm e-glass epoxy skins, peel ply both sides. In a small shed it takes me around 0.6 hours per m^2 in labour time - i could cut this in half with a bigger commercial shed

For the same weight polycore panel with 0.5mm skins, 3.7kgs / m2, i have a 15mm core with 600gsm dbias structural laminate both sides, perfectly fair, and ready to paint (no pinholes). Adding this laminate results in 2.4kg extra weight per m^2 plus the cost of the resin and glass to lay it, and now i have glass overlaps to fair out...

 

[brian eiland]

That was an interesting comparison Groper. I looked up a number of other subject threads that were started by yourself, and found lots of interesting discussions and photos of your experiments with building. I need to do some reviews of that info as well.

I would ask if you have experimented with Derek Kellsall' KSS building system? He ends up with 'finished panels' if I remember correctly. I'll have to look at that again as well.

 

[groper]

Basically yes Brian, i make my own panels using foam core rather than polycore. I cant use polycore because i make the panels via resin infusion, and the cells would thus fill with resin.

My 15mm thickness, 80kg/m3 foam core panels with 600gsm dbias eglass epoxy structural laminate weighs 3.7kg per m^2. The polycore panels with the minimum 0.5mm skin thickness, weighs the same. However there is no structural laminate on them. To add another 600gsm dbias laminate onto the polycore preglassed panels, adds 600grams of fibre to both sides, and 600grams of resin to both sides - an extra 2.4kg heavier per square meter of panel area or approx 60% increase.

The other point i was trying to make, is that after adding this laminate, ive also spent more money compared to if i just make my own panels from scratch.

The icing on the cake, is that after wetlaminating over the preglassed panels, you then have glass overlaps to fair out, which is a horrible thought considering one started with already fair panels!

I dont understand the mentality of offering such a product for sale, unless strictly used in non structural applications where no additional laminate needs to be applied....???

 

[tomas]

...

I dont understand the mentality of offering such a product for sale, unless strictly used in non structural applications where no additional laminate needs to be applied....???

This is how she answered this earlier:

...

As you may know....
About 80% of the marine boat building industry had dissapeared over the past 4 years
the world down turn...was a difficult time.....for the marine industry.

...


I must say ...It has been the home builders that has kept our panel going while the down turn was affecting all major boat manufacters here in Australia and the world ..... and I wish to say .... Thank You for you support.

...

Cheers Maggie

Hopefully, if there is sufficient demand, they could provide the options that you have described.

 

[groper]

That was an interesting comparison Groper. I looked up a number of other subject threads that were started by yourself, and found lots of interesting discussions and photos of your experiments with building. I need to do some reviews of that info as well.

I would ask if you have experimented with Derek Kellsall' KSS building system? He ends up with 'finished panels' if I remember correctly. I'll have to look at that again as well.

I basically emulate kelsalls KSS system. The key difference that sets his method apart from all the other flat panel building methods, is the way he lofts the hull profile, makes appropriate dart cuts, and folds the panel in order to get a slight compound curvature in the bilge area - which needs wet laminating over and fairing out. Not such a problem as this area is all below waterline and covered in antifoul so the fairing job doesnt have to be perfect / meticulous.

Its a good way to go IMHO, but i think one would need experience with the materials and their flexibility, and the designer has to be able to loft the profile and dart cuts.

If you wish to pull finished gelcoated topsides from the table, then the table also needs to be perfect, you cant just slap a few sheets of MDF together and expect a satifactory result. Your also subscribing to vinylester or PE resins do this aswell. Ive managed to use epoxy highbuild paints as a gelcoat of sorts and infuse epoxy over it, works well if you understand whats happening in a bit more detail...

 

[brian eiland]

Basically yes Brian, i make my own panels using foam core rather than polycore. I cant use polycore because i make the panels via resin infusion, and the cells would thus fill with resin.

Doesn't the initial layer of glass that Polycore is offering to apply to those panels (I think thru vacuum methods in a controlled manner) block the cells from being filled with subsequent resin application? Isn't this thin 'initial coat' completely cured, and relatively non-porous?

 

[groper]

Well best to direct that question to Maggie... but going by this;

But what you may not know is if we do a one time cure in our massive ovens
with a 600 gsm or 1170 gsm triax etc...you are not properly sealing off the resin with the out gassing....issues.

If we do what Atl is doing we are not really doing the right thing for people who just don't know...better.

Id say NO, it doesnt look like the core completely sealed off as it appears they have outgassing issues when they apply the skins to these panels. I can understand this as the core is full of air in between the cells. When cured in an oven, the air expands and makes little vent holes in the laminate.


ATL`s duflex panels have the same problem, there is some pinholing present in the laminate and so they recommend a squeegee coat by the user to seal the panels.

