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[carlmt]

Hi all,
As some of you may be aware  , I am in the process of producing our first ferry plug - and, my god, it takes such an age to get it just right .

I am now approaching the stage where I will be wanting to cover the whole plug in a filler, to sand down smooth, mark out openings and attach protrutions to be included in the f/g hull.

The plug is made from ply formers filled with a pink high density insulation foam (and some expanding foam in areas where I just couldnt get the pink foam satisfactorily).

I have read that car body filler (P38) is popular, but this is a fair sized boat (1220mm x 200mm) and would take quite a few tins to cover methinks.

Are there any other fillers, such as Polyfilla or such like, that would do the job as well, but be a little easier to apply? I am thinking that P38 requires mixing and the stuff goes off so quickly that it becomes difficult to apply.

Look forward to hearing from you all as and when.........
Cheers,
Carl

[Norseman]

Hi Carl

I'll ask Duncan (arrow5) I think he uses/has used foam. I'll pm him, he's a helpfu guy to know anyway.

Dave

[andyn]

Pm sent

[carlmt]

Cheers Dave - thats kind of you, look forward to hearing from you soon 

Andy - PM replied to 

Carl - feeling more trepidatious as each day passes and the time draws closer to creating the mould 

[Arrow5]

Covering a hull plug that size with car filler paste is the normal route I believe, however in the small models I`ve done I covered the foam with brown paper (put on wet using wood glue, Titebond II) then epoxy resin without glass. Car filler can then fill any small imperfections. Whether this would be good enough I don't know. The main thing of course is the finish and waxing of the plug.  Maybe professional hull makers might offer some assistance.  I fear that the car body easy sand route may be the answer, or someone in the car body repair business could offer trade/bulk amounts rather than Halford size tins, hint  Sorry I cant be more specific, my largest plug was a 24" Sea King helicopter.

[TailUK]

Hi all,
As some of you may be aware  , I am in the process of producing our first ferry plug - and, my god, it takes such an age to get it just right .

I am now approaching the stage where I will be wanting to cover the whole plug in a filler, to sand down smooth, mark out openings and attach protrutions to be included in the f/g hull.

The plug is made from ply formers filled with a pink high density insulation foam (and some expanding foam in areas where I just couldnt get the pink foam satisfactorily).

I have read that car body filler (P38) is popular, but this is a fair sized boat (1220mm x 200mm) and would take quite a few tins to cover methinks.

Are there any other fillers, such as Polyfilla or such like, that would do the job as well, but be a little easier to apply? I am thinking that P38 requires mixing and the stuff goes off so quickly that it becomes difficult to apply.

Look forward to hearing from you all as and when.........
Cheers,
Carl

I've done that sucessfully with GRP moulds using Polyester and Epoxy resins but you really have to go to town with the mould release.  P38 is polyester based so will stick to polyester gelcoat with avengence, unless  the mould is throughly treated.  Honey Wax and PVA release agent are good. 
       I've also been toying with the idea of covering a plug with aluminium foil duct tape to give a fine surface and replicate plating this, hopefully, along with mould release should give a nice finish inside the mould.

[Arrow5]

TailUK, Yes I thought of the ally duct tape for a finish on Dave`s proposed Kalakala until we discovered that it was not an alloy bodyshell but painted with silver paint. I wonder if card or styrene sheet plating might be better. The ally tape I have has a thick adhesive that might react one way or another with the the resins and waxes.

[andyn]

Styrene will be dissolved by the styrene in the gel coat

Andy

[TailUK]

TailUK, Yes I thought of the ally duct tape for a finish on Dave`s proposed Kalakala until we discovered that it was not an alloy bodyshell but painted with silver paint. I wonder if card or styrene sheet plating might be better. The ally tape I have has a thick adhesive that might react one way or another with the the resins and waxes.

 I honestly think the ally tape will work after it been waxed and PVA'd. The old standard Brown paper parcel tape is always an alternative.

[Arrow5]

Styrene will be dissolved by the styrene in the gel coat

Andy

  How about epoxy ?

