Has anyone ever tried using foam board to build a hull?

[GrandpaPhil]

I just got an idea from a buddy of mine who builds RC planes.

 

A lot people build RC planes out of foam board.

 

Has anyone here ever tried to build a POB hull out of foam board, maybe for a card build?

 

It would be sturdy and light.

 

It wouldn’t crush in one direction like corrugated cardboard does.

 

It also would be easy to work and join well to the hull “planking”.

Edited November 21, 2021 by GrandpaPhil

[wefalck]

Certainly. There is currently a project going on here: http://www.shipmodels.info/mws_forum/viewtopic.php?f=13&t=314249

 

Back in the 1960s at least the German model supplier Graupner offered styrofoam hulls and they offered a special primer (no water-based acrylics yet) that would not eat into it. They were discontinued after a few years in favour of vacuum-formed hulls made from ABS. Event with paint on, they would have dented relatively easily. My very first model had such hull.

 

Some 35 years ago I devised a POB construction for an iron tug by which I cut the bulkheads from 0.25 mm thick brass sheet, the keel from 0.5 mm brass sheet and filled the spaces with a special hard foam, which is essentially foamed-up Plexiglas. Very good material to work with, but difficult to get - at that time I had easy access, as my father worked for one of the daughter companies of the Plexiglas-manufacturers. The hull then was plated with copper-foil to imitate the rivetted iron plating. The reason for choosing these somewhat unorthodox materials was, that I wanted to make the bulwark-stanchions of this flush-decked tug in one piece with the bulkheads and at scale-thickness.

 

For my next project I will probably use a similar technique, but use 1 mm Plexiglass for the bulkheads and the keel-piece. The spaces will then be filled with this acrylic foam to prevent the thin styrene planking from sagging. The reasons is again, that this going to be a flush-decked sailing ship and I would like to make make the bulwark-stanchions in one piece with the bulkheads for easy definition of the hull shape.

[GrandpaPhil]

I might try it.

Edited November 21, 2021 by GrandpaPhil

[druxey]

Only if there are no curves: FoamCore board is rigid. If you mean dense styrofoam, it is very carveable and can be shaped to anything that you imagine. Just don't use hot wire to cut it: the off-gassing is very toxic!

[lmagna]

I have used "foam" board in a number of builds over the years.

 

I have built frames and keel out of both wood and plastic, (Different ships, not mixed) and filled in the spaces with sliced sections of foam like the build wefalck linked. When I used plastic I used a form of expanded PVC called "Sintra". It is in essence a light semi rigid PVC designed for and used by artist's. I find it much easier to use than standard polystyrene.  https://www.amazon.com/sintra-board/s?k=sintra+board

 

I have also used thinner layers of foam and cut and glued them in layers in the traditional bread and butter technique. This method works quite well with a number of ship hull designs and can be much easier and less messy than the fill between bulkhead or frame method.

 

The last method I have used is the solid hull method and I personally consider it the hardest and messiest of the bunch. Just like using wood, this is comprised of using the thicker versions of rigid foam and cutting away everything that does not look like the ship you are trying to build. It can be done freelance if the hull design is easy or simple like a "Springer" tug or barge. More complex hulls would benefit from the use of templates just as any other solid hull model would. The biggest benefit of this type of construction is that the finished product makes an excellent male form for making fiberglass molds.

 

If you have a place to work with it and don't mind the mess and extra finishing required to finish the carved surfaces, or are going to plank over it then ridged foam is a great media. It requires very few tools to form and none of them need to be specialized.

[Joe100]

The issue with foam board is that it’s not stable. You can ask the model railroad guys and they’ll tell you that it definitely has a shelf life. It off-gasses slowly and can cause all kinds of odd reactions years and years after the model is finished. 

[wefalck]

It depends on the material used for the foam. There are, for instance, acrylic foams (essentially foamed-up Plexiglas) that are longer stable than styrofoam. The reason is that they do not contain plasticers. 

 

On the other hand, a German kit company sold for a while hulls made from styrene foam extruded into a mould. I got one when I was around 6 or 7, built a crude model from it (my first 'semi'-scratch project) and eventually discarded it in my late 20s I think, when I cleared out some storage space in my parents' garage - if I remember correctly, it did not show appreciable signs of degradation, also because it had not been exposed to daylight really (being painted).

 

I would consider the foam not as a structural element per se, but rather something that helps you building up the hull around some structural members. That then you would cover in some sort of skin, that would remain stable, even if the foam degraded.

Edited January 19, 2022 by wefalck