Plyfoam Panels

[Mike]

Hi All

I am trying to find out more about a plyfoam panelling material which is sold under the trade names of Divynicell or Panglostich or Airex. They are apparently marine grade closed cell foam panel materials with properties of extreme strength in compression and shear, don't absorb water, glue well and make a very good lightweight panel with the added bonus of sound deadening.

The UK seems to be devoid of much information on these products but they are being widely used in boat construction elsewhere. I thought some of you guys may know a lot more about these materials than I do (George, Andrew E, Beachbum?) and could throw some light on the subject for me as well as others here.

Any known sources, prices, usual method of lay up, etcetera would be most welcome.

Best wishes

[Mike]

Hmm .. a bit of sunny weather and we Brits go real quiet. It must be the shock of actually seeing a blue sky and feeling warmth that does it! Ha ha. Lovely weather and I'm feeling quiet too.

Never mind my query above, guys. I have found out most of what I needed to know.

I won't bore you with details as the plyfoam panel idea is not of much interest to me now that I see it is really about building a glass boat rather than a wooden boat.

If anyone else is interested, I would suggest you might take a look here (http://boatbuildercentral.com/howto.php) and, in particular, here (http://boatbuildercentral.com/howto/foam1.php).

Best wishes

[George Waite]

Mike
Sorry for the late reply but stick this sort of question on the "Materials" section and it may get noticed earlier.
George

[Mike]

Good point, George, it's done. I sort of lost interest when I found some info on the stuff. Well, enough to know I don't want to get into using it anyways. Mind you, it's a good job I did lose interest since nobody was forthcoming - and your reply was not exactly full of information either, late or not.

Wassup mate? The humidity getting to you down there or did you get out of bed on the wrong side this morning? Incidentally, George, you don't happen to know a chap by the name of Chris Waite do you? Any relation perchance? ;)

Regards

[bowdidgemarinedesigns]

I am trying to find out more about a plyfoam panelling material which is sold under the trade names of Divynicell or Panglostich or Airex. They are apparently marine grade closed cell foam panel materials with properties of extreme strength in compression and shear, don't absorb water, glue well and make a very good lightweight panel with the added bonus of sound deadening.



G'day Mike, in realtion to Divinycell / Airex and its applications is boats, the only thing we require is Core Shear strength. The core itself is only a seperator of the laminates. The larger the gap between the lamintes, the greater it's Moments of Inertia or ablity to resist bending. The core itself provides no strength except in shear.

Comparing different cores and their shear strengths:
Product Shear Strength
Divinycell H-80 145 psi
Divinycell H-100 200 psi
Airex 94 psi
Balsa (Baltek) 432 psi
Plywood 2000 psi

On a different note, for example Divinycell, like other company's, is the same closed cell high density foam that is used in Bouyancy compartments of blocks
regards
Mark Bowdidge (MRINA)

[Mike]

Thanks for that information, Mark. Its interesting to know, even though I've lost interest in the subject for my own builds.

Perhaps the most illuminating of the stats you give is the high shear strength of balsa and plywood by way of comparison to the foam core products. Plywood is apparently extremely strong as a core, though obviously much heavier. I can now understand the reason for the use of the latter - light weight - but I am mightily impressed by the apparent strength of a plywood hull encapsulated in epoxy/glass.

It is great to have this explanation. Cheers!

Best wishes

[Rich Maynard]

I think Matt Newland at Swallow Boats uses Airex for the cabin roof and perhaps bulkhead of his BayCruiser for, if I remember correctly, a claimed 40% weight saving.

[Ricsudukai]

Having had the privilege of repairing a 'minor' soft spot on a cabin top fitting a while ago I can assure you that for balls out performance foam core construction is so far unequalled - but with even a very tiny little small minute hole or crack that allows water in an interesting thing happens. While the core is not going to absorb water, it will tend to delaminate - this happens over time, and is rather important, as foam core that is not fully bonded to all surfaces is not very strong at all, in fact it is as strong as a used tissue. Frequently by the time a part of the deck is acting obviously elastic the problem has existed for a while, and is far more extensive than remotely dreamed of. Particularly by the owner as you start grinding 3 square metres of deck off to fix one(!) screwed fitting. In a perfect world all fittings and structures are screwed or bolted through oversized plugs of modified epoxy, so any water getting past a fastener cannot possibly enter the internal core or any glass or other fibre reinforcement. Barring major damage at least. Unfortunately in the real world few fittings not originally specified have the correct method of fitment carried out, most big issues start with fittings placed on the boat by the owner or well meaning but lesser skilled workers. There is actually a lot of invisible work done on boats by the very competent - which is why you get charged the GDP of a small country to get one onboard.

