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[Leaky]

we manufacture office doors where i work and i have access to a virtually unlimited supply of 3mm MDF sheet.Is this stuff a bad choice for internal use in a hull? Can i use it for such as non structural work and superstructure building and what can i do to make it more suited for marine use?(if possible) :-\

[dougal99]

I used MDF for the keel and frames for a Brittany trawler. I have had no problems with the frames but despite covering the keel in resin, undercoat, paint and varnish I have had problems with water ingression causing the MDF to expand badly. I have recently repaired the keel, by cutting out the swollen area and replacing with plywood and car body filler, for the third time. If this doesn't work its permanent dry dock.  :'(

Moral: don't use MDF for parts/areas totally submerged.

HTH

Doug

[Peter Fitness]

As you work with MDF, you will know how it hates water. You could use it internally, but it would need to be THOROUGHLY waterproofed, because the slightest amount of water will cause it to swell. My own method of waterproofing any timber I use in a hull is to coat it with fibreglass 2 part resin, both inside and out, which I have found to be extremely effective, and since using this method, I have never had a timber hull leak. Because we live in a warm climate, I reduce the amount of hardener, which slows the setting time and allows me to complete a job before the resin starts to harden.
I'm sure many on this forum will have other ideas on the subject.
Peter

[Peter Fitness]

I might also add that I have never used MDF in model boat construction, all my scratch built hulls are made from plywood.
Peter

[barryfoote]

I agree with Peter......DON'T DO IT......Asking for trouble and when other, better and cheap materials are around, simply not worth the risk or effort..

Barry

[HS93 (RIP)]

All its good for is frame work for a mould to make a fiberglass hull, and as you will know working with it having to Ware a mask before cutting or sanding it is not a nice way to work for a hobby, wet MDF just falls apart.

Peter

[FullLeatherJacket]

Makes a good drip-mat for your beer mug/wine glass, and is excellent stuff for model carrying boxes and stands as long as you give it a few decent coats of varnish.....but as a construction material for actual model boats, forget it. Papier mache would be more durable!
FLJ

[nhp651]

I've used it in bread and butter construction for making a plug for GRP moulding, which works fime, but it has no real structural stregth for plank on frame models( frames) as you just can't nail/pin into the end grain with any decent purchase for the planks.

[Bradley]

Another thing to remember about MDF is that it is strongly suspected that the dust is a carcinogen (it don't do you no good :'()
Derek.   

[Roger in France]

Use a good thick piece as a building board for cheapness and straightness but it must be thick to retain the flatness.

Roger in France.

[Leaky]

Thanks for the info lads ill not use it we do seem to have a large stock of real wood veneers that have taken my eye

[malcolmfrary]

Papier mache would be more durable!

Model yachts between the '20s and '50s.  And I recall a series of articles in the late '50s about using gummed paper strip.  (Rubber powered destroyer and suchlike, probably Model Maker magazine)
Due to its basic weight and poor strength to weight ratio and problems sealing it and keeping it that way, its best avoided apart from using it for boxes and stands.  The veneer will probably look better anyway.

[Colin Bishop]

Gummed paper strip is fine if properly treated such as impregnating it with shellac or similar and painting. I have built several models using GPS as the cladding with no problems whatsoever. Don Brown, who many people will know as a top class modeller, used to build his entire hulls with gummed paper strip and they never gave any trouble. It's a nice material to work with.

Colin

[Bryan Young]

Gummed Paper Strip, I "planked" the plug of my "Discovery" with it and the final hull really does look like a timber planked hull due to the sort of "graininess" in the paper. BY

[SimonO]

Hi Guys

I know the faults associated with MDF and that resin coating only works if the outer covering of resin is not breached allowing water to soak into the MDF below, however my second boat (a VIC Coaster) was built from 10mm MDF sheet from a skip. A tip I was given was to get a tin of marine varnish (although I have also used cellulose dope) and thin it down 50/50 with thinners, then soak the hull thoroughly through with the mixture. I did this 3 or 4 times prior to painting and have never had any issues with water swelling the fibres as the thinned varnish soaks in, my coaster is now 9 years old and sails most weekends, check out



I Feel its not always the material thats the problem its how you treat it.

Regards

Si

[SimonO]

Hi Guys

Just found this taken during building, in case proof is required....

http://s136.photobucket.com/albums/q196/sifromdevon/?action=view&current=ModelBoat2039.jpg

I cut the centre section away after plating the outer hull with 3mm marine ply..

Regards

Si

[barryfoote]

Si,

Proved us all wrong amigo. She is a beauty. Do you have any more details and photos of her. She is just the kind of model I love.

Barry

[SimonO]

Hi Barry

Thanks for the nice comments, 'Titan II' is scratch built and is 46" long with a beam of 14" and is built primerily from scrap, its a show boat really built to entertain and not as a scale boat so there are some conflicting scales. I have a few shots taken at a show we did for the National Trust, check out

http://i267.photobucket.com/albums/ii307/ilfracombeboats/Elsie%20Roff/DSCF0017.jpg
http://i267.photobucket.com/albums/ii307/ilfracombeboats/Elsie%20Roff/DSCF0018.jpg
http://s136.photobucket.com/albums/q196/sifromdevon/?action=view&current=ArlingtonShow2007002.jpg
http://s136.photobucket.com/albums/q196/sifromdevon/TITAN%20II/?action=view&current=DSCN2954.jpg
http://s136.photobucket.com/albums/q196/sifromdevon/TITAN%20II/?action=view&current=DSCN2950.jpg

If you want I will take some close up detail shots for you, thanks again

Regards

Si

[barryfoote]

Si,

Photos are always welcome........Don't forget our number one rule....photos, photos and more photos...

Barry