How would you construct a one-off submarine?

[roedj]

To All,

How would you construct a one-off submarine in the 4 to 5 feet (1.25m to 1.75m) size range? There would be absolutely no idea of molds nor mass production of any sort. I've built one-off surface craft before, mainly sail boats, and I have experience with the WEST system.

But how would you do it - cost be damned - within reason?

Perspiring minds want to know,

Dan (I've girded my loins so fire away)

[Kazzer]

Loins girded? Yuk! What a horrible thought!


Why bother with all that? There are plenty of existing boats in that size range. Plenty of challenges - if that's what you're after!

OTW MBD etc etc

[He Who Shall Not Be Named]

... shunting that imagery aside as best we can ...

Lost foam process, Dan.

David

[Scott T]

Girded my loins.. Put on his battle gear.

[roedj]

Mike,

Because no one offers a model of the boat I have in mind. The boat I have in mind will have to remain a tiny secret for now - sorry for that.

David,

I anticipated you would say "lost foam" and, of course, you're probably right given your extensive background in model making. But I don't have that background but I do have some limited experience with the bulkhead + stringer method and then epoxy glass with the WEST system over the entire thing inside and out. The bulkheads would stay in but would be mostly hollow to allow the addition of R/C equipment. The hull would be a dry hull, at least partially, and I realize it would probably be heavier than a simple fiberglass hull.

Or should I just go the "lost foam" method anyway? If I do go this way, i don't see how to create the detail in foam that I may be able to in wood. I also know I could probably learn anything given the proper coaching and threats.

Please advise,

Dan

[He Who Shall Not Be Named]

Plank-on-frame is so 50's!

Lost foam. Skin it with gell-coat then scribe and build-up the details. Dunk in gasoline. Done.

David

[roedj]

Plank-on-frame is so 50's!

Lost foam. Skin it with gell-coat then scribe and build-up the details. Dunk in gasoline. Done.

David

OK, please forgive my total ignorance here but you make it sound so easy and for you I'm sure it is. I've been net surfing on the "lost foam" method and it's not quite described as your method. Here's what I "think" I know - I know you'll correct me i*** I'm wrong.

1) Construct model shape in foam. The model I have in mind is WWII vintage so no circle of revolution shape. I take it from your reply that, at this stage, I do not have to include every little external detail. I use the ordinary blue/pink foam from HD/Lowes. I carve it with hot wire cutters, sharp knives, chisels, foam rasps, whatever works. I have no lathe.

When I'm satisfied with the overall general shape, I:

2) Cover it with one or two layers of light weight glass using the epoxy resin from the WEST system just to give it some strength.

Then:

3) Add external details. Using wood or metal or more foam add any external detail that is desired. Here's where I get lost. Do I then add more glass/epoxy to fix those external details in place? Do I finish up with a coat of gelcoat?

When that's done, I;

4) Dissolve the foam. Using acetone or MEK or gasoline (yuck) I dissolve the foam. I can only guess what I am supposed to do with that gooey mess.

Then:

5) Add more glass/epoxy or even carbon fiber inside the hull if more stiffness is required.

That's what I think I "know". How close am I?

Loins remain girded.

Torpedos los!

Dan

[He Who Shall Not Be Named]

You got it Dan.

Lay out the foam as though you were building a solid wood model using sections (layer-cake), buttock lofts, or waterline lofts; cut and file to shape; skin; add detail; skin. Dissolve foam. Cookies and milk.

Other than the substrate material the technique is the same as building a solid wooden model. No need to skin the inside -- the shell is alread a GRP structure. Duh!

Talking parts done, pal. Get to work!

David

[Scott T]

Here is a location at Subcommittee of someone building with foam.
It is a Perry sub made by Pirate. I hope he is not on the no-no list.
Paste the link into your browser to see if you can view it.

http://www.subcommittee.com/phpBB3/viewtopic.php?f=35&t=10370&p=68052&hilit=foam#p68052

[He Who Shall Not Be Named]

Here is a location at Subcommittee of someone building with foam.
It is a Perry sub made by Pirate. I hope he is not on the no-no list.
Paste the link into your browser to see if you can view it.

http://www.subcommittee.com/phpBB3/v...it=foam#p68052

Good stuff!

[Subculture]

The lost foam method is basically no different to carving out a hull from (very) soft balsa. If you have a plan for this secret squirrel boat ( what a luxury) then it may include hull lines, which you can loft off and create a foam hull using bread and butter methods of construction (do they use that term in the States).

Personally I would use the building method you feel most comfortable with. I use wood quite a bit, and prefer working with it to synthetics, because it smells nice when you work with it. It's also very cheap for me to use, as I tend to acquire wood from skips, offcuts from trees etc. Having said that I used foam for the yellow sub hull, because it was fast to work what is a very organic shape. I always prefer to make a master, reverse tool and then cast from that, it's more work than lost foam, but the end result is high quality, and it gives you option of producing more hulls either for friends or as spares if your existing boat gets clobbered.

The method of plank-on-frame is used by a UK modeller called David Jacques. He builds traditionally then glasses both sides. It's a quick(ish) method of construction, the main snag is that the hull will be quite thick, which means high displacement above the waterline, unless you use alternative construction for parts above the waterline. Even a dry hull will usually have some freeflood areas.

You could of course build a master using plank-on-frame then use that to pull a tool from. 1950's construction- nowt wrong with that. Most of my favourite stuff came from the 50's, and the model magazines were a lot better- they showed you how to make stuff.

The thing with any new technique is to build something small and inconsequential first to practice the technique. Mould making is NOT difficult. Building the master is the most difficult bit, the rest is pretty straightforward- time consuming, but straightforward.

[SSBN659]

Dan, Take a look at this thread from 2010. I used foam for my build and although it was only a display model, I could have used lost foam method and had a boat for the pond. hope it gives you some ideas.

http://forum.sub-driver.com/showthread.php?880-Modeling-the-last-of-the-forty-one-for-freedom&highlight=ROGERS