Mike, you are right - it is a fancy addition to the GRP type boat building kit. I am ambiguous about it - it is just another material neither good or bad, just with it's own qualities and issues. The Farrier tri's are using it a lot lately to give very strong light hulls and amas - on a 27 footer the weight saving over the last glass over ply versions is in the metric tonnes! That's a pretty compelling advantage if you want to go really really fast.

I still like wood better. Some of the foam core sheets have :grandpa:dimples like a golf ball - which creates complex emotional issues on a personal level that are utterly meaningless to anyone not sharing my head-space, but enable me not to use it much.

[Mike]

I think Matt Newland at Swallow Boats uses Airex for the cabin roof and perhaps bulkhead of his BayCruiser for, if I remember correctly, a claimed 40% weight saving.Thanks for that information, Rich. It means nothing really, that weight saving quality. If saving weight alone was a quality then we might be better to build our boats using tissue paper - see further below.

Having had the privilege of repairing a 'minor' soft spot on a cabin top fitting a while ago I can assure you that for balls out performance foam core construction is so far unequalled - but with even a very tiny little small minute hole or crack that allows water in an interesting thing happens. While the core is not going to absorb water, it will tend to delaminate - this happens over time, and is rather important, as foam core that is not fully bonded to all surfaces is not very strong at all, in fact it is as strong as a used tissue. ... . In a perfect world all fittings and structures are screwed or bolted through oversized plugs of modified epoxy, so any water getting past a fastener cannot possibly enter the internal core or any glass or other fibre reinforcement. Barring major damage at least. Unfortunately in the real world few fittings not originally specified have the correct method of fitment carried out, most big issues start with fittings placed on the boat by the owner or well meaning but lesser skilled workers.

... .
Mike, you are right - it is a fancy addition to the GRP type boat building kit. I am ambiguous about it - it is just another material neither good or bad, just with it's own qualities and issues.Ahah, just as I suspected, it's a 'go faster' thing. That's another good reason for me to put it in the 'not interested' pile. The primary reason seems to me is its cost.

My thanks to both you chaps for this added information on an old matter. It's great to have some more knowledge and experience added to our ranks. I just love this Internet thingamajig - now that I've got the hang of using it to some limited degree. Even an old timer like me can use it to learn so much that was simply inaccessible in our younger days. It's great!

Sincere best wishes

[Rich Maynard]

Thanks for that information, Rich. It means nothing really, that weight saving quality. If saving weight alone was a quality then we might be better to build our boats using tissue paper - see further below.
Ahah, just as I suspected, it's a 'go faster' thing. That's another good reason for me to put it in the 'not interested' pile. The primary reason seems to me is its cost.

Low weight makes it easier to trail as well. The BayCruiser 20 weighs in at 450kg which isn't bad for a 2-berth boat with cabin. 400kg of optional water ballast can be flooded into two tanks, fore and aft.

With an alloy trailer it'll go unbraked behind a family saloon. Quite attractive, that.

Rich M.

[Ricsudukai]

Adding lightness to any boat adds performance, while there is much to be said for solid proven design built of timber, I also remember when ply boats were called butterboxes, and GRP boats referred to as tupperware. All materials were newfangled and cutting edge once - even hollow logs. One must guard against arrogance regarding any material, as I said - all materials have pros, and cons.

I built a chair once using only hand tools - it was really satisfying, but it takes old world attitudes to time. If you want a genuine hand built anything it will cost many times the mass produced item, and most simply don't want to pay. There is a lot to be said for strip laminated hulls, easy to build, a little harder to setup, and messy - but a well designed stitch and glue hull is a revelation as far as speed and simplicity are concerned. The sad truth is that it is just as toxic to work ply, epoxy and purely synthetic panels - regardless of appearance. If you are to build using solid timber and natural materials in a deeply traditional way you can avoid many of the nasties, but be prepared for the build time frame to be many thousands of hours. And the learning of the traditional tooling and timber working skills will take a fair commitment too.

We have a fantastic ability to build and operate brilliantly conceived and designed boats, and we have such amazing things at our disposal to help - motor vehicles, power tools, synthetic glues and coatings, the interweb, beer, beer fridges, full colour magazines stuffed with obscenely talented people and their works to keep us humble.

What a wonderful time to be alive!

[Mike]

Ric, that is just about the most refreshing post I've seen on this website. Excellent! Brilliant, in fact. Well done - and all power to your elbow, mate, as you use those two examples you give above that go together so well - beer (well, lager to be more precise) and an ice cold beer fridge! Bet you keep your beer glasses in that fridge over there in the land Down Under. I always did. Improves the taste in some mystical way so that you don't know quite which brand of lager you're drinking coz they all taste the bloody same when cold enough to enjoy.

