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Author Topic: Surfacing a foam boat  (Read 1134 times)

aamcle

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Surfacing a foam boat
« on: July 21, 2018, 07:43:25 PM »

If all goes well I hope to be starting a scratch build soon, I will be building out of foam which is fine but I will have to put some sort of tough shell on it.
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This is were it gets complicated, I would prefer not to use fiberglass or epoxy resins I've seen "poor man fibreglass" Titebond impregnated cloth and things done with paper and varnish.
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Even after much reading I'm not sure what is the best way of producing a tough hull and avoid polyester and epoxy resins, I'll use them if I must but... 
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Any suggestions of links would be much appreciated.
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Many Thanks.          Aamcle
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Ralph

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Re: Surfacing a foam boat
« Reply #1 on: July 21, 2018, 08:46:23 PM »

Several years ago I built a hard chine fast electric round a foam core. I skinned the foam with very thin (0.8mm I think) birch ply stuck on with Copydex impact adhesive which didn't react with the foam.  I did coat the ply with epoxy resin thinned with iso-propanol alcohol to seal it but a more conventional paint job would maybe do if you want to avoid resins.


If you're looking at a more rounded hull, perhaps diagonal planking over the foam with the thin ply?


Hope this helps
Cheers
Ralph
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Andyn

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Re: Surfacing a foam boat
« Reply #2 on: July 21, 2018, 08:57:40 PM »

Brown paper and pva works beautifully and is very tough, make sure you seal it well. Used to have a couple of planes from Mainlymodels (formerly in Hitchin, when Barry used to sell kits) and they were super tough.
The obvious choice would be West System epoxy and cloth though :-))
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aamcle

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Re: Surfacing a foam boat
« Reply #3 on: July 21, 2018, 09:08:35 PM »

Thanks All.




Aamcle
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minimariner

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Re: Surfacing a foam boat
« Reply #4 on: July 21, 2018, 09:49:55 PM »

Aamcle,

             Have a look on YouTube showing covering RC aircraft
            with coloured parcel tape.

                  https://www.youtube.com/watch?v=PbyVGfB1oCg

                Bryan.
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Howard

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Re: Surfacing a foam boat
« Reply #5 on: July 21, 2018, 11:21:20 PM »


cover the foam with a pair of your wife's tights or maybe one of her stockings acts as a skin,
 Regards Howard.
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unbuiltnautilus

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Re: Surfacing a foam boat
« Reply #6 on: July 22, 2018, 08:52:37 AM »

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JimG

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Re: Surfacing a foam boat
« Reply #7 on: July 22, 2018, 11:05:51 AM »

Eze-cote is basically a water based varnish originally used for floors. It works as a finishing coating with or without fabric but does not give as hard a surface finish as epoxy resin. It is more easily scratched or dented than an epoxy or polyester resin.
Jim
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Re: Surfacing a foam boat
« Reply #8 on: July 22, 2018, 12:45:05 PM »


I think that you will need to decide what you mean by "tough".


Foam is easily damaged by contact with sharp edges etc and putting any coating - stockings, neat epoxy etc - does make it less liable to damage but does not make it "tough" within any definition of sharp object damage that I would use.


If you want it less susceptible to damage you are talking about covering with ply or better sheathing with proper fibreglass woven cloth & epoxy.


I have never seen any calibrated test results for sharp object penetration damage.

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Netleyned

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Re: Surfacing a foam boat
« Reply #9 on: July 22, 2018, 01:38:38 PM »

cover the foam with a pair of your wife's tights or maybe one of her stockings acts as a skin,
 Regards Howard.


Fishnet Stockings are the best for trawlers %% %%
Ned



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Howard

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Re: Surfacing a foam boat
« Reply #10 on: July 22, 2018, 07:02:28 PM »


lol trust you to think of that Ned, Cod Heads always think out of the box lol hope to see you down at the lake soon Ned.
                               %% Regards Howard.
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ballastanksian

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Re: Surfacing a foam boat
« Reply #11 on: July 23, 2018, 08:03:00 PM »

Ron Rees has done one or two articles on cladding foam boats with tights and resin or varnish.
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RST

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Re: Surfacing a foam boat
« Reply #12 on: July 27, 2018, 10:26:51 PM »

Perhaps it goes to show how few folk pick up Model Boats mag these days?  Per chance there is an article from Graham Ashby (very active on the Model boats forum) this very month who made a model from foam and decribes very well how he glued it together and covered it.  I know allot of folk don't see the value in mags but I still do and they're worth every penny?

For me personally I tend to build in balsa / basswood because I can cut it with a knife and it sands very easy -I work in my flat on the coffe table in front of the TV!  I've never taken Glynn Guests advice before now and used tissue paper as a covering for a full hull (I've only done it for small fittings like lifeboats) but I did this time and used it "paper mache" style using Deluxe water based "Eze Dope" which is a delight to work with and fills allot of gaps / low spots by addition of another "bit" of tissue to save filler.  Personally, I bought a pack of ZAP Z-Poxy a few years ago which has done 3 or 4 hulls now, and for the same cost of a pack of coarse tissue -I got a pack of 80gsm fibreglass cloth the other day and went back to covering everything in that.  I have not had the guts yet as a single man to buy a pair of tights in Tescos yet to try.  Neither the Eze Dope or Z-Poxy have any discernable smell (the Z-Poxy is slightly sweet but no more offensive than some emulsion paints).  Eze dope wash the brush out -Z Poxy throw it away.  Both sand incredibly easy but I feel the Z Poxy will last longer and is the better choice for wetted parts.
I would say to carve a foam based hull then cover it you may have taken a slightly harder route to start with as a beginner, but not the hardest.  But there is nothing wrong with your method and lots of folk round the world build this way (US guys seem to love it).  You don't necessarily need a hot wire cutter (if you do -look-up model rail forums as they just love them for EPS and XPS).  For me as an ex-model railway dabbler I found a very sharp kitchen knife (Sabbatier), or the blade pulled from a retractable break-off knife worked pertfectly while everyone else was fretting about mess with woodsaws etc, I had virtually no mess and clean cuts.  Untill you sand of course and that will always create dust.

.....Bear in mind also I've only been modelling 30 years now so expect me to be stick in my own personal ways.  I think there's plenty out there on 'tinterweb on this kind of stuff.  You mentioned you might have a plentiful supply of foam so the best bit about modelling is to try for yourself -because if itworks for you it won't for someone else and vice versa!!!!  Don't be afraid to try things yourself because that's how you learn.
Cheers,
Rich
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aamcle

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Re: Surfacing a foam boat
« Reply #13 on: July 27, 2018, 10:49:26 PM »

I have the parts for a hot wire cutter either to hand or on order.


I'm going easy on myself my first build will have a hard chine  hull essential flat plains so I'm going clad it with this ply then possibly diagonal plank it just to learn how to do it. If I don't do well enough I'll paint it.


I've been reading up on longitudinal planking  it seems quite tricky but at least there are good walk throughs so far I've found little no diagonal planking.




Atb.        Aamcle.
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