Epoxy Foam core....

[JJ.windspeed]

G'day! yep located d/u if you didn't guess~

Have been reading through various threads on composite materials; cores and skins etc. in this forum for a while now.

I am currently building a prototype 'type catamaran' for the purpose of a world wind speed challenger and all-round thrill seeker sailer.

But first need to get the prototype built and tested to see if concept actually works. The project has been 10 years in the making, and recently due a bout of unemployment, have built a boat shed with spare time (1st 6 months of 2011), and have now started on this unusual sail craft.

I love being in the shed very much, beats the office any day! I feel I have completely missed my vocation in life having spent the last 6 months on the tools, on the boat, in the shed.

The prototype sailing craft will be 14' in length, be built using epoxy f/g.
My intention is to commercialise project after fully tested so need to cap costs at the outset.

The problem I'm coming up against is the materials are kinda expensive! PVC foam (6-10mm thk) cost out at $1000 so dropped this completely and will use 2x bi-directional glassed for main shell with 2x extra layers 500mm wide for bracings at spars giving total 4 layers bi-directional, this should do for the prototype.

My initial question is about 'foaming epoxy', which I believe is used for aircraft wing cores, also boat rudders and centreboard cores.
Nobody seems to know about the stuff at the regular boat composite outlets: "never heard of it" is the constant reply I get.

Need to find what the foaming agent is and where to get in Sydney (havn't called Garit just yet)

I am wondering if anyone in boatdesign.net have used it for a core material? I'm thinking it would make excellent structural core that could be poured into mold to get a basic blank hull shapes ready for laminating very quickly, or used in flat laminated sheets and cut into shapes; perfect for mass production. Could be used to replace self pour foaming polyurethanes (which I would be using on the project).

Here are some found links for epoxy foam:
SP-High Modulus (Australia)
Youtube link showing pouring epoxy foam
Matrix composites again pouring..

Any help or advice greatly appreciated.

[Herman]

I have used both the Ciba system from the youtube video, and the Sicomin stuff.

Couple of remarks:

-the youtube video shows a regular epoxy, with foaming agent added to it. You see a lot of popping bubbles, you do not want that.

-the maximum amount of foaming agent we managed to get in, and get decent foam, created a foam of approx 150 kg/m3, so quite heavy compared to PVC foam.

-To obtain decent properties, the stuff needs to be postcured.

-It is about impossible to cast nice flat sheets, unless you create something like a mould. The foam is hardly bendable afterwards.

-In general, epoxy foam is more expensive than PVC.

-your quote on PVC foam seems to be on the high side. How much foam, and of which density and thickness do you need? (So I can at least give you an idea of what you should pay)

[JJ.windspeed]

Divinycel 8 x sheets = two hulls. 3 x 2.2m sheets 6mm thk and 10mm thk. anywhere from $110 to $180 per sheet plus tax. plus delivery, or haul my ass across Sydney metro peak hour to pick up.

And problem with using this stuff on 80mm rad top deck curving, apparently its brittle stuff and snaps easily.
Transoms & structural = clegycell (I think its called) even more expensive! so looking to do some epoxy foam work.

Thanks.

[Herman]

klegecell usually is cheaper than divynicell... Quality is all roughly the same.

Over here standard prices for 80 kg/m3 PVC foam are:

6mm: 20 euro / m2
10mm: 28 euro / m2

3x 2,2 m2 sheets 6mm: 135 euro
5x 2,2 m2 sheets 10mm: 308 euro

So you can do the math...

[tunnels]

If you are only building a plug /boat why do you want to use epoxy foam ? You are wanting to use some of the most exspensive materials on the planet so to speak just to build a plug /boat !! what a waste of money !!

[cor]

If you cannot afford the price of the foam there is no way you can afford the rest of the boat.

Have you figured out what the sail and rigging are going to cost, how about the rudder and steering hardware. Are you going to paint the boat, they don't give that stuff away either. Do you need a trailer to move it around?

The bare hull is just one small (in a financial sense) part of the boat.

C.O.

[CatBuilder]

Originally Posted by JJ.windspeed

And problem with using this stuff on 80mm rad top deck curving, apparently its brittle stuff and snaps easily.