Great post, Ric, and worth some additional rep, which is done. :approval:

[Ricsudukai]

Why thank you! :cloud9:

You want to be careful - debating beer (and brothels) is high risk with Aussies. :)

I actually drink ales, particularly a brand by the name of Coopers. The dumbing down of the brewers by the two biggest players leads to a lot of 'formula' beer - or over priced yuppie stuff lately in Oz. But I am very pleased to report that there is a wonderful resurgence in micro breweries as a reaction to this, and some of these are truly wonderful! (I am trying as many as I can)

I learnt to make beer from my Grandfather, we used to do the lot, crack the barley, make the wort, add more hops and secret things, let fester and bottle several dozen at a time. You're talking to someone with a fair interest in zymurgy, and the gut to prove it.

Apart from beer, the best thing to enter the shed with is a good attitude. Nothing we do is new in the sense that someone else has already done it, so we can cherry-pick the best bits and methods, and learn from others in a mostly successful attempt to avoid the mistakes.:toast:

[George Waite]

Ric
Tried some Coopers a couple of years ago on an Aussie survey ship, a very good ale! Had an Aussie friend visit recently who was quite surprised to find it in our local supermarket.

[jwboatdesigns]

Ah! Chair making! There is a trade in England known as "chair bodging" . Hand turning the legs, backs and braces for Windsor or bentwood chairs, Wikipedia has quite a lot on this trade. The lathes that were used by the way were whats known as "pole lathes" which were foot powered.

Light weight? I think it was Henry Ford who said to his design staff, "Simplicate and add more lightness".
It still applies today, and too many people forget that.

John Welsford

[Mike]

There was a recent series of very interesting TV programmes hosted, I think, by Monty Don that dealt with several of the older crafts like stonemasonry, roofthatching, stained glass work and the like.

One was dedicated to the subject of what you call 'chair bodging'. The pole lathes of which you speak were used for precisely that, turning green wood to make chairs that were joined without the use of glues or fixings of any kind. They simply relied on the perfect mating of wood components into holes drilled to the appropriate size. Amazingly skilled craft. Looked easy until the three 'trainees' had a go.

I particularly enjoyed that one - and the one on thatching. Brilliant, though not my kind of work really.

Old Henry seems to have known what he was doing with respect to building cars. One wonders where the offspring went wrong after his eventual demise. With the head start he gave 'em you would think the biggest and best manufacturer today would be Ford but it seems the Japs and Germans did just a tad better. So much for losing wars, then. :rolleyes:

[Ricsudukai]

Hi John, I've been lurking on your forum for a bit now - rather taken with AWOL (grovel grovel).

Chairmaking - yes. One of the highest ever recorded outputs of furniture came from those bent wood construction, cheap, strong chairs. The makers used to wear a hole in the skin over the breastbone by the constant leaning on the drill brace when boring the holes for the legs etc.

The way any timber joint is cut is actually very important in solid timber - a correctly cut and prepared mortise and tenon will be very difficult to separate if dry fitted, almost impossible in fact - even with no glue. The joinery I was taught relies very little on glue, rather the timber itself and it's characteristics. The commercial fact is though that few have the budget - or even want to spend that level of money on true joinery. Dowels - are not joinery, biscuits are however very good for connecting boards to make larger panels, but they are not a mitre joint device. Still, Chippendale the senior would have loved computers and machine tools - the limiting factor commercially today is the time it takes to teach the fine skills of timber working - it is so much easier to build a machine and hire semi-skilled labour to feed it and press the buttons, look at commercial boat building over the last few decades.

It's a good job we have interesting designs, by interesting designers that can be built with not a lot of effort and time at home.

Otherwise we'll all be stuck with GRP or rotary molded plastic bottles with a pointly end and told they are better somehow than a light, strong, graceful and satisfying wood boat.

Better get off the soap box - I'm starting to rave.

[George Waite]

Ric
Your point is well made. It seems the responsibility for the preservation of real skills has fallen in to the hands of amateurs (in the financial sense).

[Rich Maynard]

There was a recent series of very interesting TV programmes hosted, I think, by Monty Don that dealt with several of the older crafts like stonemasonry, roofthatching, stained glass work and the like.


Can't believe you forgot blacksmithing...sigh...

[Mike]

Well, I didn't forget it really, Rich, as it would fall under the catch all phrase 'and the like'. Sorry, mate. I did watch the one on blacksmiths. That was quite a giggle at times. It ain't as easy at it looks, is it?

I used to love doing metalwork at school back in the sixties but my first love, even then, was wood working. Comes of having a highly skilled father who worked wood all his life. Don't quite understand why I became a 'Driver - Aeroplanes' but am making up for it now.

Best wishes