Id hazard a guess that these panels are not made in a vacuum as per the comment by a 3rd party in that PDF you showed us earlier. Id say its more likely that the panels are made with a prepreg applied to the core and cured in a heated platen press / oven or something along those lines - im only guessing tho. I was referring to vacuum infusion using just the polycore as a core itself - not the preglassed panels. Due to the open nature of the polycore, its not compatible with resin infusion or the whole thing will fill with resin and turn into a solid block.

If we assume the preglassed polycore panels are not porous, it still does not make any sense to use it with resin infusion, because again it would end up heavier and much more expensive than simply using a raw foam core...

Thus it seems to me, that one has little choice but revert back to old school, large scale wet laminating techniques if using this preglassed panel. You basically build the boat shape using the panels, bending them, torturing them etc, then once you have a hull or a deck layed out, drape over your reinforcement and go like crazy wetting it out. Once your done, youll have to fair out the glass overlaps and any other lumps and bumps you made along the way. Basically identical to a glass over ply build...

 

[brian eiland]

Infusion Grade PP Core & Kelsall Method

As previously stated I wanted to look more closely at the possibilities of utilizing PP cores vs balsa, foams, and other honeycomb materials. I am also looking closely at 'panel construction methods' where these 'panels' are prefabricated to some degree much like the kit-boat builders in NZ and Australia are using. As I look more closely at these prefabricated 'cored panels' I find that they are basically only supplied with a 'basic skin' to which each different builder will have to apply his own additional skin layup to obtain the strength he is seeking. That additional layup is done in free-stream without a mold surface. Therefore it will require additional fairing work to obtan a smooth finish coat. That additional fairing work can be very time consuming.

Contrast that with Derek Kelsall's method of producing his panels ona smooth table, and arriving at a fine finish on the outer surface of his panel. Derek is also almost making exclusive use of resin infusion to build his panels, which makes for a nice uniform panel without resin starvation, and with likely very good bonding between the core and skins.
http://www.kelsall.com/UniqueKSS/WhatIsKSS.pdf

One problem might be that Derek, and several others, insist on using only foam as a core material, particularly sense it stands up under the resin infusion process.

So I'm reading a little more closely and I discover Plascore is now making a "Infusion Grade PP Core"
Infusion Grade PP Honeycomb - PP Honeycomb

Utilizing a composite surfacing material, the open cell structure in Infusion Grade PP Honeycomb is sealed, thereby allowing the flow of resin during processing to remain at the bond line with minimal penetration into the honeycomb core. The veil provides a continuous substrate for 100% adhesion to the panel skin material. The core does not incorporate any flow paths, so a careful selection of glass reinforcements that have a resin flow path capability is required. To help facilitate a uniform flow of resin through the sandwich structure, additional pass through holes are added to the honeycomb that pierce the surfacing material at one cell and allow resin flow from top to bottom of the sandwich. Spacing of these holes is typically 4" on center.

Infusion Grade PP Honeycomb features a composite surfacing material that is compatible with most laminating resins.

 

[groper]

I read the brochure Brian, seems a step in the right direction with PP cores.

2 things,

First is it has a lower shear strength than the same density structural foam cores. But it has a higher compressive strength, which is why it does better in impact testing.

Second is the finished weight, they peirce a cell every 4 inch to allow resin through the core to the feed the tool side laminate of the sandwich in the infusion process. The brochure says the cells are 8mm dia, so those cells end up filled with resin. Foam cores can be perforated the same spacing, but the holes are only 2mm dia, this means about 16 times less resin trapped in the core- which becomes a significant amount in terms of cost and weight. I'd also worry about exotherm if using a styrene resin and gel coat, it may create spots in the finish where the open cells are. A 4 inch spacing can likely cause infusion problems as well, most go down to a 2 or 1 inch spacing to prevent fibre lockouts between perforations.

The added volume equates to an extra 370grams of resin per square meter in a 20mm thick core compared to foam- a 25% increase in core weight.

 

[groper]

I understand where you are coming from Groper. I also was hoping to have a 'finished surface' on the exterior of a vessel built with these panels. Otherwise one will always be burdened with having to fair the this exterior surface prior to final gel coating or painting

I brought this subject up before:

....and I seem to recall that they were suppling pre-glassed panels for the construction of their catamaran kit. They obtained their honeycomb panels from Maggie I believe.

I believe there is a way to pull up 'archived websites', but I do not know how at this time. It might prove interesting to view their kit building info in more detail. If I google Solitary Island 12M cat all I get is
http://www.multihull.com.au/site/www/pdf/pdfs/pacific_40_kit.pdf

oops, wait a minute here is another PDF I had saved on my computer....attached PDF
Note this quote from that document:
"The Polycore panels, using quality epoxy/glass are pre-glassed in the factory using vacuum presses producing a very good, consistent volume fraction resulting in the ultimate lightweight panel"

This is the 'panel' I wanted to use to save on the 'after glassing fairing work,....to get a 'molded finish' on the exterior.

I saw one of the only 3 solitary island 40 kits being built today. Quite an impressive boat and the kit has a modern build method and comprehensive set of plans and building instructions, im surprised they didnt sell more of these before going belly up?