Either strip plank a tight radius...




or...


thermoform your foam around the bend...

[JJ.windspeed]

I repeat My initial question is about "epoxy foam" please keep replies on topic for and about this question.

Fibreglass is cheap epoxy resin is reasonably cheap. The polystyrene form is built, ready to have the glass draped over for the outer shells.

Need to decide about structure.

What is the foaming chemistry going on to make the resin bubble? Has anyone got specific information about this stuff.

Thanks.

[CatBuilder]

Originally Posted by JJ.windspeed

I repeat My initial question is about "epoxy foam" please keep replies on topic for and about this question.

Ridiculous. The post I quoted made it sound like you were having issues with normal foam cores because of an 80mm radius.

You said the normal foam is brittle and snaps easily.

I posted my comment so you could be aware that normal foam cores don't have to be brittle or snap easily when bending to an 80mm radius.

Hardly off topic, as YOU brought it up!

[JJ.windspeed]

OK m8 leave it at that then eh.

[tunnels]

In the bottom of the hull up forward of the yachts we were making we had a tight 75 mm radius tapperiing from the very nose, as it went aft the radius got bigger quite quickly . We tried to heat the 20mm hi density foam but there was no way it was going to go such a tight so back to the thing tank of what we had done in the past on another job that worked well . A 100mm angle grinder with a fine cut thin saw blade and sliced the foam in radial cuts the length of the foam sheets making a long wedge shape . The slice cut went close to 15 mm deep into the sheet leaving 5 mm of uncut foam .
I did not want to see or exsperiance any kind of material print though to the gel coat outside so the 5mm of uncut surface went towards the outside against the single layer skin of 600 gram double bias glass , The inside closed the cuts and left a small place at the bottom of the cut that was able to be filled with the resin and bleed out the air when the sheets were bagged into possition and stuck perminately on 300grams of csm and resin . I took one guy about 30 minutes to purfect what had to be done and work out the shape of the sheets for that part of the bow each side , we even made port and starboard panels and becasue there were 8 boats to be made all the same we made all the sheets in one sitting in just a few hours after we know what had to be done .
I feel heating is not a good idea when trying to get a tight radius , the foam we noticed went quite brittle and broke quite easy once it cooled . If you are making lots of the one thing you could try just using thin foam sheets with resin between and wrapping it like laminating sheets of bendy plywood ,bag it and wait till its gone hard .

The secret to what mades all this work 100% was the 5mm of uncut foam that did not allow the resin filling the saw cut to shrink to much and print when it went hard and cured !.
Plus the narrow width of the teeth on the small saw blade we used .
With the shroud covering the blade and a small piece of steel tack welded a wooden block the correct thickness was masking taped in place to form a deepth gauge . !!
Works a treat and have used this system many times !!


I have pictures in my library of things but need to search and find in my 2007/8 files .

[groper]

M8, you've already been told the epoxy foam is mOre expensive and heavier than PVC foam, so why are you still interested when you have cost concerns? The only reason I see is for its pour ability , of which I still fail to see a benefit to in boat building... Maybe only a few small uses etc

[sabahcat]

Originally Posted by cor

If you cannot afford the price of the foam there is no way you can afford the rest of the boat.

Bollocks
I couldn't afford foam for my last cat as it would have added 20% + to the cost of build.

Yet build a boat I did

[Herman]

Unfortunately this thread went no-where.

Epoxy foam has its merits in making rudders and paddles. And many non-marine products.

[CatBuilder]

Here's one as well:

Ampreg F230-1
Three-part Foaming Epoxy System
(resin to hardener mix ratio 100:23 by weight)
Three-part foaming epoxy system which uses Ampreg 21 hardeners. Foam expands approximately 4x
by volume to create a foam of 220-250kg/m2.
Exact foaming density depends on moulding restraints and temperature.
Product Availability
Resin Size Order Code
14.5 kg Resin F113-007
Hardener Pack Order Code
3.33 kg Slow F121-037
3.33 kg Extra Slow F121-038
(Hardener pack consists of 3.33 kg Hardener with 0.2 kg Foaming
Agent and 10cc Syringe)