[Arrow5]

I honestly think the ally tape will work after it been waxed and PVA'd. The old standard Brown paper parcel tape is always an alternative.

  I was wondering about heat affecting the adhesive on the ally tape. Brown paper parcel tape is very thin for detail plated ship hull I think, one coat of paint and it could be gone. I use brown wrapping paper, comes in various thicknesses and shrinks when dry leaving an egg-shell finish.

[CF-FZG]

I've seen 'Plaster of Paris' used to 'skin' a foam plug to get a smooth surface before.

Follow this with an epoxy/glass skin for durability.  Then surface detail put on using many various methods.


Mark.

[Circlip]

I think it was Hermill using Alloy duct tape to simulate hull plating on a sub he was making the plug for. As you're going to have to use wax and possibly a PVA release agent on the plug, the high bond strength adhesive normally used on this tape shouldn't surcome. Plaster of Paris is a good easy sand filler, just don't bang it about after finishing.

  Regards   Ian.

[Subculture]

I've made two plugs using foam and filler. I've found it's a quick and inexpensive method if the shape is complex, although for simpler shapes I prefer traditional wood or plastic construction.

The first attempt I used polystyrene foam, two coats of PVA glue to act as a barrier for the polyester filler, and then added the filler. Oil paint will also serve as a good barrier coat.

This worked BUT, the filler lacked strength, so I needed a very thick coat of it if the slightest ding wasn't to damage the master.

That lesson learned, for the second foam fantastic, I used polyurethane foam (the yellow stuff you find used for loft insulation). You can apply polyester resin directly on to polyurethane foam, so I slapped on two layers of 300 gram matt and resin. Once that was cured, I then used polyester filler to get a smooth finish. This plug was much tougher.

If you use epoxy resin, then you can glass straight over any foam, it won't melt it like polyester resin does. Also using self-adhesive tape, aluminium or plastic is a very good way of getting plate detail onto your master. The heat from the catalysed resin is unlikely to cause any issues.

[nemesis]

Plaster of paris is too course grained to have a good surface plus the fact that you have to wait until the thing loses its moisture, which takes ages. Made a 66in hull plug in plaster of paris, in a night, it took about 6 months to dry enough to work on, very messy as well.
           Nemesis

[colin]

What happened to my posting must have been there as i had a pm regarding it
Colin

[Nige52]

I can only speak as an ex canal boat and trailer designer/builder but....
We built all of our plugs from 1/2 and 3/4" MDF, all cracks and joins and gaps were filled with standard car body filler then sanded down when dry. When we were satisfied that the plug was about as good as we could get, we sprayed it with high build grey primer, flatting it down with wet and dry in a bowl of warm soapy water, then sprayed it again, and again.....until we had a gloss finish on the primer.
When this was done, we then sprayed the hull with commercial quality 2 pack high gloss paint, maybe several times, until you could literally see your face in it. Then when it was completely dry, we then polished the whole thing with Mirror Glaze mould release wax, not once, but maybe 15 times or more...because even though you polished it off, the polish always left a film, only microns thick, so if you polished it many times, the surface would build up a high gloss protective layer.
Then, and only then, did we apply the first coat of gelcoat.....
Here are a couple of pictures of the boat we built and showed at the 1990 International Boat & Caravan show at the NEC, Birmingham. The boat is a a 24' canal cruiser which we named the Tristar 24. The camping trailer is my own design which was the forerunner to modern 'Halfords' type trailers, at the time there were only alloy box trailers knocking about...

[Nige52]

A few more 

[CF-FZG]

Plaster of paris is too course grained to have a good surface plus the fact that you have to wait until the thing loses its moisture, which takes ages. Made a 66in hull plug in plaster of paris, in a night, it took about 6 months to dry enough to work on, very messy as well.
           Nemesis

I'm not surprised it took so long to dry if you made a complete plug from it.

Please read my post again.

I said you put a skim of PoP on it and afterwards you cover it with epoxy/glass.  From there you can do the regular finishing and detailing.


Mark.