Anyway brian, these kits came with preglassed structural panels - they had a dbl bias stitched laminate on all the panels from which the boat developed plates were CNC routered. So the only additional laminates required, are where the extra reinforcing is needed such as main beams, structural bulkhead cutouts etc. The rest of the panels are good to just go ahead and assemble and had only a very slight bump down the center of the panel where the glass overlap was. Otherwise, the panels were very fair and looked good, almost zero fairing provided you dont introduce any unfair curves when you bend or twist them into shape around the bulkheads - there is always some error tho unless you have some sophisticated alignment jig for setting them all up.

The hull shoes were supplied as a premade component of the kit, in infused PVC foam sandwich from a female mold, as its all compound curved / round bilge deemed too much work for an easy assemble, otherwise flat panel kit.

All in all, a pretty good kit IMHO, the guy building it is doing a great job by himself. These structural polycore panels with dbl bias on them, looked like good boat building material.

 

[brian eiland]

I saw one of the only 3 solitary island 40 kits being built today. Quite an impressive boat and the kit has a modern build method and comprehensive set of plans and building instructions, im surprised they didn't sell more of these before going belly up?

I thought is was a very professional put together project as well. I even drew up a slight modification for it to have a mast-aft option desired by a potential client of mine....that fell thru though.

...slight stern mod and aft-mast




I think they just had to face the reality that the boat market wasn't going to be much after that market crash we had here in the USA (and worldwide). It was probably going to be a big cash drain to try and slip thru the next few years until things got better.

I suspect they closed things up in such a manner that it could be restarted again, either by themselves, or sold off to someone. Even now it might be to early to restart,...in my opinion.

 

[brian eiland]

Greetings all.

I had not realized that this new core has generated so much interest!

I watched the feeding frenzy at the Sanctuary cove Boat Show on the Gold Coast this year.......when people actually saw the right core!

Most of the comments were I thought.......I knew....????

The boat manufacturers were lining up to feel the core and to see the independent DVD impact tests
and the independant DVD on the new fire rated Polycore!

And by the sounds of it you all seem to be confused with its abilities and strengths.

Are you aware that Polycore is the new generation PP core that is actually structural?
Many do get confused and call the old type of honeycomb cores Polycore!

I have even seen and heard some sales reps pulling the wool over some of the yachties with trust me this is the real structural Polycore core while waving the old type core under their noses!!!!!

Look......
they may look the same but you actually MUST have the two in your hands side by side and you will see, that they are miles apart

If you have any doubts just look at the panel at each end there is a
Brand mark...which says's
Polycore Honeycomb (TM)
next on the sheet is the manufacturer
and then the sheet will have its grade... H for HIGH STRENGTH or S for STANDARD core.

If you want to feel the real Polycore core drop me a line and I will pass you to the right distributors of the core......

The real Polycore is structural and has passed for full hull core and bulkhead construction with its testing with DNV for non survey vessels!!!!!
Certificate pending the final stage for surveyed vessels.

Genuine Polycore is equal to core cell foams and Dviney cell in strength all three will sail you home just Polycore would do it cheaper!!!
and with impact it was a top score!!!

Balsa core in impact testing failed badly the DVD of the testing showed the 15kg weight going straight through the Balsa core like it was cannon shot going through butter at the 3 meter mark you saw it fail and leave a hole that no man could plug or bail out to save the boat.

P.S

In China there is a trader selling the old type of core, and call themselves Polycore Technologies
I must make It clear that this company is not a manufacturer and has just stolen the name Polycore.

There was a lot of talk about it and at the show it was made clear that this company was a leach

This is one of the reasons why I joined your forum,
If I can assist people it will make my day!!!!!

As Multiehulls are my life and 2nd love

Cheers Maggie

I just started thru this older subject thread in review, so excuse me if I an behind the times.

Has anyone seen this subject thread (abbreviated) about the power catamaran in Thailand with water incursion to the core problems?

I'll have to find that link and post it. Ah, here it is:
http://www.boatdesign.net/forums/materials/repair-water-core-material-fibreglass-boat-56743.html

 

[brian eiland]

More Polycore info...!!!!!!!


Go to www.polycorecomposites.com
They are the manufacteres of this product....

And see the inderpenant impact testing .... !!!!
it is on their video page ..

They show a 15kg weight comming down onto the glassed panel re peatedly in the one spot bouncing as it goes!!!!!

The test is in two parts ... showing a light lay up ... and a heavyer lay up
and with the heavyer lay up it really is impressive!

you can engineer fantastic strenght into your boat as this core can be used with any glass combination....

The core used in the video is the PP8H core with the .8 shear and 2.2 compressive strenght
beware of the imitations on the market.... as they do not weld the core to the scrim the same way Polycore is welded..

The impact testing proves that!

Cheers Maggie

I have always wondered about the total integrity of this welding (fusion process)?
And secondly, I have wondered about the 'permeability' of this scrim to water ingress.??