[Talisman]

Hi Carl,

If you remember we had a conversation regarding the manufacturing of plugs ..

My concerns are (again)  - Expanding foam is not a great product for plug s as it is temperature sensitive .. i.e it contracts and expands easily.

Foam is less dense than the ply ribs so sanding down to the ribs will leave witness lines either side ... no matter how much work you put in.

I'm assuming the ribs haven't been cut to allow a surface thickness so the surface to be applied will need to be thin? Difficult to give strength to the plug in thin layers. Epoxy is probably going to give the best thickness to strength ratio?

Personally I'd have used a harder wood than the ply ribs so that it was only the ribs needing filler to eradicate the witness lines.

Or and this is at the risk of self advertising send over you drawings and have the plug cnc cut. ... may prevent premature hair loss ? and less weight in your wallet, may prevent back problems but still hurts      :)


Like i say feel free to call me.

Regards,
Kim

[carlmt]

Hi Kim - hope you are keeping well?
Remember the conversations well, and remembered your advice re the ribs.
The whole, solid, plug is some 2 to 3mm 'smaller' than would be the finished article.  The idea is to cover the whole plug in a filler, then sand smooth, etch on the cut-outs/openings etc then apply the paints / wax / releasing agents etc. etc. etc......... The filler will eradicate any evidence of the ply formers. Really, the solid foam is only to give the hull 'shape' and support the filler.

The use of expanding foam has been kept to the absolute minimum - only where the ply ribs were too close together to insert solid foam (a mistake that I dont intend to repeat on the next boat!!!) and is only in a few, isolated, areas.

As for strength of the plug, as you can see from the photos on the build topic, I have probably over-done it with the block foam : the plug is now one solid lump!!!! Probably used twice as much foam as needed............. the plug doesnt flex or twist.

As for having the plug cnc cut - do you mean you can now cut a whole 3D plug in one go? No more frames? If so, that must be expensive - that is the sort of engineering that full sized shipyards employ when building scale stability models of proposed new ships.................or have I mis-understood?

So far, so good - I am pleased with the way it is looking at the moment.........It was your advice and warning about the 'hungry horse' ribs that made me cut all the ribs some 3mm smaller than what would be required on the finished hull - cheers Kim 
Carl

[Talisman]

Hi Carl,
Did you have a note pad at the phone ... i only just remembered the Hungry horse saying lol


Simple reply to the CNC cut plug is yes .. I can do it. ... might not be as expensive as you think!

I have attached a few pics of results of my latest efforts... server wont allow me to post many pics but you get the idea im sure.
The blue foam is just a small trial plug .. we use composite materials for production plugs.

Regards
Kim

[carlmt]

Good heavens Kim - now THAT is impressive!!!!!

Exactly as I imagined - but didnt believe possible / affordable for the hobby market.

You have now piqued my interest here (too late for the current boat) for the next one.

What sort of drawings do you need to do this - I imagine they would need to by 3D (Delftship type) wireframes? At the moment, I have only worked in 2D..............

I can see Flo and I taking a holiday in sunny Scotland in the spring next year...........................and you getting a visitor!!!!!!!!

That sort of plug making can save a vast amount of time and improve on accuracy........ Thanks for the heads-up friend - food for thought as always.........
Carl

[Talisman]

ribs.
It was your advice and warning about the 'hungry horse' ribs that made me cut all the ribs some 3mm smaller than what would be required on the finished hull - cheers Kim  
Carl

Hi Carl,
If you have 3mm to spare then maybe just epoxy & light mat with a thicker coat of epoxy over that would be the way to go. Would give a nice hard surface to work on.

Regards the drawing, simple answer is the more you do the less it costs ... so if you can draw in the likes of Delft ship great , but i can work from basic plans on paper if needed.


Regards
Kim

[Arrow5]

As a frequent user of blue foam(hacksaw and sandpaper) I am amazed at that Orca in miniature. How is this cut so smoothly ?   This is the model boat world coming to where the model aircraft world has been for a few years.  BTW Kim how many people have asked for that sample ?